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She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity
Goodreads Choice Award
Nominee for Readers' Favorite Science & Technology (2018)Carl Zimmer presents a history of our understanding of heredity in this sweeping, resonating overview of a force that shaped human society--a force set to shape our future even more radically.
She Has Her Mother's Laugh presents a profoundly original perspective on what we pass along from generation to generation. Charles Darwin played a crucial part in turning heredity into a scientific question, and yet he failed spectacularly to answer it. The birth of genetics in the early 1900s seemed to do precisely that. Gradually, people translated their old notions about heredity into a language of genes. As the technology for studying genes became cheaper, millions of people ordered genetic tests to link themselves to missing parents, to distant ancestors, to ethnic identities. . . .
But, Zimmer writes, "Each of us carries an amalgam of fragments of DNA, stitched together from some of our many ancestors. Each piece has its own ancestry, traveling a different path back through human history. A particular fragment may sometimes be cause for worry, but most of our DNA influences who we are--our appearance, our height, our penchants--in inconceivably subtle ways." Heredity isn't just about genes that pass from parent to child. Heredity continues within our own bodies, as a single cell gives rise to trillions of cells that make up our bodies. We say we inherit genes from our ancestors--using a word that once referred to kingdoms and estates--but we inherit other things that matter as much or more to our lives, from microbes to technologies we use to make life more comfortable. We need a new definition of what heredity is and, through Carl Zimmer's lucid exposition and storytelling, this resounding tour de force delivers it.
Weaving historical and current scientific research, his own experience with his two daughters, and the kind of original reporting expected of one of the world's best science journalists, Zimmer ultimately unpacks urgent bioethical quandaries arising from new biomedical technologies, but also long-standing presumptions about who we really are and what we can pass on to future generations.
She Has Her Mother's Laugh presents a profoundly original perspective on what we pass along from generation to generation. Charles Darwin played a crucial part in turning heredity into a scientific question, and yet he failed spectacularly to answer it. The birth of genetics in the early 1900s seemed to do precisely that. Gradually, people translated their old notions about heredity into a language of genes. As the technology for studying genes became cheaper, millions of people ordered genetic tests to link themselves to missing parents, to distant ancestors, to ethnic identities. . . .
But, Zimmer writes, "Each of us carries an amalgam of fragments of DNA, stitched together from some of our many ancestors. Each piece has its own ancestry, traveling a different path back through human history. A particular fragment may sometimes be cause for worry, but most of our DNA influences who we are--our appearance, our height, our penchants--in inconceivably subtle ways." Heredity isn't just about genes that pass from parent to child. Heredity continues within our own bodies, as a single cell gives rise to trillions of cells that make up our bodies. We say we inherit genes from our ancestors--using a word that once referred to kingdoms and estates--but we inherit other things that matter as much or more to our lives, from microbes to technologies we use to make life more comfortable. We need a new definition of what heredity is and, through Carl Zimmer's lucid exposition and storytelling, this resounding tour de force delivers it.
Weaving historical and current scientific research, his own experience with his two daughters, and the kind of original reporting expected of one of the world's best science journalists, Zimmer ultimately unpacks urgent bioethical quandaries arising from new biomedical technologies, but also long-standing presumptions about who we really are and what we can pass on to future generations.
657 pages, Hardcover
First published May 29, 2018
About the author
Carl Zimmer
50 books1,609 followersCarl Zimmer is a columnist for the New York Times and the author of 13 books about science. His latest book, She Has Her Mother's Laugh, will be published in May 2018. Zimmer is a frequent guest on Radiolab and has written hundreds of articles for magazines such as National Geographic, The Atlantic, and Wired. He is, to his knowledge, the only writer after whom a species of tapeworm has been named. Visit him at carlzimmer.com, on Facebook at facebook.com/carlzimmerauthor and on Twitter @carlzimmer.
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Displaying 1 - 30 of 966 reviews
June 21, 2020
The whole concept of heredity and race itself is a constructed, strange, and dangerous thing in the humanities, but the biological part of it is as fascinating as barely understood.
That´s a difficult and very detailed one, but it´s worth each gram of brain sweat, because it not only describes many topics around heredity, genes, epigenetic, and the fascinating development of those fields, but it also gives interesting implications for the future and under those some pretty realistic scenarios.
What can be done will be done and already now many expensive therapies are a thing for the rich and so will it be with the first options to pimp your baby, egg, and sperm. Of course, this will make all possible dystopian gene enhancing nightmares come true, because everyone wants the best for her/his kids and if the cash is there, it would be very bad parenting to not make the little bundles of joy smarter, healthier, longer living, happier, and more successful. The rich, beautiful, intelligent, friendly, strong,... kid vs the normal one. It´s already now pretty unfair with just wealthy vs. normal or even poor.
The most amazing is how smooth and logical the dry facts are combined with deep insights and the descriptions that will come true, depending on the laws of a country and its mentality towards new technologies, what could lead to an emancipated utopia or a stronger alienation between different social groups.
We are just at the very beginning and the epic fail of the human genome project and the arrogance around the underestimation of the RNA both showed that scientists tended to a bit too techno-optimistic mentality, quite kind of, "we just have to write down, not even crack, the code and bingo." So fine, yes, we have all those genomes and now we have barely any idea of how DNA and RNA interact in real, observable experiments and believe we could modify, tune and overclock the reproduction machinery with better tuning parts. Come on, that can´t end well, it´s like changing some parts of a huge industrial complex or a longly evolved computer with seemingly better parts without even knowing all of the functions of the removed parts and how the whole system works.
It amazed me that gene expression is so heavily depending on outer influences one wouldn´t think can have something to do with it and that even our bodies aren´t constructed quite kind of genetically symmetrical and exactly, but instead in a way that different body parts like two hands can have different genetic codes. So all the not understood mechanisms, the influence of any substance around and consumed by us, if and how the mind influences the body, if epigenetic or genetic will win the race, and how all that changes when genetic engineering modifies tiny aspects of extremely complex molecular machinery might make the day of the Überbabies come far later than expected.
But they will come crawling, driveling and already speaking whole, perfect sentences while they are parallel forming theories about quantum foam that bubbles like the drool on their sweet cheeks. Cultural conditioning epigenetics at its best, as they will still wear pink and play with Amazon warrior barbies before growing up and crashing their enemies perfectly styled, if they are Übergirls.
A wiki walk can be as refreshing to the mind as a walk through nature in this completely overrated real life outside books:
https://en.wikipedia.org/wiki/Epigene...
https://en.wikipedia.org/wiki/Heredity
https://en.wikipedia.org/wiki/Nature_...
That´s a difficult and very detailed one, but it´s worth each gram of brain sweat, because it not only describes many topics around heredity, genes, epigenetic, and the fascinating development of those fields, but it also gives interesting implications for the future and under those some pretty realistic scenarios.
What can be done will be done and already now many expensive therapies are a thing for the rich and so will it be with the first options to pimp your baby, egg, and sperm. Of course, this will make all possible dystopian gene enhancing nightmares come true, because everyone wants the best for her/his kids and if the cash is there, it would be very bad parenting to not make the little bundles of joy smarter, healthier, longer living, happier, and more successful. The rich, beautiful, intelligent, friendly, strong,... kid vs the normal one. It´s already now pretty unfair with just wealthy vs. normal or even poor.
The most amazing is how smooth and logical the dry facts are combined with deep insights and the descriptions that will come true, depending on the laws of a country and its mentality towards new technologies, what could lead to an emancipated utopia or a stronger alienation between different social groups.
We are just at the very beginning and the epic fail of the human genome project and the arrogance around the underestimation of the RNA both showed that scientists tended to a bit too techno-optimistic mentality, quite kind of, "we just have to write down, not even crack, the code and bingo." So fine, yes, we have all those genomes and now we have barely any idea of how DNA and RNA interact in real, observable experiments and believe we could modify, tune and overclock the reproduction machinery with better tuning parts. Come on, that can´t end well, it´s like changing some parts of a huge industrial complex or a longly evolved computer with seemingly better parts without even knowing all of the functions of the removed parts and how the whole system works.
It amazed me that gene expression is so heavily depending on outer influences one wouldn´t think can have something to do with it and that even our bodies aren´t constructed quite kind of genetically symmetrical and exactly, but instead in a way that different body parts like two hands can have different genetic codes. So all the not understood mechanisms, the influence of any substance around and consumed by us, if and how the mind influences the body, if epigenetic or genetic will win the race, and how all that changes when genetic engineering modifies tiny aspects of extremely complex molecular machinery might make the day of the Überbabies come far later than expected.
But they will come crawling, driveling and already speaking whole, perfect sentences while they are parallel forming theories about quantum foam that bubbles like the drool on their sweet cheeks. Cultural conditioning epigenetics at its best, as they will still wear pink and play with Amazon warrior barbies before growing up and crashing their enemies perfectly styled, if they are Übergirls.
A wiki walk can be as refreshing to the mind as a walk through nature in this completely overrated real life outside books:
https://en.wikipedia.org/wiki/Epigene...
https://en.wikipedia.org/wiki/Heredity
https://en.wikipedia.org/wiki/Nature_...
February 12, 2019
I learned a lot about the history of genetics, starting from single-celled creatures emerging from the primordial ooze, through the entire science of it beyond present day knowledge, into a conjectured future.
Together with genetics the author writes about cultural heredity without which we all be reinventing the wheel, just as certain apes have to learn in every generation how to use a stone to crack a nut and never develop further.
Zimmer also discusses race, which is a social construct he says originated in Spain in the time of Isabella and Ferdinand who believed that the corruption in the Catholic church was caused by Jews! And therefore Jews had either to convert to Catholicism or be put to death (shades of ISIS among other fundamentalists). People were at pains to prove that they had no Jews in their ancestral lines and so the concept of race was born. "Up until the Middle Ages, writers never used the word race in the sense that it would later take on—referring to a sharply defined biological group of people whose members were bound together by heredity."
The author who is European, together with colleagues from Asia and Africa had his genes tested.
All three of us have 1.4 million single-nucleotide polymorphisms in common. There were another 530,000 that I shared only with the Chinese person but not with the Nigerian. And there were 440,000 single-nucleotide polymorphisms that I shared with the Nigerian alone. All told, 83 percent of my variants were present in at least one of their genomes.
We were three people of African, Asian, and European descent, from three corners of the world. Three races, some might say. And yet we shared far more than what set us apart.
The science is heavy. I was constantly rereading and using the glossary. I learned about epigenetics which is when the dna code is not changed, but events change the genes for the next generation. The best known example of this is children born with foetal alcohol syndrome.
The author discusses the possible modification of babies by the wealthy who even now can have eggs fertilized in vitro and only the embryos free from inherited disorders, or of the 'right' gender, implanted and allowed to develop into babies. It is known what genes contribute to height, eye colour and even intelligence. But will governments decide to allow people to design their babies? Is it ethical?
Zimmer thinks that modification will creep in by the back door. Gene therapy to stop, say, osteoporosis in the elderly would be welcomed by all. So who could object if parents who could afford it gave it to their babies so they would never have to worry about it? Would this mean some adults who didn't get the therapy as babies and did develop osteoporosis could sue their parents for not having given it to them?
What about increasing intelligence by 10 points? Achievement is more strongly linked to parents income level - what they can afford to spend on education and enriching their children's lives, not to mention who they know to get into colleges and jobs. But there is obviously a component of intelligence there (not that you would always think it given some of the people who run things). What if these wealthy people with all the advantages of cultural heredity also increased their children's intelligence? Where would that leave the poor and already disadvantaged in our capitalist societies?
This is a wonderful book. If you like heavy books that require concentration, rereading, looking things up, it is for you. It expanded my world view, both back in time and forwards to a future I can't imagine any more than the children of the 60s could envisage life in the computer age, but like them at the dawning of electronics, so do I at the dawning of gene manipulation, see that the possibilies are endless.
I love the book and author so much my next book was Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures and since that was so good (5 star though, not 10 like this one), I'm going on to A Planet of Viruses
Together with genetics the author writes about cultural heredity without which we all be reinventing the wheel, just as certain apes have to learn in every generation how to use a stone to crack a nut and never develop further.
Zimmer also discusses race, which is a social construct he says originated in Spain in the time of Isabella and Ferdinand who believed that the corruption in the Catholic church was caused by Jews! And therefore Jews had either to convert to Catholicism or be put to death (shades of ISIS among other fundamentalists). People were at pains to prove that they had no Jews in their ancestral lines and so the concept of race was born. "Up until the Middle Ages, writers never used the word race in the sense that it would later take on—referring to a sharply defined biological group of people whose members were bound together by heredity."
The author who is European, together with colleagues from Asia and Africa had his genes tested.
All three of us have 1.4 million single-nucleotide polymorphisms in common. There were another 530,000 that I shared only with the Chinese person but not with the Nigerian. And there were 440,000 single-nucleotide polymorphisms that I shared with the Nigerian alone. All told, 83 percent of my variants were present in at least one of their genomes.
We were three people of African, Asian, and European descent, from three corners of the world. Three races, some might say. And yet we shared far more than what set us apart.
The science is heavy. I was constantly rereading and using the glossary. I learned about epigenetics which is when the dna code is not changed, but events change the genes for the next generation. The best known example of this is children born with foetal alcohol syndrome.
The author discusses the possible modification of babies by the wealthy who even now can have eggs fertilized in vitro and only the embryos free from inherited disorders, or of the 'right' gender, implanted and allowed to develop into babies. It is known what genes contribute to height, eye colour and even intelligence. But will governments decide to allow people to design their babies? Is it ethical?
Zimmer thinks that modification will creep in by the back door. Gene therapy to stop, say, osteoporosis in the elderly would be welcomed by all. So who could object if parents who could afford it gave it to their babies so they would never have to worry about it? Would this mean some adults who didn't get the therapy as babies and did develop osteoporosis could sue their parents for not having given it to them?
What about increasing intelligence by 10 points? Achievement is more strongly linked to parents income level - what they can afford to spend on education and enriching their children's lives, not to mention who they know to get into colleges and jobs. But there is obviously a component of intelligence there (not that you would always think it given some of the people who run things). What if these wealthy people with all the advantages of cultural heredity also increased their children's intelligence? Where would that leave the poor and already disadvantaged in our capitalist societies?
This is a wonderful book. If you like heavy books that require concentration, rereading, looking things up, it is for you. It expanded my world view, both back in time and forwards to a future I can't imagine any more than the children of the 60s could envisage life in the computer age, but like them at the dawning of electronics, so do I at the dawning of gene manipulation, see that the possibilies are endless.
I love the book and author so much my next book was Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures and since that was so good (5 star though, not 10 like this one), I'm going on to A Planet of Viruses
June 18, 2018
Yes, it's long – about 540 or so actual pages of text, followed by a glossary, bibliography and endnotes – but She Has Her Mother's Laugh does not waste a single page. Carl Zimmer has produced a masterpiece of science writing, distilling incredibly complex concepts into understandable and relatable language by using narrative journalism and personal anecdotes to perfect effect. Any questions you've had about DNA, genes, inheritance, and the moral and ethical questions surrounding them will be answered – as will numerous other questions you didn't realize you had.
Zimmer leaves no topic unexplored, from history to the future, from eugenics to in vitro fertilization, from cancer to evolution. It's all there, and it's all tremendous. I found exactly zero weaknesses in this book, and highly recommend it to anyone wanting to expand their knowledge about how they got here and where we all are going.
Zimmer leaves no topic unexplored, from history to the future, from eugenics to in vitro fertilization, from cancer to evolution. It's all there, and it's all tremendous. I found exactly zero weaknesses in this book, and highly recommend it to anyone wanting to expand their knowledge about how they got here and where we all are going.
June 5, 2019
As I was reading this I couldn't help but wish that science books would have been as interesting as this one, back in my school days. Or maybe I've gotten smarter? Either way this is a very good and thorough look at what makes us who we are. An exploration of genetics from Burbank who was famous for his gardens, and crossmatched his veggies. His potatoes, are the only potatoes McDonalds will use their french fries, to now. Mendels peas, and the horrifying use of eugenics.
We have come a long way, understanding now how traits, diseases, and appearance are all passed on in our DNA. This book traces the steps that were taken, as well as the missteps, to the point where now we are looking at the genome for a possible cure for various diseases. I watched a show on CRISPR, which is in this books closing chapters.
Well written, nicely divided by chapter, this is an intriguing look at our past, our present and our possible future.
We have come a long way, understanding now how traits, diseases, and appearance are all passed on in our DNA. This book traces the steps that were taken, as well as the missteps, to the point where now we are looking at the genome for a possible cure for various diseases. I watched a show on CRISPR, which is in this books closing chapters.
Well written, nicely divided by chapter, this is an intriguing look at our past, our present and our possible future.
November 11, 2023
A small slice of information pertinent to the actual content of this book has been bracketed for those concerned. Though I suspect the majority of you are not here for that.
Has it ever occurred to you that the quantum interference patterns within the microtubules of your brain are culpable for the tragic passing of Norm MacDonald, you bastard!? Wait, permit me a mulligan, if you will. Have you ever, while producing cavitation bubbles in the geometry of space-time like unto a certain carnivorous marine crustacean of the order Stomatopoda (i.e. Mantis Shrimp) utilizing the carbon fiber planing hull of a Colombian drug boat, the Archimedes Principle, and gratuitous combustion, turned to regard your bound captives with a white residue clinging to your whiskers like titanium dioxide and said the following?
“More quantum mechanics mechanisms were also introduced. Exocytosis, as an intriguing discovery, was chosen as the indispensable and pivotal step. In the standby phase of the synaptic bouton, exocytosis was seen as a staged quantal event based on the quantum tunneling effect, resulting in momentarily increasing the probability of exocytosis (actually, it was named the selection of events in quantum mechanics). This selection mechanism augmented the likelihood for exocytosis and led to amplified excitatory postsynaptic potentials. Then, a coherent coupling of boutons in a dendron occurred. Because the dendrons in the cerebral cortex contain countless synaptic connections, there is an enormous amount of quantum transmission in the human brain, which inevitably leads to the randomness and freedom of mental phenomena-free will.”
Did one of your hostages then rebuff you thusly?
“After more than twenty years, no subsequent development of this ancestral hypothesis has occurred; additionally, the true identity of psychons was never discovered, despite countless works focused on cortical architecture.”
And, after running Monte Carlo sims in your wetware until your decision tree has been whittled into a javelin by the hideous parsimony of a certain razor (i.e. a sharp instrument for partitioning blow for manageable ingestion confiscated from a certain English Franciscan friar (i.e. William of Ockham)), hurled the sharp stick of your conviction down fate’s gaping hallway to strike the only remaining target in resolution-space whilst screaming the immortal words of Bill Hicks, “Ahhh, ha ha ha, it's gone, it's gone, it's gone. Oh, it's gone. All the shitty shows are gone, all the idiots screaming in the fucking wind are dead, I love it. Leaving nothing but a cool, beautiful serenity called... Arizona Bay. That's right, when L.A. falls in the fucking ocean and is flushed away, all that it will leave...is Arizona Bay.” Abruptly banking so hard you flip the boat an impossible number of times, accelerating laterally like alien technology, skipping across the water like a green basilisk lizard until it’s spinning so fast it resembles nothing so much as a blurry oblong shape, gaining FPS as if a bug in the simulation has inextricably linked some part of the physics engine to the refresh rate of the observer. Ascending skyward as if in a Bethesda game and continuing to rotate before exploding into impossibly long polygonal spikes which, due to shoddy collision detection, (i.e. the collection of algorithms that react to the interaction of two adjacent overlapping geometries), clip through the known universe and collapse this instance of reality?
Do you wish to learn about the particulars of genetics? (A pun so crass that Gregor Mendel would throw his head back as if billions and billions (i.e. Carl Sagan) of Nutted But She Still Sucking memes suddenly cried out in ecstasy and were suddenly silenced.) Then eliminate, with extreme prejudice, those who would multiply entities without necessity (i.e. telling your boy William “go fuck thyself” ) by bifurcating your flow diagram. Have you ever, while in a mad rush to procure a book recommended to you by an unhinged country bumpkin, kicked a man so violently in the bollocks that he saw, in a magnificent flash of pyrotechnic pain, life in all its ribald generative glory, and gurgled out what follows?
“Young lady, you and I, and everyone - the world over, are bound by a common inheritance, stretching back in an unbroken chain of procreative successes. In these most improbable unions, a twisted ladder of phosphates and sugars, zipped and unzipped in just such a way, interacting with the environment epigenetically, expressing and suppressing according to transcription factors and..
Flattening his gonads with the instep of your foot like warm pizza dough.
“METHYLATION PATTERNS!” He whistles through clenched teeth like a balloon unpinched. Falling to his knees and guarding his germ line from further deformation with shaking hands. “Winnowing the genetic population through predation, disease, starvation... Preserving only what...”
Cuffing him about the ears you say: “I have known many gods. He who denies them is as blind as he who trusts them too deeply. I seek not beyond death. It may be the blackness averred by the Nemedian skeptics, or Crom's realm of ice and cloud, or the snowy plains and vaulted halls of the Nordheimer's Valhalla. I know not, nor do I care. Let me live deep while I live; let me know the rich juices of red meat and stinging wine on my palate, the hot embrace of white arms, the mad exultation of battle when the blue blades flame and crimson, and I am content. Let teachers and philosophers brood over questions of reality and illusion. I know this: if life is illusion, then I am no less an illusion, and being thus, the illusion is real to me. I live, I burn with life, I love, I slay, and am content.”
Capitulating to this senseless barbarism he rolls into a gutter and finishes with a quote: “Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”
Well, I’ll be frank, you were way out of line here, and that enthusiastic ornithologist was just out searching for information on the mating habits of Blue Footed Boobies. And that, my good friend, should give you a bit of the dicky tummy.
[This book is a history of heredity and a tool to help you better understand the current science of genetics. Charting the exciting breakthroughs which have deepened our understanding without shying away from its numerous, tragic misuses.]
If our species is to move forward, it must solve what has been called The Twin Nuclei Problem of Cell and Atom. We must navigate a landscape fundamentally changed by our mastery over atomic energy and our increasing fluency in the language of biological manipulation. Those genies are out of the bottle, and…
Abruptly capsizes vessel.
Has it ever occurred to you that the quantum interference patterns within the microtubules of your brain are culpable for the tragic passing of Norm MacDonald, you bastard!? Wait, permit me a mulligan, if you will. Have you ever, while producing cavitation bubbles in the geometry of space-time like unto a certain carnivorous marine crustacean of the order Stomatopoda (i.e. Mantis Shrimp) utilizing the carbon fiber planing hull of a Colombian drug boat, the Archimedes Principle, and gratuitous combustion, turned to regard your bound captives with a white residue clinging to your whiskers like titanium dioxide and said the following?
“More quantum mechanics mechanisms were also introduced. Exocytosis, as an intriguing discovery, was chosen as the indispensable and pivotal step. In the standby phase of the synaptic bouton, exocytosis was seen as a staged quantal event based on the quantum tunneling effect, resulting in momentarily increasing the probability of exocytosis (actually, it was named the selection of events in quantum mechanics). This selection mechanism augmented the likelihood for exocytosis and led to amplified excitatory postsynaptic potentials. Then, a coherent coupling of boutons in a dendron occurred. Because the dendrons in the cerebral cortex contain countless synaptic connections, there is an enormous amount of quantum transmission in the human brain, which inevitably leads to the randomness and freedom of mental phenomena-free will.”
Did one of your hostages then rebuff you thusly?
“After more than twenty years, no subsequent development of this ancestral hypothesis has occurred; additionally, the true identity of psychons was never discovered, despite countless works focused on cortical architecture.”
And, after running Monte Carlo sims in your wetware until your decision tree has been whittled into a javelin by the hideous parsimony of a certain razor (i.e. a sharp instrument for partitioning blow for manageable ingestion confiscated from a certain English Franciscan friar (i.e. William of Ockham)), hurled the sharp stick of your conviction down fate’s gaping hallway to strike the only remaining target in resolution-space whilst screaming the immortal words of Bill Hicks, “Ahhh, ha ha ha, it's gone, it's gone, it's gone. Oh, it's gone. All the shitty shows are gone, all the idiots screaming in the fucking wind are dead, I love it. Leaving nothing but a cool, beautiful serenity called... Arizona Bay. That's right, when L.A. falls in the fucking ocean and is flushed away, all that it will leave...is Arizona Bay.” Abruptly banking so hard you flip the boat an impossible number of times, accelerating laterally like alien technology, skipping across the water like a green basilisk lizard until it’s spinning so fast it resembles nothing so much as a blurry oblong shape, gaining FPS as if a bug in the simulation has inextricably linked some part of the physics engine to the refresh rate of the observer. Ascending skyward as if in a Bethesda game and continuing to rotate before exploding into impossibly long polygonal spikes which, due to shoddy collision detection, (i.e. the collection of algorithms that react to the interaction of two adjacent overlapping geometries), clip through the known universe and collapse this instance of reality?
Do you wish to learn about the particulars of genetics? (A pun so crass that Gregor Mendel would throw his head back as if billions and billions (i.e. Carl Sagan) of Nutted But She Still Sucking memes suddenly cried out in ecstasy and were suddenly silenced.) Then eliminate, with extreme prejudice, those who would multiply entities without necessity (i.e. telling your boy William “go fuck thyself” ) by bifurcating your flow diagram. Have you ever, while in a mad rush to procure a book recommended to you by an unhinged country bumpkin, kicked a man so violently in the bollocks that he saw, in a magnificent flash of pyrotechnic pain, life in all its ribald generative glory, and gurgled out what follows?
“Young lady, you and I, and everyone - the world over, are bound by a common inheritance, stretching back in an unbroken chain of procreative successes. In these most improbable unions, a twisted ladder of phosphates and sugars, zipped and unzipped in just such a way, interacting with the environment epigenetically, expressing and suppressing according to transcription factors and..
Flattening his gonads with the instep of your foot like warm pizza dough.
“METHYLATION PATTERNS!” He whistles through clenched teeth like a balloon unpinched. Falling to his knees and guarding his germ line from further deformation with shaking hands. “Winnowing the genetic population through predation, disease, starvation... Preserving only what...”
Cuffing him about the ears you say: “I have known many gods. He who denies them is as blind as he who trusts them too deeply. I seek not beyond death. It may be the blackness averred by the Nemedian skeptics, or Crom's realm of ice and cloud, or the snowy plains and vaulted halls of the Nordheimer's Valhalla. I know not, nor do I care. Let me live deep while I live; let me know the rich juices of red meat and stinging wine on my palate, the hot embrace of white arms, the mad exultation of battle when the blue blades flame and crimson, and I am content. Let teachers and philosophers brood over questions of reality and illusion. I know this: if life is illusion, then I am no less an illusion, and being thus, the illusion is real to me. I live, I burn with life, I love, I slay, and am content.”
Capitulating to this senseless barbarism he rolls into a gutter and finishes with a quote: “Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”
Well, I’ll be frank, you were way out of line here, and that enthusiastic ornithologist was just out searching for information on the mating habits of Blue Footed Boobies. And that, my good friend, should give you a bit of the dicky tummy.
[This book is a history of heredity and a tool to help you better understand the current science of genetics. Charting the exciting breakthroughs which have deepened our understanding without shying away from its numerous, tragic misuses.]
If our species is to move forward, it must solve what has been called The Twin Nuclei Problem of Cell and Atom. We must navigate a landscape fundamentally changed by our mastery over atomic energy and our increasing fluency in the language of biological manipulation. Those genies are out of the bottle, and…
Abruptly capsizes vessel.
June 28, 2019
I started this with a healthy dose of trepidation. I said to someone the other day that I didn’t really believe in genes and I think she did one of those double-takes – you know, oh no, he’s one of ‘those’ men, one who decides not to believe in something everyone otherwise knows is true, like climate change or vaccines or irony, and has some mind-numbing boring reason why what obviously does exist, doesn’t. But really my problem with genes goes back to my reading Not In Our Genes years ago – and then more recently books like Fatal Invention or Biology as Ideology. It’s not that I don’t believe in genes – it is more that I don’t believe in what genes are often said to be able to do. I’ve also read far too many books about Eugenics, particularly the impact of the Eugenics movement on education – and so part of me thought, as I started this book, that it was likely to be a kind of call to arms about all the benefits of genes. A kind of updated version of The Blank Slate, say. However, this is much better than I was expecting.
You get a bit of a history of inheritance in this book which then merges into a history of genetics. He provides a nice and easy to understand explanation for why we can’t really clean out our gene pool (even if after Hitler we actually still wanted to do such a thing) and shows that diversity is perhaps the most beautiful thing about the world, even if it is something humans seems to not only distrust, but to even go out of our way to limit, and not just in our own species.
Any book that deals with genes needs to deal with the horrors of eugenics – not merely the Nazis or Henry Ford and so on – but also the sterilisation programs that went on and on and on even after WW2 and the other horrors stacked upon horrors that much of the 20th century was built upon. It would be nice to think that such horrors might present us with something of a warning, but we humans don’t really respond all that well to warnings – as George Herbert would say, ‘call in thy death’s-head there, tie up thy fears’.
Much of this is covered in the first part of the book – but I actually felt that the book improved after this part. I thought part 3 was a particular highlight – we like to think that we have ‘a’ genetic code, that you write out that particular alphabet and you get you. But it seems infinitely more complicated than this. For instance, there are even errors in copying our genetic code across our own bodies, where our hands, given they are so far apart from each other, might provide slightly different genetic markers from one another due to mis-copyings along the way. The differences are slight, obviously, and the genetic code on one hand would be more similar to that on the other than either would be to, say, my brothers’ DNA, but the fact that there might be differences at all had never occurred to me.
The dance of environment and genes was also something I’d never really thought about as much as I ought to have. The fact some genes only basically turn on in certain environments complicates the story much more than I think most of us assume.
Part of me has always thought that making people must be a bit easier than it looks – you know, since it so rarely goes wrong. I mean, if I was given the instructions to make a human from two cells, I could pretty well guarantee I would stuff it up nine-times-out-of-ten – maybe even more often than that. But nature (for want of a better metaphor) rarely stuffs up. Even so, the more he explained, the more I had to resist the temptation to think the whole thing is impossible – you know, despite all evidence to the contrary – and complex life forms, such as us, simply shouldn’t exist. There is one part in this book where he talks about Irish giants, people from Ireland whose ‘just keep growing’ gene never quite turned off and so they ended growing to 9 foot tall. A lot of this book feels like someone is pulling your leg, you know.
I think we need to be more terrified of genetics than we are too, particularly genetic manipulation. His chapter at the start of part five on Phoebus and Phaethon – and how easy it is to think you know the consequences of what you are about to do when you really don’t – pretty much sums up my fears about just about everything in that part of the book. There is so much potential for things to go horribly wrong.
This book gives a nice introduction to what genetics is good for, and what it isn’t. As someone quoted in this says at one point, before you start killing people to make the world a better place, perhaps we should tackle inequality and see how much that addresses the differences we observe. It would be nice if more people thought like that.
You get a bit of a history of inheritance in this book which then merges into a history of genetics. He provides a nice and easy to understand explanation for why we can’t really clean out our gene pool (even if after Hitler we actually still wanted to do such a thing) and shows that diversity is perhaps the most beautiful thing about the world, even if it is something humans seems to not only distrust, but to even go out of our way to limit, and not just in our own species.
Any book that deals with genes needs to deal with the horrors of eugenics – not merely the Nazis or Henry Ford and so on – but also the sterilisation programs that went on and on and on even after WW2 and the other horrors stacked upon horrors that much of the 20th century was built upon. It would be nice to think that such horrors might present us with something of a warning, but we humans don’t really respond all that well to warnings – as George Herbert would say, ‘call in thy death’s-head there, tie up thy fears’.
Much of this is covered in the first part of the book – but I actually felt that the book improved after this part. I thought part 3 was a particular highlight – we like to think that we have ‘a’ genetic code, that you write out that particular alphabet and you get you. But it seems infinitely more complicated than this. For instance, there are even errors in copying our genetic code across our own bodies, where our hands, given they are so far apart from each other, might provide slightly different genetic markers from one another due to mis-copyings along the way. The differences are slight, obviously, and the genetic code on one hand would be more similar to that on the other than either would be to, say, my brothers’ DNA, but the fact that there might be differences at all had never occurred to me.
The dance of environment and genes was also something I’d never really thought about as much as I ought to have. The fact some genes only basically turn on in certain environments complicates the story much more than I think most of us assume.
Part of me has always thought that making people must be a bit easier than it looks – you know, since it so rarely goes wrong. I mean, if I was given the instructions to make a human from two cells, I could pretty well guarantee I would stuff it up nine-times-out-of-ten – maybe even more often than that. But nature (for want of a better metaphor) rarely stuffs up. Even so, the more he explained, the more I had to resist the temptation to think the whole thing is impossible – you know, despite all evidence to the contrary – and complex life forms, such as us, simply shouldn’t exist. There is one part in this book where he talks about Irish giants, people from Ireland whose ‘just keep growing’ gene never quite turned off and so they ended growing to 9 foot tall. A lot of this book feels like someone is pulling your leg, you know.
I think we need to be more terrified of genetics than we are too, particularly genetic manipulation. His chapter at the start of part five on Phoebus and Phaethon – and how easy it is to think you know the consequences of what you are about to do when you really don’t – pretty much sums up my fears about just about everything in that part of the book. There is so much potential for things to go horribly wrong.
This book gives a nice introduction to what genetics is good for, and what it isn’t. As someone quoted in this says at one point, before you start killing people to make the world a better place, perhaps we should tackle inequality and see how much that addresses the differences we observe. It would be nice if more people thought like that.
July 19, 2018
A truly mammoth book that should have been edited down to a few hundred pages. The interesting tidbits and stories were immersed in unnecessary prose and benign chapters that served no purpose except to increase the word count. Some stories SHINED and AMAZED (especially the chapter on Chimera, which was utterly fascinating), but it’s a shame the reader has to wade through all of the weeds to discover the gems.
April 29, 2021
I see this book, She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity by Carl Zimmer, as a continuation of Siddhartha Mukherjee’s The Gene: An Intimate History. I wrote in my review of Mukherjee’s book:
"My ability to follow the book, from start to finish without any serious problems, is amazing! The author is clear, and he captivates a reader’s interest all the way through."
The very same is true of Zimmer’s book! I highly recommend it. I think everyone attempting to keep afloat in the new discoveries of genealogy should read it.
The book recaps both the history and the newest of the science. It starts with the ideas of Aristotle, covers of course Mendel and eugenics, then continues up to contemporary times with discussion of transgenerational epigenetic inheritance, mitochondrial replacement therapy, CRISPR, mosaicism and genetic chimeras and much more.
Concerning the nature versus nurture debate the author makes clear the complexity of separating the two.
To understand where we are today, one must study the steps taken to where we stand now. The book looks at diverse topics through individual in-depth stories. The reader is given details about both the scientific experiments done and about the people who did them.
Please look at the list of related books I have mentioned at the bottom of my review. This indicates the width of the book’s coverage. All of these topics are interrelated and it is through the in-depth stories that readers interest remains glued.
I do think the book could have been been tightened a bit. Topics are discussed and then returned to later. The titles of chapters and parts give little indication of what they will contain; the titles are too diffuse. You understand what the title signifies only after it is read. Often chapters end with a question rather than a summary. This leads one forward to the what follows next, but for those seeking to learn, a summary of each chapter would have been more helpful.
Joe Ochman narrates the audiobook. He reads quickly. For those attempting to learn, his rapid speed makes this more difficult. When the topic concerns scientific terms, I had trouble. It is less difficult when the topic is biographical or on a general theme. I could follow it for the most part, but I prefer a slower narration. It was OK, so I have given the narration two stars. I could always hear Ochman’s words. It was my head that needed more time to think. In these sections I had to rewind.
I want everyone to read this book. There is tons here that is fascinating! The telling via stories keeps you interested. Scientific terms are clearly but succinctly explained. The book gives a great summary of where we stand today in the field of genealogy and heredity.
***************
Related reading:
*The Gene: An Intimate History 4 stars by Siddhartha Mukherjee
*Before the Dawn: Recovering the Lost History of Our Ancestors 4 stars by Nicholas J. Wade
*Beyond Words: What Animals Think and Feel 4 stars by Carl Safina
*I Contain Multitudes: The Microbes Within Us and a Grander View of Life 3 stars Ed Yong
*The Beak of the Finch: A Story of Evolution in Our Time 2 stars by Jonathan Weiner
*The Tangled Tree: A Radical New History of Life TBR by David Quammen
*The Guarded Gate: Bigotry, Eugenics and the Law That Kept Two Generations of Jews, Italians, and Other European Immigrants Out of America TBR by Daniel Okrent
*The Child Who Never Grew TBR by Pearl S. Buck
"My ability to follow the book, from start to finish without any serious problems, is amazing! The author is clear, and he captivates a reader’s interest all the way through."
The very same is true of Zimmer’s book! I highly recommend it. I think everyone attempting to keep afloat in the new discoveries of genealogy should read it.
The book recaps both the history and the newest of the science. It starts with the ideas of Aristotle, covers of course Mendel and eugenics, then continues up to contemporary times with discussion of transgenerational epigenetic inheritance, mitochondrial replacement therapy, CRISPR, mosaicism and genetic chimeras and much more.
Concerning the nature versus nurture debate the author makes clear the complexity of separating the two.
To understand where we are today, one must study the steps taken to where we stand now. The book looks at diverse topics through individual in-depth stories. The reader is given details about both the scientific experiments done and about the people who did them.
Please look at the list of related books I have mentioned at the bottom of my review. This indicates the width of the book’s coverage. All of these topics are interrelated and it is through the in-depth stories that readers interest remains glued.
I do think the book could have been been tightened a bit. Topics are discussed and then returned to later. The titles of chapters and parts give little indication of what they will contain; the titles are too diffuse. You understand what the title signifies only after it is read. Often chapters end with a question rather than a summary. This leads one forward to the what follows next, but for those seeking to learn, a summary of each chapter would have been more helpful.
Joe Ochman narrates the audiobook. He reads quickly. For those attempting to learn, his rapid speed makes this more difficult. When the topic concerns scientific terms, I had trouble. It is less difficult when the topic is biographical or on a general theme. I could follow it for the most part, but I prefer a slower narration. It was OK, so I have given the narration two stars. I could always hear Ochman’s words. It was my head that needed more time to think. In these sections I had to rewind.
I want everyone to read this book. There is tons here that is fascinating! The telling via stories keeps you interested. Scientific terms are clearly but succinctly explained. The book gives a great summary of where we stand today in the field of genealogy and heredity.
***************
Related reading:
*The Gene: An Intimate History 4 stars by Siddhartha Mukherjee
*Before the Dawn: Recovering the Lost History of Our Ancestors 4 stars by Nicholas J. Wade
*Beyond Words: What Animals Think and Feel 4 stars by Carl Safina
*I Contain Multitudes: The Microbes Within Us and a Grander View of Life 3 stars Ed Yong
*The Beak of the Finch: A Story of Evolution in Our Time 2 stars by Jonathan Weiner
*The Tangled Tree: A Radical New History of Life TBR by David Quammen
*The Guarded Gate: Bigotry, Eugenics and the Law That Kept Two Generations of Jews, Italians, and Other European Immigrants Out of America TBR by Daniel Okrent
*The Child Who Never Grew TBR by Pearl S. Buck
January 2, 2019
Zimmer provides an accessible compilation of the history and current scientific research regarding heredity. Fortunately, he uses individual examples to help illustrate and explain the basic theories. Yea! There are a lot of fascinating facts to absorb!
First of all, paleogenetics has used the DNA extracted from ancient skeletons to reveal that we are all ‘mutts’, and that racial purity is a myth. Further, our genome is comprised of DNA in our chromosomes, PLUS the genes in our cells’ mitochondria (inherited solely from the mother). Our DNA is an amalgamation of DNA from ancient humanoids—including Neanderthals which provided larger brain size. In addition, roughly 8% of our genome originated in viruses.
Mothers and their unborn babies trade DNA back and forth through the placenta, and EACH retains that DNA for years. AND, if the mother has additional babies, some of the firstborn’s DNA can get passed onto the next child, and so on. This makes one wonder about the impact of DNA transfer in surrogate mothers, doesn’t it?
Speaking of siblings—the manner in which DNA replicates is through meiosis which results in siblings getting vastly different assortments of DNA from each parent. Researchers have found that a pair of siblings might share as much as 62% of their DNA or as little as 37%.
Then there is this whole concept of chimeras. Opposite sex twins can exchange stem cells, or even fuse as embryos. The result is confusion—some cells in the resulting child may be XX and some may be XY. There is even a case where a chimera mother was accused of not being her children’s biological mother because of DNA discrepancies.
Now we have the gene-editing technique known as CRISPER that has challenged the ethics of gene engineering. This may have some place in gene therapy for those with rare diseases, but probably not with something like height. There are so many DNA bits that are associated with determining height, that the resulting combinations number over 2 million.
And lastly, there is the bizarre way in which some genes can be turned on/off by environmental factors. This adaptation can then be passed on to their progeny while that factor exists. Environmental stresses such as heat, salt, toxins, or infection can trigger these epigenetic responses.
Highly recommend.
First of all, paleogenetics has used the DNA extracted from ancient skeletons to reveal that we are all ‘mutts’, and that racial purity is a myth. Further, our genome is comprised of DNA in our chromosomes, PLUS the genes in our cells’ mitochondria (inherited solely from the mother). Our DNA is an amalgamation of DNA from ancient humanoids—including Neanderthals which provided larger brain size. In addition, roughly 8% of our genome originated in viruses.
Mothers and their unborn babies trade DNA back and forth through the placenta, and EACH retains that DNA for years. AND, if the mother has additional babies, some of the firstborn’s DNA can get passed onto the next child, and so on. This makes one wonder about the impact of DNA transfer in surrogate mothers, doesn’t it?
Speaking of siblings—the manner in which DNA replicates is through meiosis which results in siblings getting vastly different assortments of DNA from each parent. Researchers have found that a pair of siblings might share as much as 62% of their DNA or as little as 37%.
Then there is this whole concept of chimeras. Opposite sex twins can exchange stem cells, or even fuse as embryos. The result is confusion—some cells in the resulting child may be XX and some may be XY. There is even a case where a chimera mother was accused of not being her children’s biological mother because of DNA discrepancies.
Now we have the gene-editing technique known as CRISPER that has challenged the ethics of gene engineering. This may have some place in gene therapy for those with rare diseases, but probably not with something like height. There are so many DNA bits that are associated with determining height, that the resulting combinations number over 2 million.
And lastly, there is the bizarre way in which some genes can be turned on/off by environmental factors. This adaptation can then be passed on to their progeny while that factor exists. Environmental stresses such as heat, salt, toxins, or infection can trigger these epigenetic responses.
Highly recommend.
March 20, 2020
Zimmer gives us an accessible and engaging presentation on genetics and heredity with the implications for health, intelligence, personality and our future. He explores the science around DNA, RNA, and the epigenome. The discussions are substantive, but not dense. For those with limited exposure to the material, this is an excellent introduction. For those who are well read in these topics, there may be little new, except perhaps from some of the many side stories that are interspersed with the science.
Zimmer starts off with history. He highlights the Habsburgs who married first cousins for generations resulting in the Habsburg jaw and recurring ailments from inbreeding. Zimmer illustrates science with many personal stories. Another is that of the author Pearl Buck and her daughter, Carrie, who suffered from the serious genetic disease phenylketonuria (PKU) before its cause was understood. I enjoyed the story of Luther Burbank, a prolific plant breeder. He was a legend in his own time, who was inspired by Darwin’s book The Variation of Animals and Plants under Domestication. Zimmer focuses on eugenics, a tragic misuse of science. The story of Henry Goddard and Emma Wolverton is particularly interesting.
In 1897 Emma Wolverton was committed to The Vineland Training School, a home for the “feebleminded” in New Jersey. Henry Goddard learned about the Simon-Binet test visiting Europe. He decided to develop it to test the feebleminded at Vineland School. He invented the word “moron” to describe people like Emma who performed on the tests a few years below their chronological age. The next lower classification was imbecile then idiot. An underlying purpose to Goddard’s research was to identify people he felt should not be allowed to have children. The era of eugenics was just beginning. Eugenicists wanted to prevent the birth of “defectives”, regardless of race, by sterilization or other means. They were sure North European whites would have far fewer “defectives.” Eugenics was used to justify white Anglo-Saxon superiority.
Goddard hired people to investigate Emma’s family tree. In 1912 he published a book The Kallikak Family that documented generations of mentally ill, alcoholic and immoral people that his investigators found comprised Emma’s ancestors. The book was very influential and taken as proof by the eugenicists that “feeblemindedness” was inherited. Goddard’s influence extended to the testing of immigrants for admission to the U.S. and soldiers in the Army. Not surprisingly the vast majority of Jews, Italians and Russians trying to enter the country were found to be feebleminded on Goddard’s test. The test questions heavily favored educated U.S. residents. In the tests of those entering the Army nearly half of whites and ninety per cent of blacks scored as morons or below. The Kallikak Family was used as evidence in the famous 1927 Supreme Court decision to uphold Virginia’s plan to sterilize Carrie Buck, a young black woman. Goddard’s book was translated into German. Hitler read about it and reiterated its message soon after in Mein Kampf. The Nazis would sterilize and euthanize hundreds of thousands of people considered mentally defective. By the 1930s opposition in the U.S. by scientists to eugenics was strong and the public became disenchanted by the eugenicists' closeness to the Nazis. In 1939 the Kallikak book was no longer in print but its use in college texts persisted. In the 1980s genealogists examined the Kallikak (Emma Wolverton) family tree in the book and found it filled with erroneous relationships and omitted relationships that contradicted Goddard’s premise.
Zimmer moves on to current science, enlightening us about mosaicism and chimerism. Mosaicism refers to a single individual with cells containing different DNA due to mutation. Cancer is an obvious example. Zimmer outlines other examples such as David Merrick the elephant man whose bony growths were due to mosaicism. He also describes a person who had cells with both X and Y chromosomes while other cells had only a single X. Apparently in the early development of the embryo a dividing cell failed to pass along a Y chromosome. This mosaicism produced an individual with both male and female genitalia. Zimmer outlines many more cases of conditions and diseases due to mosaicism.
Zimmer presents examples of chimerism, which describes individuals who have cells with the genome of other individuals in addition to their own. A mother’s placenta is leaky. It allows cells from one individual to enter another. This can be an exchange between mother and child or between twins. Bizarre events also occur such as the baby born with some cells containing XX chromosomes and other cells having XY chromosomes. This child had both an ovary and a testicle. The apparent cause was the fertilization of two eggs by two different sperm from the father. The zygotes then merged to form one embryo. One sperm carried an X chromosome, the other a Y. Zimmer describes many more unique cases such as one where a mother was told her children couldn’t be hers based on a DNA test. Eventually, tests on other cells in her body showed her to be the mother.
Zimmer discusses the microbiome and broadens the concept of heredity. Most plants and animals are dependent on microbes. Zimmer gives many examples of the different ways microbes are inherited. In humans microbes come directly from the mother’s vaginal canal at birth and from the breasts when nursing. As children grow they build their microbiome from contact with family and friends. Each species has its own unique microbiome. Our closest relative, the chimpanzee, has a microbiome quite different from ours. These microbes perform important functions that keep us healthy or if impaired make us sick. Having “good” genes means those of your microbiome need to be good too.
Zimmer weighs in on transgenerational epigenetic inheritance, a controversial subject. Gene expression is regulated by an epigenetic process known as methylation, which can turn genes on or off, ramp them up or down. It goes on throughout are lives often in response to environmental factors. The question is whether epigenetic factors such as methylation in somatic cells can affect the germ cells and thus be inherited. When fertilization occurs the stripping of the epigenome begins and continues in the early embryo. The methyl groups are replaced by those necessary for the embryo’s development. At about three weeks, some of the embryo’s cells become germ cells. Their epigenome is again stripped and a new one consistent with their new identity applied. Could any of the parents’ epigenetic factors survive all this stripping and resetting of methyl groups?
Experiments with mice seem to show that the stress incurred by a parent can alter the behavior of future progeny. Zimmer describes several other experiments that seem to show that some epigenetic factors must be getting through. Naysayers say these experiments are too few and too small to be trusted. It’s an open question. Plants, however, don’t form their germ cells in early development. Plant germ cells come from adult somatic cells when the plant is ready to reproduce. These cells will have incurred many epigenetic factors from their environment and all these factors are not stripped from the new germ cells as they are in animals. Thus epigenetic inheritance is widespread in plants.
Another form of inheritance Zimmer explores is culture. Richard Dawkins coined the term for this inheritable factor, the meme, purposely named to rhyme with gene. The widespread passing on of learned skills is uniquely human. Humans, unlike other animals, are proficient teachers and their offspring are proficient learners who cooperate with each other to help each other learn. Zimmer describes experiments that show the stark differences between the way humans learn vs chimpanzees and monkeys. Thus humans are endowed with this cumulative knowledge that can also be considered something heritable.
Zimmer looks at CRISPR technology and pre-implementation genetic screening as ways to control heredity. CRISPR allows the precise replacement of genes. In somatic cells this is not controversial, but in germ cells this permanent alteration affecting all progeny raises concern. Certainly everyone wants to see genes that cause Huntington’s disease, cystic fibrosis and other diseases eliminated from the gene pool. But there is the danger of unforeseen consequences. And once the technology starts being used we will undoubtedly see parents opting for genetic changes to improve their children’s appearance, intelligence and athletic ability. The technology will be limited to those that can afford it and could lead to the creation of an elite class of humans. Perhaps more immediate is pre-implementation screening of germ cells for in vitro fertilization to select out germ cells that carry problematic genes or to select in those that carry an extra benefit. While this process doesn’t carry all the ethical concerns of CRISPR, these procedures are also too expensive for most people. Zimmer notes that 1.6% of children in the U.S. were conceived via in vitro fertilization in 2014 so screening for good genes seems a logical next step. Another possibility for those who can’t produce viable sperm or eggs is turning skin or other somatic cells into germ cells. This has been done with mice producing healthy offspring.
Use of CRISPR technology on plants and animals also opens up many new possibilities. Mosquitoes can be given genes that prevent them from spreading malaria or even genes to eliminate mosquitoes altogether. Who would miss them? We would only find out after the fact. Are we ready to begin grand experiments to reshape our environment? Our track record of tinkering with the environment isn’t very good. The ability of organisms to reshape their environment is well documented. Zimmer considers these new environments another form of heredity. Difficult choices face us. The world our children and theirs inherit will be poised on a precipice between existential dangers and powerful technologies to reshape that world and its inhabitants.
Zimmer starts off with history. He highlights the Habsburgs who married first cousins for generations resulting in the Habsburg jaw and recurring ailments from inbreeding. Zimmer illustrates science with many personal stories. Another is that of the author Pearl Buck and her daughter, Carrie, who suffered from the serious genetic disease phenylketonuria (PKU) before its cause was understood. I enjoyed the story of Luther Burbank, a prolific plant breeder. He was a legend in his own time, who was inspired by Darwin’s book The Variation of Animals and Plants under Domestication. Zimmer focuses on eugenics, a tragic misuse of science. The story of Henry Goddard and Emma Wolverton is particularly interesting.
In 1897 Emma Wolverton was committed to The Vineland Training School, a home for the “feebleminded” in New Jersey. Henry Goddard learned about the Simon-Binet test visiting Europe. He decided to develop it to test the feebleminded at Vineland School. He invented the word “moron” to describe people like Emma who performed on the tests a few years below their chronological age. The next lower classification was imbecile then idiot. An underlying purpose to Goddard’s research was to identify people he felt should not be allowed to have children. The era of eugenics was just beginning. Eugenicists wanted to prevent the birth of “defectives”, regardless of race, by sterilization or other means. They were sure North European whites would have far fewer “defectives.” Eugenics was used to justify white Anglo-Saxon superiority.
Goddard hired people to investigate Emma’s family tree. In 1912 he published a book The Kallikak Family that documented generations of mentally ill, alcoholic and immoral people that his investigators found comprised Emma’s ancestors. The book was very influential and taken as proof by the eugenicists that “feeblemindedness” was inherited. Goddard’s influence extended to the testing of immigrants for admission to the U.S. and soldiers in the Army. Not surprisingly the vast majority of Jews, Italians and Russians trying to enter the country were found to be feebleminded on Goddard’s test. The test questions heavily favored educated U.S. residents. In the tests of those entering the Army nearly half of whites and ninety per cent of blacks scored as morons or below. The Kallikak Family was used as evidence in the famous 1927 Supreme Court decision to uphold Virginia’s plan to sterilize Carrie Buck, a young black woman. Goddard’s book was translated into German. Hitler read about it and reiterated its message soon after in Mein Kampf. The Nazis would sterilize and euthanize hundreds of thousands of people considered mentally defective. By the 1930s opposition in the U.S. by scientists to eugenics was strong and the public became disenchanted by the eugenicists' closeness to the Nazis. In 1939 the Kallikak book was no longer in print but its use in college texts persisted. In the 1980s genealogists examined the Kallikak (Emma Wolverton) family tree in the book and found it filled with erroneous relationships and omitted relationships that contradicted Goddard’s premise.
Zimmer moves on to current science, enlightening us about mosaicism and chimerism. Mosaicism refers to a single individual with cells containing different DNA due to mutation. Cancer is an obvious example. Zimmer outlines other examples such as David Merrick the elephant man whose bony growths were due to mosaicism. He also describes a person who had cells with both X and Y chromosomes while other cells had only a single X. Apparently in the early development of the embryo a dividing cell failed to pass along a Y chromosome. This mosaicism produced an individual with both male and female genitalia. Zimmer outlines many more cases of conditions and diseases due to mosaicism.
Zimmer presents examples of chimerism, which describes individuals who have cells with the genome of other individuals in addition to their own. A mother’s placenta is leaky. It allows cells from one individual to enter another. This can be an exchange between mother and child or between twins. Bizarre events also occur such as the baby born with some cells containing XX chromosomes and other cells having XY chromosomes. This child had both an ovary and a testicle. The apparent cause was the fertilization of two eggs by two different sperm from the father. The zygotes then merged to form one embryo. One sperm carried an X chromosome, the other a Y. Zimmer describes many more unique cases such as one where a mother was told her children couldn’t be hers based on a DNA test. Eventually, tests on other cells in her body showed her to be the mother.
Zimmer discusses the microbiome and broadens the concept of heredity. Most plants and animals are dependent on microbes. Zimmer gives many examples of the different ways microbes are inherited. In humans microbes come directly from the mother’s vaginal canal at birth and from the breasts when nursing. As children grow they build their microbiome from contact with family and friends. Each species has its own unique microbiome. Our closest relative, the chimpanzee, has a microbiome quite different from ours. These microbes perform important functions that keep us healthy or if impaired make us sick. Having “good” genes means those of your microbiome need to be good too.
Zimmer weighs in on transgenerational epigenetic inheritance, a controversial subject. Gene expression is regulated by an epigenetic process known as methylation, which can turn genes on or off, ramp them up or down. It goes on throughout are lives often in response to environmental factors. The question is whether epigenetic factors such as methylation in somatic cells can affect the germ cells and thus be inherited. When fertilization occurs the stripping of the epigenome begins and continues in the early embryo. The methyl groups are replaced by those necessary for the embryo’s development. At about three weeks, some of the embryo’s cells become germ cells. Their epigenome is again stripped and a new one consistent with their new identity applied. Could any of the parents’ epigenetic factors survive all this stripping and resetting of methyl groups?
Experiments with mice seem to show that the stress incurred by a parent can alter the behavior of future progeny. Zimmer describes several other experiments that seem to show that some epigenetic factors must be getting through. Naysayers say these experiments are too few and too small to be trusted. It’s an open question. Plants, however, don’t form their germ cells in early development. Plant germ cells come from adult somatic cells when the plant is ready to reproduce. These cells will have incurred many epigenetic factors from their environment and all these factors are not stripped from the new germ cells as they are in animals. Thus epigenetic inheritance is widespread in plants.
Another form of inheritance Zimmer explores is culture. Richard Dawkins coined the term for this inheritable factor, the meme, purposely named to rhyme with gene. The widespread passing on of learned skills is uniquely human. Humans, unlike other animals, are proficient teachers and their offspring are proficient learners who cooperate with each other to help each other learn. Zimmer describes experiments that show the stark differences between the way humans learn vs chimpanzees and monkeys. Thus humans are endowed with this cumulative knowledge that can also be considered something heritable.
Zimmer looks at CRISPR technology and pre-implementation genetic screening as ways to control heredity. CRISPR allows the precise replacement of genes. In somatic cells this is not controversial, but in germ cells this permanent alteration affecting all progeny raises concern. Certainly everyone wants to see genes that cause Huntington’s disease, cystic fibrosis and other diseases eliminated from the gene pool. But there is the danger of unforeseen consequences. And once the technology starts being used we will undoubtedly see parents opting for genetic changes to improve their children’s appearance, intelligence and athletic ability. The technology will be limited to those that can afford it and could lead to the creation of an elite class of humans. Perhaps more immediate is pre-implementation screening of germ cells for in vitro fertilization to select out germ cells that carry problematic genes or to select in those that carry an extra benefit. While this process doesn’t carry all the ethical concerns of CRISPR, these procedures are also too expensive for most people. Zimmer notes that 1.6% of children in the U.S. were conceived via in vitro fertilization in 2014 so screening for good genes seems a logical next step. Another possibility for those who can’t produce viable sperm or eggs is turning skin or other somatic cells into germ cells. This has been done with mice producing healthy offspring.
Use of CRISPR technology on plants and animals also opens up many new possibilities. Mosquitoes can be given genes that prevent them from spreading malaria or even genes to eliminate mosquitoes altogether. Who would miss them? We would only find out after the fact. Are we ready to begin grand experiments to reshape our environment? Our track record of tinkering with the environment isn’t very good. The ability of organisms to reshape their environment is well documented. Zimmer considers these new environments another form of heredity. Difficult choices face us. The world our children and theirs inherit will be poised on a precipice between existential dangers and powerful technologies to reshape that world and its inhabitants.
September 24, 2020
"Heredity is not a cosmic imperative but a process that emerges from biological ingredients and is modified into new forms."
Carl Zimmer, an award-winning New York Times columnist and science writer, follows the study of heredity from the ancient Greeks to Darwin, Mendel, Burbank and including today's current understandings and still unknown mysteries. Who are our ancestors? What diseases may we be unknowingly passing on? What is our true ethnicity? Should culture and environment be considered in the science of heredity? What are the ethical implications of what is known today and what may be discovered tomorrow?
Zimmer does a splendid job of making even the most complex ideas understandable to the lay reader. I was completely awed by the brilliance of these dedicated geneticists. It may seem ludicrous to dedicate a lifetime of research to a cockroach or a sea clam until one realizes how that study contributes to the big picture and how it may influence future research and discoveries.
Rather than trying to cover all the science Zimmer includes in this lengthy tome, I chose a smattering of information that I found to be mind boggling. Who knew? The list could have been extremely long.
1. There are 800 genes that influence height. 2,000,000 variants accout for much of the variation in height.
2. Two skin conditions arise from the same mutation but take on different forms depending on when it appears during development.
3. Mothers carry fetal cells in their bloodstream which remain after the birth of the child or even after an abortion or miscarriage. These "foreign" cells may be why women are more prone to autoimmune diseases. This mixture of cells is called microchimerism and may also have benefits for the mother.
4. Non-genetic traits can develop and be passed on for generations and then, for no apparent reason, die out.
5. Anyone with any Western European heritage has some Neanderthal DNA.
6. The heritability of weight may not influence our cells to store fat but rather it is the presence of the bacteria christensenella in our gut.
7. There is not a single species of bacteria upon which our own life depends or that all humans share. "We house a personalized zoo."
8. Although microbiologists have been naming species of bacteria for well over a century, they have still only identified a tiny fraction.
9. A single zygotic cell has the potential to become any type of cell.
10. Epigenetics, the collection of molecules that envelop our genes and control what they do, may prove to be the link between nature and nurture.
11. In an effort to block diseases mitochondrial replacement therapy moved the nucleus of a fertilized egg into another egg which had been removed. This led to the term "the three parent child" and also to endless ethical questions.
This is definitely not a book you can read quickly. But the wealth of information on heredity, both past and present, is well worth the time: the progression of this science, the proven truths and the disproven notions, the scientists that used the science to advance knowledge and those who twisted facts to support their own findings or their biases is invaluable. This is who we are; maybe not one big happy family, but with world-wide similarities that are truly mystifying.
"It is entirely possible that before long, scientists will learn how to swab the inside of people's cheeks and transform their cells into sperm or eggs, ready for in vitro fertilization. This gives a whole new meaning to heredity. Your ancestor could be a skin cell."
Carl Zimmer, an award-winning New York Times columnist and science writer, follows the study of heredity from the ancient Greeks to Darwin, Mendel, Burbank and including today's current understandings and still unknown mysteries. Who are our ancestors? What diseases may we be unknowingly passing on? What is our true ethnicity? Should culture and environment be considered in the science of heredity? What are the ethical implications of what is known today and what may be discovered tomorrow?
Zimmer does a splendid job of making even the most complex ideas understandable to the lay reader. I was completely awed by the brilliance of these dedicated geneticists. It may seem ludicrous to dedicate a lifetime of research to a cockroach or a sea clam until one realizes how that study contributes to the big picture and how it may influence future research and discoveries.
Rather than trying to cover all the science Zimmer includes in this lengthy tome, I chose a smattering of information that I found to be mind boggling. Who knew? The list could have been extremely long.
1. There are 800 genes that influence height. 2,000,000 variants accout for much of the variation in height.
2. Two skin conditions arise from the same mutation but take on different forms depending on when it appears during development.
3. Mothers carry fetal cells in their bloodstream which remain after the birth of the child or even after an abortion or miscarriage. These "foreign" cells may be why women are more prone to autoimmune diseases. This mixture of cells is called microchimerism and may also have benefits for the mother.
4. Non-genetic traits can develop and be passed on for generations and then, for no apparent reason, die out.
5. Anyone with any Western European heritage has some Neanderthal DNA.
6. The heritability of weight may not influence our cells to store fat but rather it is the presence of the bacteria christensenella in our gut.
7. There is not a single species of bacteria upon which our own life depends or that all humans share. "We house a personalized zoo."
8. Although microbiologists have been naming species of bacteria for well over a century, they have still only identified a tiny fraction.
9. A single zygotic cell has the potential to become any type of cell.
10. Epigenetics, the collection of molecules that envelop our genes and control what they do, may prove to be the link between nature and nurture.
11. In an effort to block diseases mitochondrial replacement therapy moved the nucleus of a fertilized egg into another egg which had been removed. This led to the term "the three parent child" and also to endless ethical questions.
This is definitely not a book you can read quickly. But the wealth of information on heredity, both past and present, is well worth the time: the progression of this science, the proven truths and the disproven notions, the scientists that used the science to advance knowledge and those who twisted facts to support their own findings or their biases is invaluable. This is who we are; maybe not one big happy family, but with world-wide similarities that are truly mystifying.
"It is entirely possible that before long, scientists will learn how to swab the inside of people's cheeks and transform their cells into sperm or eggs, ready for in vitro fertilization. This gives a whole new meaning to heredity. Your ancestor could be a skin cell."
April 27, 2019
This is a wonderful book about heredity. It is such a comprehensive treatment of the subject. The hardcover version of the book is 672 pages long, about 575 pages of text followed by references and an index. So, this is not a book to be read in a couple of days. But don't let the length keep you from reading the book. It is terrific--filled with stories and anecdotes that are all quite engaging. This is a very engaging book!
It wasn't until the last couple of hundred years that it was generally understood that many human traits are heritable. This came to me as a surprise. Didn't people notice how families seem to have similar traits? Yes, but the mechanism of heredity was not really understood.
The story of Luther Burbank was very interesting. During the 1870's he developed a series of plant hybrids that were marvelous. He developed the Russet Burbank potato. He developed a grafting technique to deliver 20,000 plum trees in a single summer. He was not a scientist, but he had developed an instinct for understanding what might work in solving problems with plants. Burbank claimed to be religious, and that God will be gradually revealed by our savior, science.(!) The Mexican artist Frida Kahlo painted a portrait of Luther Burbank, shown here.
Charles Darwin came up with a hypothesis called "pangenesis", in his book The Variation of Animals and Plants under Domestication. It was very similar to the Lamarckian concept of acquired characteristics; body parts can be altered by the environment, and this alteration could pass down to descendants. Francis Galton tried to prove Darwin's hypothesis and failed, by transfusing blood among rabbits. Recent experiments, however, show some ability to transfer traits through blood transfusions. Darwin publicly chided Galton for not conducting successful experiments. But neither Darwin nor Galton really had a clue about the mechanism for inheritance.
Carl Zimmer goes into some detail about how the idea of eugenics came about. The Vineland School for the Feebleminded sent out researchers in the early 1900's, to families of the children who lived there. They found that feeblemindedness was inherited, just like Mendel's peas. The research director, Henry Goddard, became a eugenicist. He didn't want to kill the feebleminded, but he did want to prevent them from having children. He brought a team of fieldworkers to Ellis Island, to give intelligence tests to new immigrants. While trying to make the tests independent of culture, they nevertheless found that about 40% of the immigrants were feebleminded. He had tried to account for cultural differences and language barriers in his tests.
The book contains lots of discussion about race and skin color. But the book shows that race is not a meaningful biological concept. Even at the DNA level, there is no clear-cut way to distinguish races.
All sorts of interesting hereditary correlations are discussed in the book. Race and skin color, slave children and height, height among different countries, low intelligence and accidents, high intelligence and fast inspection times, high intelligence and life expectancy. Environmental influences are also described; iodine in the diet can increase intelligence to a point, and good diets can increase height.
In fact, one cannot treat genes and the environment independently. Each one influences the other. In one study of heritability of intelligence, it was bound that heritability is about 60% among affluent families, but close to 0% among poorer families--at least in the United States. This seems not to hold in Europe. Also, heritability increases as we age, perhaps a sort of feedback loop. It was found in the 1970's that intelligence can be changed. This was the reason that the Head Start program was started. It raised the graduation rate of children, by as much as 10% in the case of children whose mothers didn't finish high school.
There are some fascinating chapters about chimeras; fraternal twins who can share each others' blood types, or other genes from each other. Also, it is interesting how fetal cells can remain in a woman's body for years or even decades. They can sense what type of organ they reside in, and transform themselves into that type of cell. This can be helpful or harmful, depending on the situation.
The book tells an incredible story about how researchers trained bees to pull on a string to obtain food. Without training, none of the bees figured out the puzzle, but by incremental-step training, many of them learned to trick. They returned the trained bees to their hive, and after a while, untrained bees were brought to the experiment. Many of them now knew how to procure the food; 2nd, 3rd, and even 4th-hand communications.
There is so much more in the book, all told with marvelous stories. There are fascinating discussions of memes as a form of cultural heredity, and the revolution that has started with CRISPR technology. Don't be put off by the length of the book. The author's ability to tell a story makes this a very enjoyable read.
It wasn't until the last couple of hundred years that it was generally understood that many human traits are heritable. This came to me as a surprise. Didn't people notice how families seem to have similar traits? Yes, but the mechanism of heredity was not really understood.
The story of Luther Burbank was very interesting. During the 1870's he developed a series of plant hybrids that were marvelous. He developed the Russet Burbank potato. He developed a grafting technique to deliver 20,000 plum trees in a single summer. He was not a scientist, but he had developed an instinct for understanding what might work in solving problems with plants. Burbank claimed to be religious, and that God will be gradually revealed by our savior, science.(!) The Mexican artist Frida Kahlo painted a portrait of Luther Burbank, shown here.
Charles Darwin came up with a hypothesis called "pangenesis", in his book The Variation of Animals and Plants under Domestication. It was very similar to the Lamarckian concept of acquired characteristics; body parts can be altered by the environment, and this alteration could pass down to descendants. Francis Galton tried to prove Darwin's hypothesis and failed, by transfusing blood among rabbits. Recent experiments, however, show some ability to transfer traits through blood transfusions. Darwin publicly chided Galton for not conducting successful experiments. But neither Darwin nor Galton really had a clue about the mechanism for inheritance.
Carl Zimmer goes into some detail about how the idea of eugenics came about. The Vineland School for the Feebleminded sent out researchers in the early 1900's, to families of the children who lived there. They found that feeblemindedness was inherited, just like Mendel's peas. The research director, Henry Goddard, became a eugenicist. He didn't want to kill the feebleminded, but he did want to prevent them from having children. He brought a team of fieldworkers to Ellis Island, to give intelligence tests to new immigrants. While trying to make the tests independent of culture, they nevertheless found that about 40% of the immigrants were feebleminded. He had tried to account for cultural differences and language barriers in his tests.
The book contains lots of discussion about race and skin color. But the book shows that race is not a meaningful biological concept. Even at the DNA level, there is no clear-cut way to distinguish races.
All sorts of interesting hereditary correlations are discussed in the book. Race and skin color, slave children and height, height among different countries, low intelligence and accidents, high intelligence and fast inspection times, high intelligence and life expectancy. Environmental influences are also described; iodine in the diet can increase intelligence to a point, and good diets can increase height.
In fact, one cannot treat genes and the environment independently. Each one influences the other. In one study of heritability of intelligence, it was bound that heritability is about 60% among affluent families, but close to 0% among poorer families--at least in the United States. This seems not to hold in Europe. Also, heritability increases as we age, perhaps a sort of feedback loop. It was found in the 1970's that intelligence can be changed. This was the reason that the Head Start program was started. It raised the graduation rate of children, by as much as 10% in the case of children whose mothers didn't finish high school.
There are some fascinating chapters about chimeras; fraternal twins who can share each others' blood types, or other genes from each other. Also, it is interesting how fetal cells can remain in a woman's body for years or even decades. They can sense what type of organ they reside in, and transform themselves into that type of cell. This can be helpful or harmful, depending on the situation.
The book tells an incredible story about how researchers trained bees to pull on a string to obtain food. Without training, none of the bees figured out the puzzle, but by incremental-step training, many of them learned to trick. They returned the trained bees to their hive, and after a while, untrained bees were brought to the experiment. Many of them now knew how to procure the food; 2nd, 3rd, and even 4th-hand communications.
There is so much more in the book, all told with marvelous stories. There are fascinating discussions of memes as a form of cultural heredity, and the revolution that has started with CRISPR technology. Don't be put off by the length of the book. The author's ability to tell a story makes this a very enjoyable read.
September 17, 2018
Se tem um autor que sempre vou fazer questão de ler o que lançar é o Carl Zimmer. Foi de longe uma das maiores motivações para eu começar a blogar e escrever sobre ciência. E é um dos jornalistas com o conhecimento de biologia mais amplo que leio, que sabe integrar áreas da biologia como muitos pesquisadores envolvidos nas descobertas que descreve não sabem.
Este livro não éexcessão exceção. Nos últimos 10-15 anos, o sequenciamento genético ficou muito mais barato e acessível. Com isso, a quantidade de genes e genomas sequenciados cresceu assombrosamente. Muito mais do que nossa capacidade de interpretar, analisar e guardar estes dados cresceu, inclusive. E o Carl Zimmer reconta uma parte de como isso aconteceu e das descobertas que vieram com essa capacidade.
Em temas com grande potencial para interpretações complicadas e carregadas historicamente, como o caso da genética humana e da eugenia, os exemplos que se escolhe para tratar de um assunto falam muito sobre onde o autor quer chegar. E Zimmer escolheu ótimos casos e exemplos para tratar dos avanços recentes em genômica. Discussões sobre a hereditariedade de características como inteligência e comportamento, de como estabelecemos esse tipo de relação, de "pureza de sangue", de doenças genéticas e outros temas delicados são feitos com excelentes exemplos e muito cuidado. Terminando com uma discussão bem informada sobre CRISPr, que não sobe no hype e fala do que precisamos desenvolver e os reais potenciais.
Recomendo para qualquer um que quiser entender um pouco de genética pelas mãos de uma das pessoas mais habilidosas para contar isso.
Este livro não é
Em temas com grande potencial para interpretações complicadas e carregadas historicamente, como o caso da genética humana e da eugenia, os exemplos que se escolhe para tratar de um assunto falam muito sobre onde o autor quer chegar. E Zimmer escolheu ótimos casos e exemplos para tratar dos avanços recentes em genômica. Discussões sobre a hereditariedade de características como inteligência e comportamento, de como estabelecemos esse tipo de relação, de "pureza de sangue", de doenças genéticas e outros temas delicados são feitos com excelentes exemplos e muito cuidado. Terminando com uma discussão bem informada sobre CRISPr, que não sobe no hype e fala do que precisamos desenvolver e os reais potenciais.
Recomendo para qualquer um que quiser entender um pouco de genética pelas mãos de uma das pessoas mais habilidosas para contar isso.
March 26, 2022
A truly excellent work of nonfiction: informative to the point of being downright mind-bending, and also highly readable and engaging. This is a large book, about heredity in all its permutations, and the history of our understanding of it: from selective breeding to CRISPR, from cultural legacies to microbiomes to eugenics. The biggest focus is genetics, but as it turns out that’s a whole lot more complicated than most of us realize, when we often carry disparate lineages of cells even within our own bodies!
Below, some wild and fascinating things I learned from this book:
- You get 50% of your genes from each parent, but within the parents’ egg and sperm cells, meiosis scrambles up the DNA they received from each of their parents—meaning, your mom doesn’t necessarily give you exactly half of what she received from each of her parents. Thus, you might be more genetically similar to some grandparents than others. Siblings on average share 50% of their DNA, but in reality, siblings have been found with ranges from 37-62%.
- For the same reason, the further someone is from you on your family tree, the less likely you are to share any DNA at all (at least, anything recognizably individual; 99%+ of the human genome, after all, is shared by all humans). Among third cousins, 1% share no individual DNA. Among fourth cousins, it’s 25%.
- And the same holds true with ancestors: the further back you go, the greater the chance that no recognizable individual segments of DNA come from any particular ancestor. Go back 10 generations (roughly 250-300 years) and there’s a 46% chance you are not “related” to any given ancestor at all.
- We think of our ancestry as a forking tree, with no overlap. The problem is, go back one or two thousand years, and the number of individual forks representing your ancestors adds up to more people than have ever lived. Mathematically, all of our ancestors had to be related to each other.
- Mathematical models have also shown that, within a population (say, people of European descent), if you go back 1000 years, anyone who has any descendants living today is an ancestor of all people in that population living today. And that five thousand years ago, anyone with any living descendants is an ancestor of all living people. [I was disappointed that the author didn’t question this, because it’s obviously untrue. Native American and Pacific Islander populations left the Old World more than 5000 years ago, and have only been in contact for the last 200-500 years. Even if all Native Americans and Pacific Islanders alive today have since acquired Old World ancestry—which another study in the book assumes not to be the case, and the author also doesn’t question that one—I think it’s certainly fair to say that in the last few centuries, every European, African and Asian person has not acquired both Native American and Polynesian ancestry.]
- The oldest modern human fossils in Europe, from about 45,000 years ago, show no genetic indication of any relation to modern Europeans, whose DNA is an amalgamation of several later groups of migrants. These oldest Europeans, genetically, appear to have come from another continent entirely and vanished 37,000 years ago.
- Meanwhile, modern humans bear traces of Neanderthal DNA: about 0.08-0.34% for Africans, and 1-1.4% for non-Africans. Other ancient Neanderthal relatives, Denisovans, are also still around in our DNA, with some Pacific populations having up to 5% from this group, while East Asians and Native Americans carry noticeable amounts of Denisovan DNA as well. (So, oddly, does the book’s European-descended author!)
- A weird factoid from twin studies: twins are often misclassified as fraternal vs. identical. In one study in the Netherlands, 19% of parents gave the wrong answer. Misclassified identical twins, however, are just as similar to each other as correctly classified identical twins.
- Once a person is conceived, cells continue to divide—and there’s a possibility for mutation at any point in that process. (Happily, we set aside our egg and sperm cells early, so these mutations generally don’t make it to our children.) Thus, a person can be a “mosaic,” having different cells in the body coming from different lineages—which can cause diseases, or patchwork skin pigmentation, or make no difference at all. In fact, everyone has some mutations in their cell DNA. Mosaicism can also cure diseases, as the cells with a working version of a gene take over from the bad ones.
- Even freakier: by the time we’re born, our cells may not be entirely our own. Twins sharing a womb swap cells back and forth, as was first discovered in a blood donor who had two blood types. As it turned out, some of her blood also had Y chromosomes. Turns out, she’d had a twin who died soon after birth, but his blood lived on in her.
- Mothers and babies also exchange cells, despite the mechanisms that are supposed to prevent this. One study of girls found that 13% had at least some Y chromosomes in their blood, presumably from their brothers (or fetuses that never made it), maintained in the mother’s body and then passed on to their daughters.
- And those stem cells that get into the mother’s body? They can stay forever. One theory is that these “foreign” cells may contribute to higher rates of autoimmune disease among women. But in an incredible twist, because these are stem cells, they can also pick up new roles in her body—even healing it. In one truly wild case, a woman with hepatitis had an entire lobe of her liver regrown with Y chromosome-bearing cells, whose paternity was traced to her boyfriend. Turns out, she’d had an abortion years before—but the male fetus’s stem cells stuck around and made themselves useful. Meanwhile, one study, involving autopsies of elderly women, found Y chromosome cells in the brains of 63% of them.
- Then there are the “chimeras” resulting from twins merging in the early stages of embryonic development. When the twins are male and female, an intersex child can result, but with same-sex twins it tends to go unnoticed. One American woman almost lost custody of her four children when DNA tests showed that she wasn’t their mother—as it turned out, genetically, her reproductive system belonged to a different person (her unborn sister!) from the rest of her body. As far as most of her body was concerned, she was her children’s aunt despite having conceived and given birth to them. [The book does not address why Child Protective Services would have removed her children to foster care over this, but hooray American officialdom.] One has to wonder: how many men have gotten similarly negative results on paternity tests, but without the reassurance of knowing the kids came out of their body, assumed betrayal rather than hunting down the truth?
- Then, of course, by the numbers only half of the cells in our body are even human—the rest are microbes along for the ride. (Human cells are far bigger than microbes, though, so by weight we’re much more human than that!) We pick up our microbiome all over the place as small children: not just from our parents (though we start picking it up in the birth canal and from our mothers’ milk, and many strains of bacteria are highly heritable), but also from other people we’re around and whatever we put in our mouths. The human microbiome is wildly diverse: one study of the microbes in people’s navels found dozens in each person, and not a single microbe common to all.
- Meanwhile, the mitochondria in the cells of all living things appears to have originally been a microbe itself, whose symbiotic relationship with other cells led to becoming a part of them. This is why mitochondria has its own DNA (in humans, passed on only from the mother).
- Cancer can be contagious: a facial tumor killing Tasmanian devils is traceable to a single devil, and the animals spread it by biting each other’s faces in fights. Likewise, a genital tumor in dogs is traceable back thousands of years. Only a couple of cases of contagious cancer have been reported in humans; preventing this may be one reason why our bodies react so negatively to transplants from other people.
- CRISPR gene editing carries the possibility to transform populations, but it’s not as simple as you might think. Many mutations naturally die out, but a “gene drive” (a gene programmed to destroy competing versions, which can also occur in the wild) can prevent that. Scientists are experimenting with programming mosquitoes to not pass on malaria—but cautiously, knowing the ecological catastrophes that have resulted from releasing new organisms into an environment in the past.
- We also shouldn’t think that CRISPR for humans, should it become available for germline editing, would immediately transform the gene pool, even if the edited genes happen to be passed on to the recipients’ descendants (a big “if” for all the reasons seen above). For instance, pre-implantation genetic diagnosis of human embryos is available now for those undergoing in vitro fertilization, and generally used to avoid passing on hereditary diseases. However, with Huntington’s disease (which any parent would want to prevent), from 2002-2012, only one in a thousand potential cases was prevented through genetic screening.
- To end on another wild note, scientists have recently learned how to program somatic cells from a person’s body (for instance, skin cells) to become eggs or sperm instead. This raises the possibility not only for fertility treatments for people who can’t produce eggs or sperm, but even that same-sex couples might someday be able to have children belonging genetically to both of them.
Obviously, a ton of fascinating information in this book, and it’s highly readable for the general public, interspersing scientific information with stories from history and the author’s own experiences. While I was left with a few questions about some of this information, it was a great read and one I would definitely recommend. I picked up the recommendation by reading The Lost Family, which cites this one frequently, and which is also absolutely worth reading for its human-interest stories about heredity.
Below, some wild and fascinating things I learned from this book:
- You get 50% of your genes from each parent, but within the parents’ egg and sperm cells, meiosis scrambles up the DNA they received from each of their parents—meaning, your mom doesn’t necessarily give you exactly half of what she received from each of her parents. Thus, you might be more genetically similar to some grandparents than others. Siblings on average share 50% of their DNA, but in reality, siblings have been found with ranges from 37-62%.
- For the same reason, the further someone is from you on your family tree, the less likely you are to share any DNA at all (at least, anything recognizably individual; 99%+ of the human genome, after all, is shared by all humans). Among third cousins, 1% share no individual DNA. Among fourth cousins, it’s 25%.
- And the same holds true with ancestors: the further back you go, the greater the chance that no recognizable individual segments of DNA come from any particular ancestor. Go back 10 generations (roughly 250-300 years) and there’s a 46% chance you are not “related” to any given ancestor at all.
- We think of our ancestry as a forking tree, with no overlap. The problem is, go back one or two thousand years, and the number of individual forks representing your ancestors adds up to more people than have ever lived. Mathematically, all of our ancestors had to be related to each other.
- Mathematical models have also shown that, within a population (say, people of European descent), if you go back 1000 years, anyone who has any descendants living today is an ancestor of all people in that population living today. And that five thousand years ago, anyone with any living descendants is an ancestor of all living people. [I was disappointed that the author didn’t question this, because it’s obviously untrue. Native American and Pacific Islander populations left the Old World more than 5000 years ago, and have only been in contact for the last 200-500 years. Even if all Native Americans and Pacific Islanders alive today have since acquired Old World ancestry—which another study in the book assumes not to be the case, and the author also doesn’t question that one—I think it’s certainly fair to say that in the last few centuries, every European, African and Asian person has not acquired both Native American and Polynesian ancestry.]
- The oldest modern human fossils in Europe, from about 45,000 years ago, show no genetic indication of any relation to modern Europeans, whose DNA is an amalgamation of several later groups of migrants. These oldest Europeans, genetically, appear to have come from another continent entirely and vanished 37,000 years ago.
- Meanwhile, modern humans bear traces of Neanderthal DNA: about 0.08-0.34% for Africans, and 1-1.4% for non-Africans. Other ancient Neanderthal relatives, Denisovans, are also still around in our DNA, with some Pacific populations having up to 5% from this group, while East Asians and Native Americans carry noticeable amounts of Denisovan DNA as well. (So, oddly, does the book’s European-descended author!)
- A weird factoid from twin studies: twins are often misclassified as fraternal vs. identical. In one study in the Netherlands, 19% of parents gave the wrong answer. Misclassified identical twins, however, are just as similar to each other as correctly classified identical twins.
- Once a person is conceived, cells continue to divide—and there’s a possibility for mutation at any point in that process. (Happily, we set aside our egg and sperm cells early, so these mutations generally don’t make it to our children.) Thus, a person can be a “mosaic,” having different cells in the body coming from different lineages—which can cause diseases, or patchwork skin pigmentation, or make no difference at all. In fact, everyone has some mutations in their cell DNA. Mosaicism can also cure diseases, as the cells with a working version of a gene take over from the bad ones.
- Even freakier: by the time we’re born, our cells may not be entirely our own. Twins sharing a womb swap cells back and forth, as was first discovered in a blood donor who had two blood types. As it turned out, some of her blood also had Y chromosomes. Turns out, she’d had a twin who died soon after birth, but his blood lived on in her.
- Mothers and babies also exchange cells, despite the mechanisms that are supposed to prevent this. One study of girls found that 13% had at least some Y chromosomes in their blood, presumably from their brothers (or fetuses that never made it), maintained in the mother’s body and then passed on to their daughters.
- And those stem cells that get into the mother’s body? They can stay forever. One theory is that these “foreign” cells may contribute to higher rates of autoimmune disease among women. But in an incredible twist, because these are stem cells, they can also pick up new roles in her body—even healing it. In one truly wild case, a woman with hepatitis had an entire lobe of her liver regrown with Y chromosome-bearing cells, whose paternity was traced to her boyfriend. Turns out, she’d had an abortion years before—but the male fetus’s stem cells stuck around and made themselves useful. Meanwhile, one study, involving autopsies of elderly women, found Y chromosome cells in the brains of 63% of them.
- Then there are the “chimeras” resulting from twins merging in the early stages of embryonic development. When the twins are male and female, an intersex child can result, but with same-sex twins it tends to go unnoticed. One American woman almost lost custody of her four children when DNA tests showed that she wasn’t their mother—as it turned out, genetically, her reproductive system belonged to a different person (her unborn sister!) from the rest of her body. As far as most of her body was concerned, she was her children’s aunt despite having conceived and given birth to them. [The book does not address why Child Protective Services would have removed her children to foster care over this, but hooray American officialdom.] One has to wonder: how many men have gotten similarly negative results on paternity tests, but without the reassurance of knowing the kids came out of their body, assumed betrayal rather than hunting down the truth?
- Then, of course, by the numbers only half of the cells in our body are even human—the rest are microbes along for the ride. (Human cells are far bigger than microbes, though, so by weight we’re much more human than that!) We pick up our microbiome all over the place as small children: not just from our parents (though we start picking it up in the birth canal and from our mothers’ milk, and many strains of bacteria are highly heritable), but also from other people we’re around and whatever we put in our mouths. The human microbiome is wildly diverse: one study of the microbes in people’s navels found dozens in each person, and not a single microbe common to all.
- Meanwhile, the mitochondria in the cells of all living things appears to have originally been a microbe itself, whose symbiotic relationship with other cells led to becoming a part of them. This is why mitochondria has its own DNA (in humans, passed on only from the mother).
- Cancer can be contagious: a facial tumor killing Tasmanian devils is traceable to a single devil, and the animals spread it by biting each other’s faces in fights. Likewise, a genital tumor in dogs is traceable back thousands of years. Only a couple of cases of contagious cancer have been reported in humans; preventing this may be one reason why our bodies react so negatively to transplants from other people.
- CRISPR gene editing carries the possibility to transform populations, but it’s not as simple as you might think. Many mutations naturally die out, but a “gene drive” (a gene programmed to destroy competing versions, which can also occur in the wild) can prevent that. Scientists are experimenting with programming mosquitoes to not pass on malaria—but cautiously, knowing the ecological catastrophes that have resulted from releasing new organisms into an environment in the past.
- We also shouldn’t think that CRISPR for humans, should it become available for germline editing, would immediately transform the gene pool, even if the edited genes happen to be passed on to the recipients’ descendants (a big “if” for all the reasons seen above). For instance, pre-implantation genetic diagnosis of human embryos is available now for those undergoing in vitro fertilization, and generally used to avoid passing on hereditary diseases. However, with Huntington’s disease (which any parent would want to prevent), from 2002-2012, only one in a thousand potential cases was prevented through genetic screening.
- To end on another wild note, scientists have recently learned how to program somatic cells from a person’s body (for instance, skin cells) to become eggs or sperm instead. This raises the possibility not only for fertility treatments for people who can’t produce eggs or sperm, but even that same-sex couples might someday be able to have children belonging genetically to both of them.
Obviously, a ton of fascinating information in this book, and it’s highly readable for the general public, interspersing scientific information with stories from history and the author’s own experiences. While I was left with a few questions about some of this information, it was a great read and one I would definitely recommend. I picked up the recommendation by reading The Lost Family, which cites this one frequently, and which is also absolutely worth reading for its human-interest stories about heredity.
June 7, 2018
If you haven't been following or reading any news on genetics research, then this is an excellent primer, but if you do follow the science pages, there isn't much that is new in here. It's all interesting, but it's written by a reporter on science so none of it is firsthand research and the book isn't coherent enough to be memorable
January 23, 2021
Check out my review on Booktube!
November 19, 2024
Excellent book on heredity, specifically because Carl Zimmer focuses on deconstructing the artificial simplistically rigid common understanding of how genetics works. He emphasizes the exceptions and demonstrates heredity is almost always more complex than you think.
July 8, 2018
Heredity is the sum of all the previous environments and the current environment we were thrown into. Who we are as a species and as individuals is far more complicated than just our genes. Mendel’s law is a suggestion more than a law. This book lays the ground work for each of those assertions and steps the listener through some of the history of our understanding of the subject and reviews some of the current new research that has been transpiring over the last five years or so.
Humans are special: we culturally pass on racism, bigotry, misogyny and superstition mimetically. The racist premises in the ‘Bell Curve’ or Nicholas Wade’s last book are best ignored rather than refuted since they are groundless. The author doesn’t mention either book or author but he does spend a lot of time refuting their absurdities inherent in their deterministic genetic fallacies.
Racist and their ilk are going to hate. They will always have their reasons for hating the other just for the sake of making themselves appear superior to themselves and their select cohorts. Science has moved past that trash type thinking and this book lays out the case with fairly familiar concepts and stories.
Most of what was in this book seemed to have been in other books that I’ve read recently, and the parts that weren’t in the other books I’ve already read about in Science News or Scientific American. For those who are still in a ‘nature v. nurture’ deterministic paradigm and think biology through genes alone determines destiny this book will give them the background they need to move ahead. For all others, who realize that heredity is dependent on all of our previous environments (both as a species and as individuals and within the genome, the cells, the womb and the polis) and our current environment and experiences this book will be mostly superfluous since that is the main theme for this book.
Humans are special: we culturally pass on racism, bigotry, misogyny and superstition mimetically. The racist premises in the ‘Bell Curve’ or Nicholas Wade’s last book are best ignored rather than refuted since they are groundless. The author doesn’t mention either book or author but he does spend a lot of time refuting their absurdities inherent in their deterministic genetic fallacies.
Racist and their ilk are going to hate. They will always have their reasons for hating the other just for the sake of making themselves appear superior to themselves and their select cohorts. Science has moved past that trash type thinking and this book lays out the case with fairly familiar concepts and stories.
Most of what was in this book seemed to have been in other books that I’ve read recently, and the parts that weren’t in the other books I’ve already read about in Science News or Scientific American. For those who are still in a ‘nature v. nurture’ deterministic paradigm and think biology through genes alone determines destiny this book will give them the background they need to move ahead. For all others, who realize that heredity is dependent on all of our previous environments (both as a species and as individuals and within the genome, the cells, the womb and the polis) and our current environment and experiences this book will be mostly superfluous since that is the main theme for this book.
October 13, 2018
This science writing pulls the reader deeper and deeper into the amazing world we live in, it never gets dull or dry even when describing meiosis. Zimmer weaves historical and contemporary scientific research to create a work which you want to engage with. Who’d have thought that Mendel’s messing around with peas would lead eventually to the horrors of Hitler’s eugenics programs? Who knew that the sloppy research which lead to the published book about the so-called Kallikak family could have such devastating world stage consequences? Even our own Reginald Mungomery gets a mention, the bloke who came up with the idea to bring cane toads to Australia to eat the beetles destroying cane fields, scientists and biologists have been trying to find a solution to that mistake ever since. This is a fascinating book and I recommend it to anyone who has an interest in who we are and where our world is going: Zimmer’s explanation of global warming and the consequences the planet inevitably faces if we don’t stop releasing carbon into the atmosphere is clear and indisputable. A terrific read.
June 20, 2019
5 stars for the interesting content but 3 for the writing.
This was an interesting book, full of information from the very early research on heredity (Mendel as such) to the very current research using CRISPR. He discussed the ethical issues involved, including eugenics, the treatment of people with genetic disorders, and the implications of genetic research. I also appreciated the discussion of cultural heredity. I feel like I learned a great deal of information!
However, the writing was overly detailed and very long. It was a bear to get through. I'm very glad I read it but also very relieved that it's done.
This was an interesting book, full of information from the very early research on heredity (Mendel as such) to the very current research using CRISPR. He discussed the ethical issues involved, including eugenics, the treatment of people with genetic disorders, and the implications of genetic research. I also appreciated the discussion of cultural heredity. I feel like I learned a great deal of information!
However, the writing was overly detailed and very long. It was a bear to get through. I'm very glad I read it but also very relieved that it's done.
December 11, 2018
An absolutely fascinating read about heredity! It is jam packed with information about the history of genetics and modern scientific advances in the field. The writing style is magnetic and accessible!
I listened to this on audio as it was available on Scribd. I cannot wait to buy the ebook to re-visit the text and make notes. Highly recommend to anyone interested in narrative science writing!
I listened to this on audio as it was available on Scribd. I cannot wait to buy the ebook to re-visit the text and make notes. Highly recommend to anyone interested in narrative science writing!
May 20, 2018
An amazing and well researched book. Takes us through the history and research of heredity from
first works to today. It was so interesting to know where we started and how little we knew about heredity not that long ago. Some scientific researchers got it right and others drew wrong conclusions which may be forgivable for the time period but caused so much harm. There were certainly many ethical dilemmas that came in strong. Although it includes studies and scientific outcomes it is easy to read and understand the works and conclusions presented. This is an all inclusive study in who we are where we come from and how our genes and environment come together to make us who we are. Engaging - as it made me look at my own family and especially siblings to observe what traits we share with each other and our parents. This is the rare book for me that would get 100 out of 10 stars as where else would you get so much information in an easily read storytelling format in one book? I could open this book in any place randomly and follow the topic at hand immediately. A good read.
first works to today. It was so interesting to know where we started and how little we knew about heredity not that long ago. Some scientific researchers got it right and others drew wrong conclusions which may be forgivable for the time period but caused so much harm. There were certainly many ethical dilemmas that came in strong. Although it includes studies and scientific outcomes it is easy to read and understand the works and conclusions presented. This is an all inclusive study in who we are where we come from and how our genes and environment come together to make us who we are. Engaging - as it made me look at my own family and especially siblings to observe what traits we share with each other and our parents. This is the rare book for me that would get 100 out of 10 stars as where else would you get so much information in an easily read storytelling format in one book? I could open this book in any place randomly and follow the topic at hand immediately. A good read.
November 23, 2018
She has Her Mother's Laugh is the second book on similar topics I've read recently. The other book is The Gene: An Intimate History. There is some overlap, such as history of genetics from Aristotle to Darwin, Lamarck and Mendel, and Eugenics movement that had lead to The Holocaust, but enough difference makes it worth to read both books. I hope I have learned a lot about the history, single-gene diseases (Huntington's disease, PKU), the concept of race in genetic sense, polygenic disease (schizophrenia) and polygenic traits (height, intelligence), mitochondria, CRISPR, epigenetics, gene-therapy and gene-drive. In a way, the two books are complimentary to each other. A non-professional reader like me can get a better coverage from different aspects. Each book has different focus. For example, the discovery of DNA double Helix structure, Genentech and the first genetically engineered drug are detailed in The Gene, but briefly mentioned in She Has Her Mother's Laugh. Zimmer has better coverage on epigenetics and gene-drive, as well as ethical issues associated with altering human heredity.
The titles say it all--Mukherjee's book is about genes, while Zimmer discusses heredity.
She Has Her Mother's Laugh discusses not only human heredity, but also plants and animals. Luther Burbank has one chapter. Another chapter is about Tasmania Devil and their contagious cancer. Human heredity should include culture. The author's attempt is clear: to paint a bigger picture of heredity on the earth. To save earth from our own destruction, human race needs to think heredity out of our own present genes, but also genes which will populate the world in the future and what a future world we'll have to leave to our offsprings.
Several stories told in the book deeply moved me:
-- The story of Emma Wolverton
-- Peal S. Buck and her daughter Carol
The overtone of the book is somewhat uplifting: our future is not as doomed as some (including me) might say. Even we are unsure about the consequences, we still do it anyway--to tamper heredity, the nature's sanctuary, with caution. How much caution one must exert? Will we be burnt to death like Phaethon?
The author says we human are the only animal (except very few exceptions) capable of and very good at teaching and social learning. Are We Smart Enough to Know How Smart Animals Are? is a better source for such topic.
The titles say it all--Mukherjee's book is about genes, while Zimmer discusses heredity.
She Has Her Mother's Laugh discusses not only human heredity, but also plants and animals. Luther Burbank has one chapter. Another chapter is about Tasmania Devil and their contagious cancer. Human heredity should include culture. The author's attempt is clear: to paint a bigger picture of heredity on the earth. To save earth from our own destruction, human race needs to think heredity out of our own present genes, but also genes which will populate the world in the future and what a future world we'll have to leave to our offsprings.
Several stories told in the book deeply moved me:
-- The story of Emma Wolverton
-- Peal S. Buck and her daughter Carol
The overtone of the book is somewhat uplifting: our future is not as doomed as some (including me) might say. Even we are unsure about the consequences, we still do it anyway--to tamper heredity, the nature's sanctuary, with caution. How much caution one must exert? Will we be burnt to death like Phaethon?
The author says we human are the only animal (except very few exceptions) capable of and very good at teaching and social learning. Are We Smart Enough to Know How Smart Animals Are? is a better source for such topic.
August 24, 2020
Stupendous immersive journalism on the part of author Carl Zimmer. Great historical storytelling. Great science writing. Engaging and highly educational.
It’s time for all of us to get up to speed on heredity, bioethics and the gene editing revolution or risk waking up in a near future that is much stranger than science fiction.
The last 20 years have been a golden era in neuroscience. We are light years ahead of ware we were in 2000 in terms of what we now understand about the brain.
I know that people have been making this (hitherto empty) claim for a while now.
But...
The next 20 years are going to be all about genome wide association studies, polygenic scores, and CRISPR.
One can’t help but think about Pandora’s box, the flight of Icarus, the fate of prometheus and castigation from the garden.
The ancients were highly circumspect of playing god and fucking with nature. But the gene genie is definitely out of the bottle. We’re obviously WAY past the point of no return.
Let’s all hope this goes well.
At the minimum.
It’s going to be FUH KING interesting.
Great Book!
It’s time for all of us to get up to speed on heredity, bioethics and the gene editing revolution or risk waking up in a near future that is much stranger than science fiction.
The last 20 years have been a golden era in neuroscience. We are light years ahead of ware we were in 2000 in terms of what we now understand about the brain.
I know that people have been making this (hitherto empty) claim for a while now.
But...
The next 20 years are going to be all about genome wide association studies, polygenic scores, and CRISPR.
One can’t help but think about Pandora’s box, the flight of Icarus, the fate of prometheus and castigation from the garden.
The ancients were highly circumspect of playing god and fucking with nature. But the gene genie is definitely out of the bottle. We’re obviously WAY past the point of no return.
Let’s all hope this goes well.
At the minimum.
It’s going to be FUH KING interesting.
Great Book!
July 31, 2018
This book badly needed more editing. There's interesting stuff here, but it's lost amidst Zimmer's long, rambling detours into far less interesting subjects. Even when he's talking about interesting stuff, his writing is very wordy. I had to keep fighting the instinct to grab a pen and cross out words, because there are so many in here that are unnecessary.
July 5, 2019
This is a popular survey of the field of heredity, from genes to memes, from ancient folklore to the future potential and pitfalls of CRISPR.
March 12, 2019
The most important decision you can make in your life is who to have children with. This is understood more or less unconsciously by practically everyone, but the true nature of heredity - precisely what traits we inherit from our parents, and how we bequeath them in turn to our own children - is far more complex and subtle than we give it credit for. Zimmer traces our conception of heredity from one kind of ignorance to another, from our historical innocence of its genetic basis to our current incomprehension of what the ultimate consequences of our newfound power over it will be now that we have powerful tools like CRISPR. He does a great job balancing the pop sci elements of genetics 101 with the more complex cultural consequences at each stage of our understanding, so as concepts like X-inactivation, mosaicism, or epigenetics get discovered, you get crucial context as to how people used that new knowledge for both good and ill. The word "eugenics" casts a long shadow over our current attempts to consciously affect how our own heredity works, as it should, but the incandescence of real scientific knowledge is enough, or should be, to give us confidence that as we begin to use genetic engineering to deliberately reshape our genes that we don't have to simply repeat the old bigoted mistakes of the past. Our DNA might blindly attempt to replicate itself, but we don't have to, and a clear-eyed assessment of the possibilities in front of us should give us a great deal of optimism for our descendants.
The first genetics class I took was in 7th grade, and the Darwin vs Lamarck debate was one of the first things we covered. I often take a dim and impatient view of science classes that insist on walking students all the way back through the buried strata of ancient debates like that - much like "ontogeny recapitulates phylogeny", in Ernst Haeckel's famous line, most intro classes force students to recapitulate the history of the development of the subject matter by dredging up lots of discarded hypotheses - but genetics is complicated enough to be worthy of a comprehensive review, since some aspects of Lamarck's hypothesis are still being debated. I'm always amazed how ancient peoples could simultaneously spend hundreds or thousands of years patiently turning teosinte into corn or wolves into sheepdogs, yet be foggy on what exactly children share with their parents or why specifically it might be unwise to follow in your ancestor's footsteps and marry your first cousin, or think it was plausible that giraffes have long necks due to stretching. Pioneers of fruit and vegetable breeding like Luther Burbank, or even Gregor Mendel himself, had to spend an ungodly number of hours untangling phenotypes, proposing, rejecting, and concocting ever more elaborate hypotheses to explain why successive batches of peas and raspberries exhibited maddening almost-regularities, so retracing their thought patterns is still valuable and relevant. I particularly sympathized with Mendel, since in class when we learned about Punnett squares, the simple example of a dominant/recessive trait we were given was eye color. This confused me since both of my parents have green eyes yet I and my two siblings all have brown eyes. Theory destroyed? No; this is perfectly explicable given that eye color is in reality controlled by multiple genes, but if I were a 19th century monk trying to figure it out I'd have thought it was quite improbable given my naive monogenetic heterozygotic model.
So in that light it's not so surprising that the ideology behind inbred dynasties like the Ptolemies, Hapsburgs, or Romanovs lasted so long: if you want your children to inherit "royalty", then the more royals in their lineage the better! And of course the notion of heredity has been used to justify not only the continued rule of the strong, but also the subjugation of the weak, such as in the awful cases of the so-called "feeble-minded" individuals Zimmer profiles who were sterilized or otherwise dissuaded from having children due to stupid ideas about inherited cretinism. Intelligence remains the most hotly-debated form of heredity, since both nature and nurture seem important. Most people, including geneticists, freely acknowledge that there is at least some environmental influence, but it doesn't seem like anyone really believes that the choice of person who provides the other half of your child's genes is completely irrelevant to their welfare. If who you had kids with truly didn't matter at all, the world would look a lot different! This knowledge that your partner matters is also true for inherited diseases, as seen by the many techniques to reduce the chances of passing on congenital conditions via genetic testing and deliberate matching. A more innocuous trait like height, which is no longer as adaptive as it used to be (instead of a reliable marker of superior health, now that basically everyone has enough to eat it usually just signifies a difficulty fitting into tiny sports cars or airplane seats), falls somewhere in between, and so it took polymath Francis Galton, Charles Darwin's cousin, many hours of staring at height charts to come up with innovative statistical concepts like regression to the mean in order to explain why the children of the tall were not always the size of their parents, or how the odd pair of short people often produced average children. He was also the guy who first systematically fitted human attributes to Gaussian distributions, vastly improving our ability to analyze psychological and behavioral traits.
But many of the more fascinating aspects of heredity had to wait for modern science to come around in order to be studied in more detail. The discovery that not all cells are the same (mitosis-using somatic cells which make up your body vs meiosis-using zygotic cells that make up sperm and eggs) was fairly recent, as was the distinction between totipotent cells (which can turn into anything), pluripotent cells (which can become any type of somatic cell), and multipotent cells (which are limited to specific cell genres). Also interesting to me were things like lyonization/X-inactivation, where clumps of cells decide at once whether or not to express certain traits and produce things like calico patterns in cats, or the distinction between mosaicism (different cell lineages inside the same organism, so your body is generating multiple lines of mutation within yourself) vs chimerism (where your body can include cells from other organisms, meaning a mother can actually back-inherit genes from her baby via reverse travel up through the placenta). The idea that your body depends on other organisms that you don't share any DNA with - things that are in you but not of you - is worth a ponder. Zimmer got the bacteria in his belly button analyzed, and found that he had 53 distinct species present, including 17 species that hadn't been seen before. Your specific intestinal ecosystem of gut bacteria is crucial for digestion. Less whimsically, mitochondria, which are crucial because they provide the body's energy via conversion of oxygen and sugar into ATP, are also separate organisms, yet are inherited almost but not quite entirely exclusively from our mothers (ancestry services like 23andMe use mitochondrial DNA to infer maternal lineage). He also relates the fascinating case of a form of infectious canine cancer which has been spreading from dog to dog for an almost unfathomably long time:
"Contagious cancer is not all that different from an ordinary tumor that becomes metastatic and spreads from one organ to another. The new organ is, in effect, another animal. But unlike ordinary tumors, contagious cancers no longer face an inescapable death. Instead of gaining a few years' worth of mutations, they can gain centuries of them. After eleven thousand years circulating among dogs, for example, CTVT has acquired an impressive arsenal of mutations in genes linked to immune surveillance. And just like ordinary cancer cells, CTVT cells have stolen mitochondria to replace their own. The only difference is that they steal mitochondria from a series of dogs - at least five different dogs over the past two thousand years. From the days of the Roman Empire onward, CTVT has recharged itself like a vampire, with the youth of its canine victims."
More difficult for people to accept was the idea that the same DNA can be expressed differently based on environmental stimulus; epigenetics and gene expression seemed dangerously close to the ideas of Lamarck or Lysenko, the Soviet charlatan who thought that you could breed winter-resistant wheat by sowing the seeds in snow. Zimmer quotes geneticist Keven Mitchell expressing extreme skepticism that your life experiences as stored in your neurons could affect your sperm/eggs in order to thereby affect your children's neurons:
"For transgeneration epigenetic transmission of behaviour to occur in mammals," he wrote, "here's what would have to happen:
Experience --> Brain state --> Altered gene expression in some specific neurons (so far so good, all systems working normally)-->Transmission of information to germline (how? what signal?) --> Instantiation of epigenetic states in gametes (how?) --> Propagation of state through genomic epigenetic "rebooting," embryogenesis and subsequent brain development (hmm...) --> Translation of state into altered gene expression in specific neurons (ah now, c'mon) --> Altered sensitivity of specific neural circuits, as if the animal had had the same experience itself --> Altered behaviour now reflecting experience of parents, which somehow over-rides plasticity and epigenetic responsiveness of those same circuits to the behaviour of the animal itself (which supposedly kicked off the whole cascade in the first place)"
Put that way, it does sound science fictional, like the genetic memory in the Dune series. Particularly that last part: if our minds are shaped by our parents' life experiences, how would we then pass down our own experiences to our children in turn without our experiences being overridden, unless all we're doing is transmitting Nth generation photocopies of particularly vivid days in the lives of our cavemen ancestors ceaselessly unto the future? But, fascinatingly, it seems that it is actually possible for plants to inherit certain gene expressions of their ancestors; whether due to patterns of DNA methylation (coatings around DNA that affect their transcription), different RNA interactions during DNA replication, or the distinct sequences of plant germ cells transforming into somatic cells, plants seem to have different tools of heredity than animals do.
Zimmer uses those teases of cellular recollection to segue into a brief discussion of the distinctly human tools of mimesis, social learning, and culture that allow us to pass on far more than our genes to the next generation. Joe Henrich's book The Secret of Our Success is my current favorite book on cultural evolution, and some of Henrich's work on importance of our cultural heritage, which Zimmer estimates as extending back to about 7 million years (!), is cited here. But it's the possibilities of genetic engineering, particularly new tools like CRISPR, that are the most exciting, as the ability to selectively edit individual genes to precisely insert desired traits opens up all kinds of obvious avenues for genetic improvement. I don't think anyone but the most determined GMO conspiracy theorist would have issues with the kind of accelerated horticulture that plant scientist Zachary Lippmann wants to do to ground cherries, like Luther Burbank on fast forward:
"He would edit genes that controlled when the fruits fell from the bushes, so that farmers wouldn't have to rummage on the ground for them. He would make a change to get the plants to ripen their fruits in batches rather than a few at a time. He would adjust the plants' response to sunlight so they would start producing fruit early in the growing season. They would grow to a fixed height so that farmers could use machines to gather them."
But people are rightly more worried about what this power could mean for human beings. We still have some time to ponder the ethical boundaries of deliberate gene editing, because it's unfortunately not quite as simple as cutting and pasting genes to make ourselves supermen, though we have already taken some steps into that world. In addition to the fact that CRISPR techniques themselves are still new and unperfected (Zimmer relates the example of some edited female mosquitoes that were somehow able to revert their CRISPR edits during their development from eggs; see also the saga of Chinese scientist He Jiankui from a month ago, well after this book was published), many of the traits we're most interested in depend on thousands of genes working together in ways that are still not well understood. Furthermore, even were we to develop a gene drive that would spread some new ability throughout humanity as fast as we're able to reproduce, there are still countless potential unintended consequences of a mutagenic chain reaction. Personally I'm all for getting rid of genetic diseases, and even conscious editing to encourage health and intelligence, but we have a while before we get there. The dream of a completely deterministic heredity has not yet been achieved, and so in the meantime we can still marvel at how the characteristics that we find most attractive or unique in each other get carried on to each new generation. "Life finds a way" indeed.
The first genetics class I took was in 7th grade, and the Darwin vs Lamarck debate was one of the first things we covered. I often take a dim and impatient view of science classes that insist on walking students all the way back through the buried strata of ancient debates like that - much like "ontogeny recapitulates phylogeny", in Ernst Haeckel's famous line, most intro classes force students to recapitulate the history of the development of the subject matter by dredging up lots of discarded hypotheses - but genetics is complicated enough to be worthy of a comprehensive review, since some aspects of Lamarck's hypothesis are still being debated. I'm always amazed how ancient peoples could simultaneously spend hundreds or thousands of years patiently turning teosinte into corn or wolves into sheepdogs, yet be foggy on what exactly children share with their parents or why specifically it might be unwise to follow in your ancestor's footsteps and marry your first cousin, or think it was plausible that giraffes have long necks due to stretching. Pioneers of fruit and vegetable breeding like Luther Burbank, or even Gregor Mendel himself, had to spend an ungodly number of hours untangling phenotypes, proposing, rejecting, and concocting ever more elaborate hypotheses to explain why successive batches of peas and raspberries exhibited maddening almost-regularities, so retracing their thought patterns is still valuable and relevant. I particularly sympathized with Mendel, since in class when we learned about Punnett squares, the simple example of a dominant/recessive trait we were given was eye color. This confused me since both of my parents have green eyes yet I and my two siblings all have brown eyes. Theory destroyed? No; this is perfectly explicable given that eye color is in reality controlled by multiple genes, but if I were a 19th century monk trying to figure it out I'd have thought it was quite improbable given my naive monogenetic heterozygotic model.
So in that light it's not so surprising that the ideology behind inbred dynasties like the Ptolemies, Hapsburgs, or Romanovs lasted so long: if you want your children to inherit "royalty", then the more royals in their lineage the better! And of course the notion of heredity has been used to justify not only the continued rule of the strong, but also the subjugation of the weak, such as in the awful cases of the so-called "feeble-minded" individuals Zimmer profiles who were sterilized or otherwise dissuaded from having children due to stupid ideas about inherited cretinism. Intelligence remains the most hotly-debated form of heredity, since both nature and nurture seem important. Most people, including geneticists, freely acknowledge that there is at least some environmental influence, but it doesn't seem like anyone really believes that the choice of person who provides the other half of your child's genes is completely irrelevant to their welfare. If who you had kids with truly didn't matter at all, the world would look a lot different! This knowledge that your partner matters is also true for inherited diseases, as seen by the many techniques to reduce the chances of passing on congenital conditions via genetic testing and deliberate matching. A more innocuous trait like height, which is no longer as adaptive as it used to be (instead of a reliable marker of superior health, now that basically everyone has enough to eat it usually just signifies a difficulty fitting into tiny sports cars or airplane seats), falls somewhere in between, and so it took polymath Francis Galton, Charles Darwin's cousin, many hours of staring at height charts to come up with innovative statistical concepts like regression to the mean in order to explain why the children of the tall were not always the size of their parents, or how the odd pair of short people often produced average children. He was also the guy who first systematically fitted human attributes to Gaussian distributions, vastly improving our ability to analyze psychological and behavioral traits.
But many of the more fascinating aspects of heredity had to wait for modern science to come around in order to be studied in more detail. The discovery that not all cells are the same (mitosis-using somatic cells which make up your body vs meiosis-using zygotic cells that make up sperm and eggs) was fairly recent, as was the distinction between totipotent cells (which can turn into anything), pluripotent cells (which can become any type of somatic cell), and multipotent cells (which are limited to specific cell genres). Also interesting to me were things like lyonization/X-inactivation, where clumps of cells decide at once whether or not to express certain traits and produce things like calico patterns in cats, or the distinction between mosaicism (different cell lineages inside the same organism, so your body is generating multiple lines of mutation within yourself) vs chimerism (where your body can include cells from other organisms, meaning a mother can actually back-inherit genes from her baby via reverse travel up through the placenta). The idea that your body depends on other organisms that you don't share any DNA with - things that are in you but not of you - is worth a ponder. Zimmer got the bacteria in his belly button analyzed, and found that he had 53 distinct species present, including 17 species that hadn't been seen before. Your specific intestinal ecosystem of gut bacteria is crucial for digestion. Less whimsically, mitochondria, which are crucial because they provide the body's energy via conversion of oxygen and sugar into ATP, are also separate organisms, yet are inherited almost but not quite entirely exclusively from our mothers (ancestry services like 23andMe use mitochondrial DNA to infer maternal lineage). He also relates the fascinating case of a form of infectious canine cancer which has been spreading from dog to dog for an almost unfathomably long time:
"Contagious cancer is not all that different from an ordinary tumor that becomes metastatic and spreads from one organ to another. The new organ is, in effect, another animal. But unlike ordinary tumors, contagious cancers no longer face an inescapable death. Instead of gaining a few years' worth of mutations, they can gain centuries of them. After eleven thousand years circulating among dogs, for example, CTVT has acquired an impressive arsenal of mutations in genes linked to immune surveillance. And just like ordinary cancer cells, CTVT cells have stolen mitochondria to replace their own. The only difference is that they steal mitochondria from a series of dogs - at least five different dogs over the past two thousand years. From the days of the Roman Empire onward, CTVT has recharged itself like a vampire, with the youth of its canine victims."
More difficult for people to accept was the idea that the same DNA can be expressed differently based on environmental stimulus; epigenetics and gene expression seemed dangerously close to the ideas of Lamarck or Lysenko, the Soviet charlatan who thought that you could breed winter-resistant wheat by sowing the seeds in snow. Zimmer quotes geneticist Keven Mitchell expressing extreme skepticism that your life experiences as stored in your neurons could affect your sperm/eggs in order to thereby affect your children's neurons:
"For transgeneration epigenetic transmission of behaviour to occur in mammals," he wrote, "here's what would have to happen:
Experience --> Brain state --> Altered gene expression in some specific neurons (so far so good, all systems working normally)-->Transmission of information to germline (how? what signal?) --> Instantiation of epigenetic states in gametes (how?) --> Propagation of state through genomic epigenetic "rebooting," embryogenesis and subsequent brain development (hmm...) --> Translation of state into altered gene expression in specific neurons (ah now, c'mon) --> Altered sensitivity of specific neural circuits, as if the animal had had the same experience itself --> Altered behaviour now reflecting experience of parents, which somehow over-rides plasticity and epigenetic responsiveness of those same circuits to the behaviour of the animal itself (which supposedly kicked off the whole cascade in the first place)"
Put that way, it does sound science fictional, like the genetic memory in the Dune series. Particularly that last part: if our minds are shaped by our parents' life experiences, how would we then pass down our own experiences to our children in turn without our experiences being overridden, unless all we're doing is transmitting Nth generation photocopies of particularly vivid days in the lives of our cavemen ancestors ceaselessly unto the future? But, fascinatingly, it seems that it is actually possible for plants to inherit certain gene expressions of their ancestors; whether due to patterns of DNA methylation (coatings around DNA that affect their transcription), different RNA interactions during DNA replication, or the distinct sequences of plant germ cells transforming into somatic cells, plants seem to have different tools of heredity than animals do.
Zimmer uses those teases of cellular recollection to segue into a brief discussion of the distinctly human tools of mimesis, social learning, and culture that allow us to pass on far more than our genes to the next generation. Joe Henrich's book The Secret of Our Success is my current favorite book on cultural evolution, and some of Henrich's work on importance of our cultural heritage, which Zimmer estimates as extending back to about 7 million years (!), is cited here. But it's the possibilities of genetic engineering, particularly new tools like CRISPR, that are the most exciting, as the ability to selectively edit individual genes to precisely insert desired traits opens up all kinds of obvious avenues for genetic improvement. I don't think anyone but the most determined GMO conspiracy theorist would have issues with the kind of accelerated horticulture that plant scientist Zachary Lippmann wants to do to ground cherries, like Luther Burbank on fast forward:
"He would edit genes that controlled when the fruits fell from the bushes, so that farmers wouldn't have to rummage on the ground for them. He would make a change to get the plants to ripen their fruits in batches rather than a few at a time. He would adjust the plants' response to sunlight so they would start producing fruit early in the growing season. They would grow to a fixed height so that farmers could use machines to gather them."
But people are rightly more worried about what this power could mean for human beings. We still have some time to ponder the ethical boundaries of deliberate gene editing, because it's unfortunately not quite as simple as cutting and pasting genes to make ourselves supermen, though we have already taken some steps into that world. In addition to the fact that CRISPR techniques themselves are still new and unperfected (Zimmer relates the example of some edited female mosquitoes that were somehow able to revert their CRISPR edits during their development from eggs; see also the saga of Chinese scientist He Jiankui from a month ago, well after this book was published), many of the traits we're most interested in depend on thousands of genes working together in ways that are still not well understood. Furthermore, even were we to develop a gene drive that would spread some new ability throughout humanity as fast as we're able to reproduce, there are still countless potential unintended consequences of a mutagenic chain reaction. Personally I'm all for getting rid of genetic diseases, and even conscious editing to encourage health and intelligence, but we have a while before we get there. The dream of a completely deterministic heredity has not yet been achieved, and so in the meantime we can still marvel at how the characteristics that we find most attractive or unique in each other get carried on to each new generation. "Life finds a way" indeed.
December 7, 2018
One the best book I read this year, and definitely one of the best science books I read, ever.
Carl Zimmer is an amazing science writer. Besides having a very fluid and engaging narrative style, he is also a great researcher and is able to simplify concepts without diluting them and present to the reader in a comprehensive, engaging way.
The book tells many stories over the last two century about genetics: how various prominent historical science figure's work impacted the field of genetics and society, how the perceptions of the people over the history impacted what they wanted to see & believe regardless of their findings. He does a deep dive in the history of eugenics, the concept of race, history of evolution, discovery of genes and then DNAs as well as the recent developments around gene editing. He goes into the details of the history of some royal families and the genetics defects they ended up accumulating by marrying close relatives, the concept of feeblemindedness and how it ended up leading to most heinous crimes of the human history, the fascinating history of Luther Burbank ( The Wizard of Horticulture), who ended up creating more than 800 plant varieties in his lifetime, and the story of Pearl S. Buck's daughter and how she ended up being a prominent writer to support her.
History of science and medicine is so fascinating, and it can give us so many clues about life, society, and our inherent biases. It demonstrates that sometimes the smartest people make the biggest blunders due to the inherent beliefs and values they have. Zimmer is great to find such stories that would help to understand those biases and allows us to reflect and be mindful about our assumptions.
I enjoyed every minute of the book, and read/listened it with awe from time to time. It was a long read, but every minute of it was enjoyable.
Carl Zimmer is an amazing science writer. Besides having a very fluid and engaging narrative style, he is also a great researcher and is able to simplify concepts without diluting them and present to the reader in a comprehensive, engaging way.
The book tells many stories over the last two century about genetics: how various prominent historical science figure's work impacted the field of genetics and society, how the perceptions of the people over the history impacted what they wanted to see & believe regardless of their findings. He does a deep dive in the history of eugenics, the concept of race, history of evolution, discovery of genes and then DNAs as well as the recent developments around gene editing. He goes into the details of the history of some royal families and the genetics defects they ended up accumulating by marrying close relatives, the concept of feeblemindedness and how it ended up leading to most heinous crimes of the human history, the fascinating history of Luther Burbank ( The Wizard of Horticulture), who ended up creating more than 800 plant varieties in his lifetime, and the story of Pearl S. Buck's daughter and how she ended up being a prominent writer to support her.
History of science and medicine is so fascinating, and it can give us so many clues about life, society, and our inherent biases. It demonstrates that sometimes the smartest people make the biggest blunders due to the inherent beliefs and values they have. Zimmer is great to find such stories that would help to understand those biases and allows us to reflect and be mindful about our assumptions.
I enjoyed every minute of the book, and read/listened it with awe from time to time. It was a long read, but every minute of it was enjoyable.
December 14, 2018
When people meet my children I often hear comments along the lines of; he is just like you, your daughter reminds me so much of your wife and similar comments. And it is true, their genetic inheritance comes directly from me and my wife and the blend of our genes has made three very different and unique children. What gets passed on and how is the subject of this weighty tome.
In this very researched book, Zimmer takes us back through our genetic history to show how these fragments make up our very being. Of the trillions of cells in our bodies, those that contain our DNA make us who we are, what we look like, how our health will be and countless other factors. But there is more to it than that, our genetic code is not the only thing passed from mother to child, echoes of past event from our father and his parents can be seen in the code, we get our first immune system via the placenta and the various microbes that ensure that we can live as passed on too.
There is a fascinating chapter on Chimeras – these are people who carry more than one set of DNA. This was never thought to be possible, but after various anomalies including where a mother was witnessed giving birth to a child, the DNA test said that it wasn’t her child. The investigation into it discovered how DNA can transfer between non-identical twins after one dies in the womb. A mother can even absorb some of the DNA from the child she is carrying.
There is a wealth of information and details in this substantial, but still a very readable book. Not only does he consider where we have got to in our understanding on DNA, but he contemplates the future of inheritance and what heredity will mean in years to come. Even though I never did biology while at school, Zimmer manages to make this fairly substantial tome a straightforward book for readers like me.
In this very researched book, Zimmer takes us back through our genetic history to show how these fragments make up our very being. Of the trillions of cells in our bodies, those that contain our DNA make us who we are, what we look like, how our health will be and countless other factors. But there is more to it than that, our genetic code is not the only thing passed from mother to child, echoes of past event from our father and his parents can be seen in the code, we get our first immune system via the placenta and the various microbes that ensure that we can live as passed on too.
There is a fascinating chapter on Chimeras – these are people who carry more than one set of DNA. This was never thought to be possible, but after various anomalies including where a mother was witnessed giving birth to a child, the DNA test said that it wasn’t her child. The investigation into it discovered how DNA can transfer between non-identical twins after one dies in the womb. A mother can even absorb some of the DNA from the child she is carrying.
There is a wealth of information and details in this substantial, but still a very readable book. Not only does he consider where we have got to in our understanding on DNA, but he contemplates the future of inheritance and what heredity will mean in years to come. Even though I never did biology while at school, Zimmer manages to make this fairly substantial tome a straightforward book for readers like me.
September 9, 2021
চমৎকার একটি বই যা পাঠককে জেনেটিক্সের সেই শুরু থেকে খুবই সাম্প্রতিক সময় পর্যন্ত গুরুত্বপূর্ণ ধারণাগুলোর সাথে পরিচয় করিয়ে দেয়। সবচেয়ে অবাক হয়েছি যখন “অম্নিজেনিক মডেল”-এর দেখা পেয়েছি। এই মডেল এখনও প্রতিষ্ঠিত না, তবে গবেষকদের দৃষ্টি আকর্ষণ করা শুরু করেছে। এর প্রস্তাবক জোনাথন প্রিচার্ডের ল্যাবের সাথে আমাদের ল্যাবের কোলাবোরেশন থাকায় এই মডেলের সাথে আগে থেকেই পরিচিত ছিলাম, তবে এত দ্রুত জনপ্রিয় ধারার বইয়ে চলে আসবে ভাবতে পারিনি।
সত্যি বলতে, শুরুর দিকে বইটা সম্বন্ধে একটু সংশয়ী ছিলাম - মনে হয়েছিলো এটা কেবল তারাই বুঝতে পারবে আগে থেকেই যাদের মোলিক কিছু ধারণা আছে, একদম নতুনদের জন্য হয়তো না। কারণ জেনেটিক্স নিয়ে মোটামুটি সাধারণ ধারণা দিলেও সেগুলোর তাত্ত্বিক গভীরে যায়নি। হয়তো নিজে সেই বিষয়গুলো কিছু-কিছু জানি বলেই এরকম মনে হয়েছিলো। তবে পরে নিজের জন্যও নতুন কিছু বিষয় যখন এসেছে (যেমন - বাচ্চা থেকে মায়ের শরীরে জেনেটিক উপকরণ স্থানান্তর হওয়া, কাইমেরা বিষয়ক কিছু ধারণা, ইত্যাদি), তখন বুঝতে পেরেছি বর্ণণাগুলো নতুনদের জন্য বেশ সহজ ও আকর্ষণীয় হ��়েছে। হ্যাঁ, খুব গভীরে যায়নি - একথা সত্য, তবে একজন নবাগত মনে হয় এত গভীরে যেতে চায়ও না। তাই দিন শেষে নতুন কিছু শিখতে পেরে আমি কৃতজ্ঞ এ বইয়ের কাছে।
সত্যি বলতে, শুরুর দিকে বইটা সম্বন্ধে একটু সংশয়ী ছিলাম - মনে হয়েছিলো এটা কেবল তারাই বুঝতে পারবে আগে থেকেই যাদের মোলিক কিছু ধারণা আছে, একদম নতুনদের জন্য হয়তো না। কারণ জেনেটিক্স নিয়ে মোটামুটি সাধারণ ধারণা দিলেও সেগুলোর তাত্ত্বিক গভীরে যায়নি। হয়তো নিজে সেই বিষয়গুলো কিছু-কিছু জানি বলেই এরকম মনে হয়েছিলো। তবে পরে নিজের জন্যও নতুন কিছু বিষয় যখন এসেছে (যেমন - বাচ্চা থেকে মায়ের শরীরে জেনেটিক উপকরণ স্থানান্তর হওয়া, কাইমেরা বিষয়ক কিছু ধারণা, ইত্যাদি), তখন বুঝতে পেরেছি বর্ণণাগুলো নতুনদের জন্য বেশ সহজ ও আকর্ষণীয় হ��়েছে। হ্যাঁ, খুব গভীরে যায়নি - একথা সত্য, তবে একজন নবাগত মনে হয় এত গভীরে যেতে চায়ও না। তাই দিন শেষে নতুন কিছু শিখতে পেরে আমি কৃতজ্ঞ এ বইয়ের কাছে।
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