Carl Zimmer || The New Science of Heredity

So today we have Karl Zimmer on the podcast. Zimmer reports from the frontiers of biology, where scientists are expanding our understanding of life. Since two thousand and four, he has written about science for The New York Times, whereas

column Matter has appeared weekly since twenty thirteen. Zimmer has won many awards for his work, including the Stephen J. Goldprize, awarded by the Society for the Study of Evolution to recognize individuals whose sustained efforts have advanced public understanding of evolutionary science. Zimmer is the author of thirteen books about science, and his latest book is She Has Her Mother's Laugh The Power, Perversions and Potential of Heredity. Thanks for chatting

with me today, Carl. Thanks for having me. I remember when I was a wee grad student at Yale and you came to do I was so excited that I got selected to be in this little group of people to talk to the great Carl Zimmer about public science communication. Do you remember that? Like it was like we're talking like a decade ago. Yeah. I've been doing it every spring since with some Bale graduate students. Just you know,

the the interest is just getting stronger and stronger. I think grad students who are looking at a future in science, you know, realize that, you know, part of it is connecting with everybody else. They don't look at science purely as just collecting data. That's right. And I remember listening to you talk and thinking to myself, I want to

do what that guy does someday, you know. So I see, really we're in an inspiration You're the way that you write, The way that you write is balanced, and I think that's what we need more of in the science communication world, is balance. Right, So this book. Let's talk about this book because it's an interesting sort of hybrid model because it's kind of reads like a novel in a way.

You know, it's kind of like a page turn and I want to start off with the word heredity, which is in your title, because you know, a lot of people think heredity and they think genetics, and could you please explain about why they're not synonymous in this book that you've written, genetics and heredity. Right, So the word genetics, you know, is actually a pretty young word. It's a little over one hundred years old, whereas the word heredity is thousands of years old. The oldest route that we

can trace it to is hereditass from Latin. And so we've been thinking about heredity in lots of different ways for a long time, long before the science of genetics came on the scene. And heredity means a lot of things to us. It means incredibly important things to us. It is how we connect ourselves to the past and to the future, and also how we define ourselves. You know, what is our blood? You know that in a way

that kind of says who we are. And genetics as a science came about as an attempt to answer the question of what is heredity, but a very particular version of heredity. In other words, in the eighteen hundreds, people like Charles Darwin's really started to conceptualize heritity as being some sort of physical substance on a microscopic scale that was being passed down from one generation to the next.

And I'd argue that, you know, genetics is a hugely important answer to what is heredity, but actually heredity is even bigger than that. It's not simply saying genes does

real disservice to heredity itself. It's a much bigger than that, and it really defines our intuitions about what connects us to the future in the past great and there's a lot of weirdness to heredity that stick to the standard story that a lot of people weren't even in like eighth grade biology class, right, you know, there's more of the story that whether you inherited your mother's lies, for instance. Right. Yeah.

I mean, I think that we're in this situation in the twenty first century where most people learn about genetics in grade school or high school and then that's about it, and they get about as far as mental and so we tend to think about heredity not just in terms of genes, but as single genes, as genes that are you know, totally dominant and recessive. And you know, if there's some trait, well you must have the gene for

that trait. And actually, you know, mental is a great place to start to understand redity, but it's a terrible place to stop because you know, if you take a

trait like height, for example, there's no height gene. There are thousands of genes that make proteins that are involved in lots of different things going on in our cells and between ourselves, and mutations to those thousands of genes can alter our height on average, so that you know, if you have a variant for one gene, you know that might on average, you know, increase people's height, you know,

maybe a millimeter. And so you know, to look at your parents or your grandparents and say like, oh, I'm you know, short because they're short, Well, yes, but they're actually you're actually talking about thousands of different genes and all these complex interactions between them just to talk about height, And that's really like the low hanging fruit when it

comes to talking about who we are. If you want to talk about things like personality or intelligence things like that, yeah, well then it's just you got to to step back and take a bigger view of reddity. And what's exciting is that actually, you know, scientists right now are starting to really grapple with heredity on that scale. You know, they can actually look at entire genomes and actually look at them at this a huge scale, using incredibly powerful

computers to get out these basic questions. So I wanted to share the excitement of the scientific progress that's happening right now. But in order to do that, you have to sort of sort of break out of that kind of high school genetics that is really was irrelevant. It was relevant one hundred years ago, it's not so relevant now.

Good Good, And you argue that we need a new definition of redity that takes into account some of the exciting recent discoveries such as Crisper and CAST nine gene editing, so as well as other technologists, and I'd like to just cover some of these new emerging techniquessnologies. Could you please explain some of the upcoming or what we currently

have in the technology terms of gene editing. Crisper is a gene editing technology which basically is a way to design molecules that are able to zero in on some particular spot in a genome, cut out a little section of DNA, and in some cases insert another stretch of DNA in the place of what was taken out. So you can think of it a bit like you know, searching through a Microsoft word document, highlighting a passage and then deleting it or pasting in something else. And where

are we at in that technology right now? How expensive is this technology? What do you sort of predict how many years till this becomes more widespread maybe even available to the general public. Well, you know, if you go to biology labs, it's in widespread use. I mean everybody's using it, okay, and you know they will use it for all sorts of different things. So, like, let's say you want to do an experiment to figure out which genes are essential for a cancer cell to grow aggressively

to be a cancer cell. You can just create a bunch of cell colonies and Petrie dishes and use crisper in each one of those to cut out a different gene and then you just see how well they grow after that. And so scientists have actually done this, you know, they've gone through and like, you know, twenty thousand or so genes and cut out everyone, and they've made up this list, this much shorter list of essential cancer genes and that is going to be a huge that's huge.

It's huge because then you know they're actually drug companies right now who are using these catalogs to say like, okay, like we're going to now look for cancer drugs that go after this particular gene. You know, nobody knew that this gene was essential for cancer. Now we know now we're going to go for it. So that's just one

example of what people using crisper for. I think where crisper gets its real excitement and maybe some anxiety for some people is the ability to use Crisper to make permanent, inherited changes in an organism. And so right now there's a lot of work going on with plants to use Crisper to tinker with the DNA of crops, for example, to make tomatoes that can grow in a shorter growing season.

For example, it turns out if you just cut out a tiny piece of DNA, which is just acts like a little sort of control switch to one gene, you can actually get them to grow better in more northern climates. So there's a case where you know, once you created that change with crisper, that can get passed down from generation to generation, and so you know, the possibility arises that you could do the same thing in animals, which

some people are experimenting with. The real controversy, of course, is what if you use this on humans exactly, and we build up to psychological traits and discuss those implications, would we be able to headit thousands of genes at the same time. Well, it's hard to look into the future and say exactly what gene editing will allow us to do in the future right now, No way, right right right now, Like single genes at this point, right yeah, yeah, it's very hard to do more than just one gene.

I mean, there have been some experiments where people have you know, altered a few genes at the same time, and there have been cases actually where people have been able to cut out, you know, many dozens of pieces of DNA at once. But that's I won't say it's cheating, but what they're doing in a case like that is that they're actually looking for almost identical sequences of DNA

and cutting them all out. This is actually a study where researchers wanted to make a breed of pigs that would be safer for using for possible growing organs for transplantation, and the problem with pigs is that they have certain stretches of DNA in their genome that are actually viruses that got embedded in their genome. Lots of species have this, but you don't want to get a pig transplant and then suddenly have it producing viruses inside of you that

that would be bad. But with Crisper, it looks like you can actually go in and just edit all of those out at once, and so it might be possible to produce a breed of pigs that was free of these what are called hodogenous retroviruses. That's so fascinating. We're like long way off from like psychiatrists, instead of prescribing SSRIs, prescribing CRISPER. Yeah, no, I that will. I don't want to say never, you never know, But I mean one thing I hope my book gets across is just what

an insanely complicated proposal that would be. Because when you talk about traits like intelligence or personality, you're talking about things that are certainly influenced by genes, but they are influenced again by thousands of genes. In each gene is playing a part that we don't understand at all, and you know, maybe one makes a protein that makes some particular connection between neurons, maybe another one is involved with

the molecules that act as signals between neurons. But how that translates to, you know, depression is we just do not know. We nowhere near making those sorts of connections from the genetic level to the level of how we experience life. And not only that, but these genes are working in an environment, and so you know, you may it's possible, you may have genes that may put you at risk for certain conditions as an adult, but only like if you grow up in a very stressful environment.

If you don't, then they're not a risk factor at all. So to say like, oh well, if we just change this spelling, then everything's fine totally misses the point when it comes to our psychology. Yeah, it's an excellent point. So you talk about some examples that Stephen J. Gould talked about similar examples in The Mismeasure of Man, so like the Calikak family story. I mean, you also talk about cirl Bert's fraud. You know, I would be gray

if you could just briefly summarize that. But my real question is that you know, the truth of the matter is, even though some of their work was really shoddy, I mean, modern science does confirm some of their hypotheses nevertheless, in the sense that there is a genetic contribution not deterministic, but probabilistic to intelligence and IQ right, it's kind of a baby in bathwater situation. I focus a lot in the book on as you mentioned, this book called the

Calikak Family. This was actually and I organized that chapter actually around a woman who was the subject of this book and was sort of involuntarily turned in kind of a poster child for eugenics. Her name was Emma Wolverton, and she was institutionalized in a home for the quote unquote feeble minded, not because she was feeble minded, but because she basically got in the way her mother wanted to get rid of her so she could get remarried.

And this happened all the time, and as she would end up spending her entire life in institutions, even though she could very well have survived as fine on her own in the outside world. When she was a teenager, she met a man named Henry Goddard who was a psychologist who was hired at her school. The violand training school, and he discovered intelligence testing in Europe, which was just a way of trying to decide whether children were sort of kind of had an average mental age for their age,

or were a little slow or little ahead. And he started testing the students and then got so excited by the results he was getting that he started to think that he could come up with a whole science of intelligence. And around this time he discovers genetics, which is very new at the time, and decides to go off and

find the families of his students. And what he does is he draws pedigrees for all his students, and he will mark, you know, people who lived fifty one hundred, one hundred and fifty years earlier as feeble minded, just from the stories that his field workers would hear. And then he would then use this as evidence that feeble mindedness was a simple genetic trait, maybe carried by one gene.

So he publishes this book called the Klikak Family, about his discovery, and you know, and this he and others used this as evidence for a really aggressive eugenics program because they feel like, well, there are so many feeble minded people and we have to stop them from having children. In order to save our country, and you can't institutionalize all of them. So Goddard lobbies very aggressively for state laws for sterilization. Tens of thousands of Americans were sterilized

as a reults of these laws. And in Nazi Germany, the Calakak family book was used as prime evidence for their own attempts to you know, reshape the human race, and not only did they do sterilization, but they went further to extermination, all based on this, this faulty line

of evidence. So I think that no matter what sort of scientific discoveries that are happening now one hundred years later, we have to look back and see just how easy it was for very very intelligent peop poem, for very you know, for the for very prominent scientists to leap to incredibly harmful, destructive ideas based on their idea that they had figured everything out when it comes to our redity.

So here we are now, and if people are saying like, oh, well, you know, it's easy, we will just change these genes and everything will be fine, I think we have to really question ourselves and ask are we falling prey to the same kind of arrogance and simplicity that previous generations have fallen prey to. And that's a really clear point.

A good point that you make in your book is about how much damage scientists and not to scientists, that all of us can do when the science is poorly interpreted, unethically applied. So I think that is an excellent point. But it's coming out fast. This genetic research using like do you know, wide association studies, some scientists tend to get extremely excited over it. Do you fear at all?

And I do? I personally do fear sometimes that we might get too excited over the methods sometimes and lose sight of the actual purpose, Like we get so excited about, Wow, we invented this new way where we can capture even more genes, you know, without actually looking at kind of a societal, bigger picture. But both are important to understand, right, Yeah.

And you know, as a science writer, I find it really interesting to go back one hundred years and look at sort of how science writers then would talk about genetics and talk about these claims about intelligence and genetics, and it really does, you know, it really does influence my work now as a journalist. You know, certain the new York Times. I'm reporting a lot on genetic studies on things like intelligence and educational attainment and things like that.

I think these are really important studies, but I also feel like I want to be helping to really set the public record straight in the sense that you know, it's really to magnificant. For example, that scientists are now starting to identify genes or the very first time they're up to I think they're up to a few hundred now that have a statistically very strong association with how people do on intelligence test scores. You know, they are

passing very rigorous statistical tests. But the catches that each one of those genes, you know, the variants might account for a tiny fraction of one i Q point. That's that's the paradox is to say, like, statistically speaking, this is this association is strong, and they're being replicated. So they're doing everything that you would you would want in good science, But you can't then leave out that final step of saying, well what does that add up to? And it doesn't add up to very much at all.

And so you know, to the idea that you could somehow, you know, get somebody's DNA and a baby's DNA and just predict their intelligence or some other part of their life related to intelligence, you know, in adulthood. You can't do that. I mean, it's just not possible, you know,

with what we understand about intelligence. And so so when I'm reporting on these things, I want to I am trying to strike that balance and not only between you know, showing how the science actually works, showing the actual you know, limits of the science, but also like to say, like, well take that next step and say like, well, what is that you know, what do we do with that information?

You know, So some people are actually claiming that we can create what they call precision education based on the student's genetics. Robert Pullman is big into that, right he is. He is. Yeah, but I've talked to a lot of people who are very skeptical of that and sort of feel like he's kind of kind of looking past the big picture of education, you know. I mean, we've got much bigger fish to fry in terms of at least states.

I mean, you know, like I don't want to even hear I don't think we should even be really talking that much about these issues until you know, like there are up to date textbooks in all schools like things like that. I mean, it's just like our schools have much bigger problems to deal with, much more urgent issues than trying to figure out whether precision education could work or not. Maybe I'm gonna play Devil's avocate for a

second in some sense. So we do know, there's some really interesting research showing that certain brain development patterns in childhood do predict things like dyslexia, some learning disabilities, and that if we sort of catch a risk for some of these things early, we can actually cause a better trajectory moving forward. So I just recently and edited a book on this sort of thing, on kids who are twice exceptional, who have a learning disability but also have

areas of intellectual potential. And so I guess one could argue, and I don't know about the genetical, but least it's more easy for me to wrap my head around like brain scans, you know, in a sense. But you know, if someone would make that argument, say that that could be informative information, what would you say, Well, it depends on what question you're trying to answer. You know, there are, unquestionably, you know, some genetic variations that are very clearly linked

to you know, intellectual developmental disability. You know, we could just talk about things like down syndrome. I mean, it's like you can see, like having that extra chromosome has a clear cut effect, among other things, on how a child will learn. I mean, there's there's no question about that.

And there may be some very important, you know, precise links between genes and certain kinds of learning disabilities or maybe even certain kinds of learning strengths that could emerge, you know, and it might have something to do, let's say, with you know, some very narrow part of the learning experience. The thing is with the tricky thing with with what we call quote unquote intelligence is that it reflects lots

of different ways of learning and solving problems. You know, it's basically it's almost like a there's a correlation between between things like memory and solving logic problems and so and so forth. And there's definitely something there. I mean, I think there's a huge amount of psychological literature to

show that there's quote unquote something there. But the factor yeah, yeah, I mean general intelligence or you know, they're you know, they're people are doing using different words for the sort of underlying factor, and you know, you can actually see that there are genes that have an influence on that, and so that does tell you that there's something there,

but it's so all encompassing that it's very hard. I would find it very hard to see how you could really get any sort of useful, targeted help by trying to look for look at these genes on this list, this growing list that are linked to what we call intelligence. Yeah, it's a good point. And modern day educational psychologists working

within my field, they emphasize the global IQ score. It's really about how to specific deficits in like a verbal processing or auditory processing, et cetera, how that can inform a custom tailored intervention. So my argument was not about, you know, the global IQ genes, but more about like more target specific things that could actually inform interventions. I could see that being used alongside A not used exclusively.

I think that would be a huge problem if we started, if we started to use IQ, or so we started to use our genetic information a as a sorting mechanism and B as you know, the exclusive information of saying, oh, well, you know what we don't it predicts more variants than

family homes. So therefore let's not care about family environment, and that would be catastrophic, right, yeah, I mean I I think the most interesting potential for this kind of research is not actually to try to use it on individuals, but actually to try to do more research on large groups of people, because you can, for example, test out

different kinds of ways of improving education. And if you can control for genes that are associated with intelligence or how long you stay in school, that gives you this extra tool, and that actually makes it possible for you to get really statistically meaningful results out of actually much smaller tests. You know, so if you want to say, okay, if we give families money, will that help their kids stay in school longer? That's an expensive question to answer.

But if you have the DNA of these families, you can actually then control for genes that you know already have an influence on how long people stay in school. It's a small influence, you know, genes seem to predict things like around ten and twenty percent of the variation and how long people stay school. That's small, that's not a crystal ball, but that's enough for you to get a sort of a leg up on these questions, and so I certainly that's where social scientists that I talked to,

that's where they get excited about these results. Yeah, and Paige Harden's r in some good stuff about that, you know, good good. So let's move on to mosquitoes. It's a less un comfortable topic to discuss, but equally as important. So genetically modified mosquitoes. How could this turn into a nightmare? Can you think of any anyway? None jumped to mind.

But that doesn't mean that it couldn't happen. You know, there are certainly our cases where we have done things in science that had unintended consequences, and certainly introducing genetically engineered organisms into the world wild is something that we need to do carefully if we do it at all. So in the book, I talk about using actually using crisper to genetically engineer mosquitos so that they will pass

down malaria proof genes to their offspring. And the idea is that once you do that, that's going to be it. I mean, you may not be able to undo that. So within a few years, all the mosquitos in an area may have these genes. So you know, you want to think very carefully before you set those mosquitoes lose.

On the other hand, you know, you also have to take bear in mind that you know, maybe you around half a million people die every year of malaria, and you know, while we've made a lot of progress with all sorts of different treatments, we haven't created a vaccine that makes people immune. And you know, the medic cations for malaria are not great. So there is an urgent need to do something. And so the question is is

Crisper going to be that? But you know, as you say, like, could you wreak havoc with this, well maybe, I mean, I don't know. I mean mosquitoes they're a part of their ecosystem, and if you tamper with their biology, are you going to alter how they interact with other species? Will that radiate out into unexpected changes? That's certainly something that you know, scientists are looking seriously at. It's just as possible as the havoc we can reach by trying

to alter our own DNA. You know, there's a whole bunch of people that would well, once there's technology advances to try to live forever, right, to try to like change the course of human evolution. So, yeah, all these things are really important to discuss, even if we're like so many years ahead. It's great that people like you. Again, the conversation started so similar topic, genetically modified crops. What

will this mean for us in the environment. Well, you know, this is really moving forward in a way that sort of fits in with, you know, the past decades of crop engineering, you know, basically saying trying to find ways to get crops to grow, to grow better, to grow

under different conditions, and so on. The advantage that Crisper has over some earlier methods is that you, for one thing, you can introduce particular mutations that you already have good reason to think are going to be effective, rather than say, blasting corn plants with X rays and just introducing less

of random mutations. Before now, the genetic engineering that people may be familiar with was really about sort of introducing DNA from one species to another, and crisper doesn't require that because you can, you know, make tweaks to the plant's own own DNA, So you may be able to have crops that maybe to grow under you know, drought conditions that probably we're going to be facing because of climate change. There's a lot of promise to using them

that way. You know, what I would hope would not happen is that companies would use Chris Bird to basically engineer crops to be resistant to pesticides. That would then lead to massive use of that particular pesticide, which can potentially have harm to the environment, and then you know, also eventually lead to resistance in the insects or the weeds that you're trying to kill, which then forces you to go to a different pesticide, which might be even

more harmful. If we get stuck on that sort of treadmill, that could be a problem. Thank you for explaining that. And another thing I found really extremely interesting ear book, like one of the one hundred things on the list our emerging research in the field of developmental biology and how the external environment can produce some quirky form of heredity.

Can you describe that? You talk about it in rats, but how they can learn to fear certain odors associated with a shock and that can be inherited by the offspring. Is that right? Yeah, So this is a part of a big area of research known as epigenetics, and you know, epigenetics has inspired a huge amount of fascination across the board. I mean, it's really interesting how when I give talks about heredity, when it's time for Q and A, lots

of people want to know about epigenetics. And so epigenetics basically means, the way I think about it, is the control that cells have over their genes to determine which genes actually do stuff and which are silent. And it's clear that you know, as we develop, our cells shut certain genes down pretty much permanently and allow other ones to be active. And that's you know, that's how we are able to produce you know, hundreds of different kinds

of tissues in our bodies just from one genome. And you know, when your skin cells divide, they make more skin. They don't suddenly turn into teeth or something. So it's not like epigenetics is some weird fringe idea. It's at the center of biology. But you know the fact is that also our environment can trigger epigenetic changes in us, you know, whether it's stress or some other kind of experience.

And so some people have said, well, is there any way for those changes to actually get passed down to the next generation. So if your genes undergo an epigenetic change in how they're running. Could your children inherit that change? So this would be a sort of a separate channel of heredity. And so there's this one very high profile

experiment that researchers did. They exposed male rats I believe, to a it's a harmless odor, and then would give them a shock and eventually they learned to associate the oder with the shock, and you could sort of measure their response. As soon as they smell the odor, they knew who something bad was coming. These male rats then made it. And then the hops, who you know, had only inherited, you know, their the genes and whatever else was in the sperm of those male rats, they seem

to have an odd response to that odor as well. Fascinating, but it hasn't been replicated. It's not like people have shown that this gets carried down through several generations. So there are actually a lot of scientists whore very skeptical that this is actually a real result at all. If it was, that would be really quite amazing. But you know, I think we have to be really cautious about embracing

these kinds of results. That being said, this kind of epigenetic heredity is real it's just not necessarily real in us or in rats. In plants, for example, plants to get attacked by insects and they can, you know, create a bunch of chemicals to ward them off. Their offspring are going to respond faster to chemical attacks than other plants would, and that gets carried down through generations, and so hypogenetic inheritance, this alternate way of inheriting things is

a real thing. One of my colleagues, who studied prodigies in depth, was really interested in a finding that a large proportion of his prodigies you'd find that somewhere like the great grandfather had a similar talent, you know, that seemed to kind of burst forth without too much practice in the young child, and that's never been explained, and it'd be interesting to see if this can help explain

that at all. Well, you know, I mean, I guess I'd be skeptical that this would go anywhere to explaining that, because you know, you'd have to ask, well, how was it that that was sort of carried down through the generations, and why didn't the intervening generations show it? And see how that happens with recessive genes. There's a very clear way that that can work, But no one's really come up with a good explanation for how epigenetics could work

in a similar way fair enough. So maybe an alternative possibility is just that the child seems to just have genes that facilitate that you're learning in that specific domean they just happen to get that package of genes from the gene pool. I mean, it's interesting to think about. It's all very interesting to think about, and you know, we were always looking to try to figure out how

children turn out the way they are. It's very tempting, though, to look at their ancestors and do a kind of pattern matching experiment, and you may just be seeing connections that really aren't there. That is just a random association. So let's move on to human chimeras, people whose bodies contain a multitude of genomes or just a different you know, genomes.

Can you describe that a little bit. Yeah, So we'd like to think that we inherit a genome that's a combination of DNA from our two parents, and there's just one genome and that's who we are. But the fact is that we can inherit different genomes. So some people are actually a combination of twins, where some of their cells come from one of the twins and some of them the cells come from the other. And this they mightn't even know they had a twin. The twin may

have died in the uterus before birth. It's also what's also remarkable is that people can actually pass their DNA to their mothers before they're born, and so mothers can actually become chimeras where FETO cells actually take root and their bodies, even in their brains and develop into neurons. So you know, a lot of us are in fact chimeras, and you know, it used to be thought it as like a bizarre freak of nature, but I'd say that a substantial fraction of humans are chimeras well. I didn't

know that till I read your book. So that's a really extraordinarily interesting. Let me ask you a little bit about your own personal experience, because I know that you've got your our own genome sequence, and you know, like Americans are obsessed with understand their ancestry and twenty three and me and stuff like, that's not what did you personally learn from sequencing your own DNA? And what do you think some of the limits of that knowledge are

at this point in time. I think that we have been waiting for this moment when we can look at our own DNA, look at our own genomes, and we've been anticipating this as a profound, almost mystical experience, and I think we've been enabled buy that by some of these companies that offer these services. I don't think that the experience is going to match up with those expectations for most people. Now, some people are going to discover that they have some mutations they should be concerned about.

You know, people who have a family history of any particular disease actually should just go to their doctor anyway and just try to get genetic testing that's more reliable in these director consumer things. But you know, for me getting my whole genome sequenced, you know, fortunately I didn't discover anything really scary in there, but it was an opportunity to learn how my genome, like thousands of other genomes, can be studied to understand really the history of our

whole species. You know, how our ancestors interbred with Neanderthals and other vanished kinds of people, how certain genes arose and became more common, even sometimes when these are genes that could be associated with disease. So I think that the best way to approach the possibility of looking at your own DNA is seeing it as a way not to learn about yourself in a kind of narcissistic way, but to learn about your species. Well that's a great point. And thank you so much for your time today and

for ranks such a beautiful and informative book. Oh My Pleasure. Thanks a lot for having me. It was good talking to you. Thanks for listening to the Psychology Podcast. I hope you enjoyed this episode. If you'd like to react in some way to something you heard, I encourage you to join in the discussion at the Psychology podcast dot com. That's the Psychology Podcast dot com. Also, please add a

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