Into the Impossible With Brian Keating - 90% of Ancient Humans Vanished. We Reconstructed Their History (ft. David Reich)

Episode Date: October 31, 2025

Get $50 off the annual plan at https://shortform.com/impossible The genetic differences we obsess over. The basis for nationalism, racism and tribal thinking emerged in just the last 70,000 years. David Reich is about to show us that the past is far stranger, more violent, and more interconnected than we could ever have imagined. 90% population replacements happened in just a few centuries in the blink of a cosmic eye. David and his team reconstructed human migration patterns and discovered ghost populations, entire civilizations that vanished without any archeological trace. These people built Stonehenge. These people crossed into the Americas. These people left no trace who they are, except for the code that lurks within each of us. KEY TAKEAWAYS 00:00 Ancient vs. Modern Populations 08:55 Ancient DNA Extraction Methods 11:55 Ancient DNA Extraction Process 16:10 "Decoding the Genetic Code" 24:41 "Neanderthals, Denisovans, Human Genomics" 31:05 "DNA Fragmentation Across Generations" 35:54 "Calibration, Culture, and Heritage" 39:34 Identity, Connection, and Myth Making 47:58 "Future Linguistic Biases and Bottlenecks" 50:44 Human Ancestry and DNA Depth 56:13 "Origins, Identity, and Genetic Stories" 01:02:39 "Dream Specimens and Cosmic Mysteries" 01:06:57 "Decoding Humanity's Collective Memory" 01:10:58 Ancient Origins and Human Connections - Get My NEW Book: Focus Like a Nobel Prize Winner: https://www.amazon.com/dp/B0FN8DH6SX?ref_=pe_93986420_775043100 Please join my mailing list here 👉 https://briankeating.com/yt to win a meteorite 💥 - Join this channel to get access to perks like monthly Office Hours: https://www.youtube.com/channel/UCmXH_moPhfkqCk6S3b9RWuw/join 📚 Get a copy of my books: Think Like a Nobel Prize Winner, with life changing interviews with 9 Nobel Prizewinners: https://a.co/d/03ezQFu My tell-all cosmic memoir Losing the Nobel Prize: http://amzn.to/2sa5UpA The first-ever audiobook from Galileo: Dialogue Concerning the Two Chief World Systems: Ptolemaic and Copernican https://a.co/d/iZPi9Un Watch my most popular videos:📺 Neil Turok https://www.youtube.com/watch?v=Dt5cFLN65fI Frank Wilczek https://youtu.be/3z8RqKMQHe0?sub_confirmation=1 Eric Weinstein vs. Stephen Wolfram https://www.youtube.com/watch?v=OI0AZ4Y4Ip4?sub_confirmation=1 Sir Roger Penrose: https://youtu.be/AMuqyAvX7Wo Sabine Hossenfelder: https://youtu.be/g00ilS6tBvs Avi Loeb: https://youtu.be/N9lUceHsLRw Follow me to ask questions of my guests: 🏄‍♂️ Twitter: https://twitter.com/DrBrianKeating 🔔 Subscribe https://www.youtube.com/DrBrianKeating?sub_confirmation=1 📝 Join my mailing list; just click here http://briankeating.com/list ✍️ Detailed Blog posts here: https://briankeating.com/blog 🎙️ Listen on audio-only platforms: https://briankeating.com/podcast #universe #podcast #briankeating #intotheimpossible #science #astronomy #cosmology #cosmicmicrowavebackground #intotheimpossible #briankeating #davidreich Learn more about your ad choices. Visit megaphone.fm/adchoices

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U.N. Must be 21 to enter. The genetic differences we obsess over. The basis for nationalism, racism, and tribal thinking emerged in just the last 70,000 years. David Reich is about to show us that the past is far stranger, more violent, and more interconnected than we could ever have imagined. 90% population replacements happened in just a few centuries, a blink of a cosmic eye. David and his team reconstructed human migration patterns and discovered ghost populations, entire civilizations that vanished without any archaeological trace. People built Stonehenge. These people crossed into the Americas. These people left no trace who they are, except for the code that lurks within each of us. What if I told you that everyone alive today,

all a billion of us, can trace their DNA back to a group so small they could fit in a modern football stadium? And that this near extinction event, 70,000 years ago, explains everything from why you get certain diseases to why humans are so similar genetically compared to other species. Soon we'll discuss with Harvard geneticist, David Reich, how he has discovered all these facts and many more from extracting DNA from bonds. They shouldn't even have any genetic material left in them, but still do. And he's performed almost miraculous work in the laboratory and in the field. But first, let me tell you about what's called a ghost population, an entire civilization that vanished without leaving a single archaeological trace. Yet David and his team have tracked genetic fingerprints, still hiding in your genome.

right now. David, I just came back from the UK. I was at many different sites there, including the British Museum, which has an awful lot of objects that we're going to talk about. But one place I went to that struck me very powerfully was Stonehenge. And sort of a clear indication of how civilizations, massive and mysterious as they are, they can collapse and not leave a remnant other than perhaps what they leave behind in their DNA. So let me ask you this question to open up. If ghost populations left no, trace in the landscape, how can we be sure that places like Stonehenge weren't built by cultures that disappeared entirely from the genetic record? Conversely, if you like, how many

stonehenges are we missing because their creators only left DNA, not stones? Yeah. So I think that thank you for having me on. It's a pleasure to be here. I think that one of the things that is a big open question in our understanding of our population, our human, of human populations and how things have changed in the past, is how people have moved to get to where they are today. And what's interesting in this context is with Asian DNA, with the ability to get DNA out of ancient human remains and see how people are related to each other and to people living today,

you can actually ask the question are people who lived in a particular place a long time ago, the same as the people who lived there today. And so what we found again and again in applying this technology to many places in the world is that people who lived in particular places in the past are not directly ancestral or contributed very little to people with today. That's what you call maybe a ghost population. So concretely in Great Britain, which is actually a place with a relatively simple history compared to more continental places, which have had many more population moving in or out,

Great Britain, there's been relatively smaller numbers of exchanges with the continent. But even there, there's very dramatic episodes of change. So if you take the case of Stonehenge, Stonehenge is built by the descendants of farmers who came to Britain about 6,000 years ago from the continent. Before that, there were hunter-gatherers from about 14,000 to 6,000 years ago, and before that there was a big block of ice on top of Great Britain. There was no one there. Before the Great Block of Ice, there were people there, but it was sort of cleared of people

during the last equation. So these farmers who came to Britain after 6,000 years ago, displacing the hunter gatherers, so that almost no but none of the country, the hunter gathers almost didn't contribute to the later population. They're the people who built the stone stonehenge. Fifteen hundred years later, the last big stones of stonehenge grow up. And then if you look at DNA from people who live there, just 200 years later, it's a completely different. It's a completely different group of people all over the outbreak of them.

It's at least a 90% population for turnover, possibly as high as 100%. It's a very dramatic change. And what seems that have happened is there was a stream of people coming from the continent that largely displaced people who were there before. So today, Stonehenge is a sort of cultural treasure in Britain. It's sort of seen as part of the heritage. But it's not built by people who are largely the ancestors, the people who live there today. And so let's get into that because what you've shown with your work and your colleagues in your lab and in the field is something that challenges how most people think about human identity.

The fact that was so striking to me, if I remember correctly, is that every person outside of Africa, whether they're in, you know, Tokyo, Stockholm or Sao Paulo shares ancestry from basically the same tiny founding tribe or population 70,000 years ago. And so before we get to the details, the nitty-gritty technical details that my audience love so much, I want to get to how you did this using ancient DNA. I want to explore the philosophical implication first and foremost. What does it mean for what we think about human diversity, for nationalism, for racial categorization, if we're all basically relatively recent by cosmological standards, descendants of the same tiny little tribe? Humans are pretty non-diverse compared to our relatives like chimpanzees. So the population structuring that exists amongst chimpanzees into different groups goes back

hundreds of thousands of years, whereas humans become relatively homogeneous amongst almost all living people today by maybe about 70,000 years ago. There's a few exceptions that go back a bit more, but basically by that time. And this is true comparing West Africans to most East Africans, to all done. non-Africans going back 50 to 70,000 years ago. So what seems to have happened is that there was a group that went through some kind of cultural development, I don't know if it's biological in particular, but that then might it to expand in dramatic ways, probably out of Africa and the Middle East, both within Africa

and outside of Africa, displacing the humans that were there before, maybe mixing with them a little bit. And that's where we all come from or where we nearly all come from living today. So all the changes that have accumulated across human populations, the great majority of them owe their origin to events that occurred during this. So I want to walk through the technological developments and how you fascinated me when I saw you for the first time at the Simon's Foundation in June. I attribute to Jim Simons, my late great mentor and I'm sure influence on you and many and many of our audience members as well. But I want you to walk us through because as this guest, who I'd never had on Carl Sagan,

this is him with a huge neck and his trademark professorial patches on his elbows, but had on his wife, his widow, Andrewian, and his daughter, Sasha Sagan. So I feel kind of close to him. But he said famously, extraordinary claims require extraordinary evidence. So here's what I find most intriguing. And I'm just a simple, humble experiment. mental cosmologist. How do we get actual DNA samples out of things that are essentially bones, and they almost look like they could be in a museum? And how do you use algorithms to turn these fragments that have been degraded, perhaps mishandled, or whatever, into detailed human migration map? So walk us through the technical details of how do you actually get DNA, which I think about

is coming from, you know, may foolishly or not vials like this, that I scoop up down at the beach. But how do you get DNA to begin with from an ancient, almost mineral substance? Sure. So this was something that 35, 40 years ago, a few people were working on tried to understand whether you could get DNA out of remains.

And what they were looking at initially were Egyptian mummies or museums, Stasimins, 100 years old, especially Svante Pabo, but also others. And it was very challenging. to get convincing DNA, there were a lot of false starts. There were a number of cases where it didn't yield anything, even though people thought that there were successes. Some people thought they got dinosaur DNA, and so on.

There was a breakthrough at some point where people started getting convincing DNA. One of these was a paper in 1997 by Svanti Papo and his team, which got DNA out of Neanderfell. So these are archaic humans who lived in Europe 50, 60, 70,000 years ago and more. and they got a sequence from the mitochondrial DNA, the part of the DNA that you get from your mother and she gets took her mother and occurs in thousands of copies per cell. And the way this works is you take a little bit of sample, so some milligrams of bone power or maybe a 40th of the weight of a paper clip, and in a clean room where the goal is to get

beneath the surface of this old remain, the part that may be not contaminated by archaeology, or by animals that might have touched it but might be more representative of the individual whose bone or two-fit was, you then take a little bit of this powder and then you remove the protein and the minerals and you extract DNA. So why is their DNA less there at all? When you extract from an Egyptian mummy, there's usually almost no DNA in it. And the big, lucky briggs seems to be that the biochemistry or the structure of bone contains, mineral content that serves as an excellent preserver of DNA. So the hydroxyapotide mineral content of bone seems to catch DNA and adhere it to its surface, to absorb it when cells

chatter upon an organism's death. And you have these fragmented bits of DNA that are stuck to the hydroxyapatite. And it's a much better preservation even than a natural sort of soft tissue And so the things that we have left from ancient individuals, the bones, the chief, actually also are often had DNA intact, so much so that, for example, for some cases, you can get DNA out when you can't even do a radiocarbon date. There's not enough carbon to preserve. And so this discovery that DNA was preserved meant that it was possible to go back in time to people who lived thousands, tens of thousands, or in some cases, even hundreds of thousands

of years ago and extract DNA. And then the other big development was the technological revolution in DNA sequencing that occurred in the late 2000s when it became possible to sequence absolutely vast numbers of little sequence fragments from DNA samples for about 100,000 or even a million times less than the cost to sequence DNA when the human dictator project was moving forward. So this was a transformative change, and it meant it was possible to take these millions, billions of highly fragmented bits of DNA that are canal of this bone and sequence it. What you get are little fragmented damaged sequences. Most of them are less than 30 DNA letters, bases long, but a handful of them are longer than 30 or 40 or 50 or 60 DNA letters long.

And that's long enough to reliably identify where the human genome or other organisms, genomes they come from. And that's what we do. So we apply this process that's evolved over time in a clean room where the goal is to protect the sample from the people analyzing it and who might contaminate in it with spathelized chemicals that maximize the amount of DNA that comes out, but protein and minerals, with sequencing technologies that maximize the amount of these very rare fragments that get into the sequencing reaction and then sequencing and sometimes enrichment for parts of the DNA that we're interested

in. So this combination of things allows us to get sometimes millions or tens of millions or hundreds of millions of DNA fragments from a person so much so that if you're looking at people who lived at the time of Stonehenge and you're looking at bones for more than half of those people were able to get genome scale data of a quality similar to what you get when you said your results to a direct consumer ancestry test. We analyzed the data, I can tell you a little bit about how you analyze the data, but what you're left with is tens or hundreds of millions of DNA fragments that are human in origin and you can tell are from the individual whose voting was.

And then you try to make sense of that in terms of how they relate to other people you have data from. Today's episode is sponsored by Shortform, the smartest way to keep up with the world's smartest ideas. Look, I'm a professor, podcaster, and parent, and I don't have hours to spare. When I needed to prepare for a guest like David Reich, the geneticist redefining what it means to be human, I started with their Chrome extension to instantly summarize Reich's papers on ancient DNA and human migration. I dove deep in the Shortform's full guide on his groundbreaking book, who we are and how we got here. For today's interview, I leaned on strong short-form summary of works connected to Reich's research like sapiens, the selfish gene, and guns, germs, and steel to see how genetics, archaeology, and evolution all intertwined.

I was on a deadline to release this episode the same week as book got published, so short-form was indispensable. I needed to make the connections fast, and they didn't disappoint. Reich's ideas connect with thinkers like Richard Dawkins, Jared Diamond, and Yuval Harari, helping me frame how ancient DNA rewrote human history. But it's not just books. Short form adds articles, podcasts, and even AI-generated summaries. I'll use it for research on AI hype cycles, for catching up on the latest astronomy papers, or yes, even sometimes for parenting questions, diving into their podcast and articles. It's become my daily driver, my curiosity companion, helping me to save hours and hours a week.

And it will for you too. You can try it for free. And if you go anyone, you'll get three extra months on me. Whether your curiosity has been sparked to explore our Rike's discoveries about our shared ancestors, You just want to dig into the new insights into genetics, evolution, and civilization, Shoreforms got you covered. Start your free trial plus three bonus months at Shoreform.com slash impossible or click the notes below. Now back to my conversation with David Reich. So they essentially were looking for echoes in the genome and then maybe supplementing that with artifacts of culture.

You know, soon we'll get to discuss creatures and cultures that are listed in the Torah. Tanakh in the ancient Hebrew Bible and what they might have been referring to, if that's some kind of echo in our in our cultural or mimonome. I don't know. I know I've talked to Richard Dawkins many times, but, but I don't think he talks about the, the memotype or the mimonome. He is, of course, known for the meme. But before we get there, I want to ask you about the algorithms themselves and how you do, you describe the laboratory kind of processing, but what's actually happening? I mean, I talked to Craig Ventner here last year, and he went into great detail about the Human Genome Project, but he basically said it would have been impossible without large-scale computing

advances and kind of Moore's Law. How much are you relying on algorithms? Do you rely on LLMs or any other kind of techniques, diffusion models? What kind of advanced algorithmic technologies are you using? You mentioned before we started with discussion by Nick Patterson and all. Can you talk about the algorithmic, mathematical, code-breaking analyses that you and your team members use. So the genome is basically a big code, and the activity we're engaged in as geneticists, especially historical geneticists, but also molecular geneticists, is to read the message. And so it's a cryptographic problem in some way. And there are all sorts of levels to this.

So once you have the DNA sequences, there is a bioinformatic problem, which is just processing the sequences. And that involves things like for, you might have a data set of 100 million sequences, each 40 bases long on average, and you want to know what species they come from and where in the DNA they come from. And so that involves performing a computation 100 million times where you compare to a database that is absolutely huge because it consists of all the sequence genomes of all the organisms that you know. and you want to place this sequence uniquely in this universe of possible sequence spaces that it could be aligned to. So that's an alignment problem, and there's very fast mathematical methodologies that will rapidly take a sequence and place it, even though the target is huge and even though the operation has to be repeated, pens or hundreds of millions of months. So technologies have been developed in the 2000s to do this

incredibly rapidly and on a scale that you can deal with billions, even trillions or sequences. And so we do this in our laboratory. We use compute clusters that have thousands of nodes that do these operations in parallel align the sequences. Once we have sequences aligned, Typically, our question is human-focused in our laboratory. So we'll only analyze the human sequences. We might sometimes analyze the human pathogen sequences if there are some. And we will then try to process the data to try to remove the errors or identify the errors or identify the contaminants. So we'll do various operations on the data to try to establish the authenticity of the data.

That's a whole other series of bioinformatics analyses. And then we'll create a representation of the sequences that we have that is, in some sense, clean for analysis. So one version of this might be, let's take a random sequence from our sequencing at every position in the genome we want to analyze and use that random sequence to represent with that person. That's one possible representation. There's other possible representations that perhaps extract more information, perhaps

stress and weaknesses relative to what it is. And so we might do that. So that's the bioinformatic process. You create a data set where the positions of the genome were analyzed in the who want to compare to other humans we've sequenced for the past and present. We can put them all on the same framework. Excellent. So keep in mind, I'm a simple experimental cosmologist.

And I know nothing about biology or genetics except for when I did dissections in my high school, you know, biology class the frog came back to life and then suffered. immensely. But why are mitochondria, and not, if I remember, Golgi bodies or some other substance in a cell? Why is that so much more powerful and effective at doing the reconstructive work that you and your colleagues do? So most of my work doesn't work on mitochondria at all. We sequence it all every time and we collect goaddea from the mitochondrial sequence. But most of my work does not focus on the mitochondrial DNA. Ancient DNA started with a mitochondrial DNA work because it occurs. It's so much higher concentration than anything else in the genome. So at the beginning of the age and DNA

revolution, it was magical to be able to even be able to get anything at all. And the techniques were so bad that people almost couldn't get anything at all. And in every cell, there's maybe about 2,000 mitochondrial genomes for every one nuclear genome. And so the copy number is about a thousand times higher. So if you're not getting almost anything at all, you have a much better a shot of covering any part of the mitochondrial genome. And so that was how it started. The other thing is that mitochondrial DNA is often quite diagnostic. So for example, we now know Neanderthal with Kay humans who lived in Western Eurasia up

to about 40,000 years ago. Their mitochondrial genomes are completely disjoint and different from the mitochondrial genomes of modern humans living today. So it's quite diagnostic of whether you're studying the Neanderthal or modern human, whether they have this unique Neanderthal sequence or model sequence. And so that was useful as well. Whereas for the rest of the genome, it's a more muddy picture. Typical places in the genome, I might be more closely related to a Neanderthal

and then equites in the genome that I have to you because we shall close. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals because we're built for what you're building fit for your ambition for citizens back we'll get into some of the difficulties you face in terms of biases calibration systematic errors but before we do that i want to do what you're never supposed to do which is to judge a book by its cover i even invented a jingle uh that will be playing right now we're going to judge a book by its cover hey book lovers we're judging books by the covers we know we're not supposed to do it better into the impossible there's nothing to it let's take a look and

David, do you have a copy of how we got here with you, or should I insert it in post-production? Okay. All right, great. So take us through the title, the subtitle, and the artwork, which I have the audiobook. The audiobook has different artwork, which I actually, I'm sorry to say, I prefer to that cover that you're showing now. Have you seen the audio cover that I'm talking about here? I'll call it up on screen. But I really love this artwork because, you know, it's a little.

It, here we go. This is the artwork that I read. I like it a little bit better, but it's kind of cool. So tell us, David, what's the origin of the title, subtitle, and cover it, art, please. Well, the origin of this, the, I forgot what the original proposed title was. When I originally set out to write this book, the subtitle, The Subtitle, Ancient DNA and the New Science of the Human Pass, was, I think, part of the original proposal.

And, and, and, but the who we are and how we got here was not. and a reader of the book, actually Skip Gates, when he read the book, he gave, he said, why don't we call this book who we are and how we got here? You use that language many times in the book. And, you know, it's not, it's a pretty good description of what the book is about. The book is about how we got to where we are today as a variable group of people around the world. And it's explaining this from the point of view of migrations and, you, of migrations and, you

movements of people through the lens of ancient demons. So why don't you consider calling it who we are in Africa? So I thought about it for a while, and then I eventually thought that's actually really a great film mission. So that's how the main title came about. Great. And then the artwork that I have has a DNA or a double helix, kind of digital staircase or something like that.

But that one's just a green and white cover. So it's like this. This is the, the artwork is done by Oliver Ruberi. And there's a few different ones. So yeah, show it. Here's one. So this is a, this one has a kind of very subtle picture of the dali skull. Yeah.

Which is a possible denise of him. One of these are caricaturates. And people did lots of different artwork, different languages that we translated into, with various variations or different ideas altogether about this idea. The original artwork was based on these lines, which are supposed to be suggestive or not some of the bonds of DNA and is done by this amazing artist

I got to work with Oliver Uverdi who did the work with me, collaborated with me and drew the images that are in the book, the black or moid images. Excellent. What's a difference between what a Neander-Tal is and a Denisovan? One is from Europe

and one is from the steps of Asia or what is the difference? How do we think about them? So, Neanderthals were known from the archaeological record and the skeletal record for since the 1850s. And in Europe, they were discovered in the Neander Valley in Germany for the first time and in many other places as well, eventually. And they were recognized as close relatives of humans, big brain, as tall as us and so on. There was no other known close relatives of modern humans until 2010, when the Denisovans were discovered. So what happened when Sante Pabo set out to sequence the genome of Neanderphals was everybody knew that it would be phenomenally

interesting to get a sequence from our closest relatives, and that if we could do this by sequencing DNA, we would be able to learn what has been specific to our lineage of hundreds of thousands of years since the split from Neanderville. Maybe we could learn what makes humans distinct from Neanderfels and, you know, of course, also chimpanzees. We learned that from sequencing the chimpanzee genes. And so that was the goal. And it was incredibly exciting to begin to get this data to try to analyze it and to learn about how the Neanderfills related to modern humans

and whether they had nature bred with people living outside of Africa as modern humans spread out of Africa from the least. That was all very exciting. But there were surprises in that work very strongly. But one of the things that was most surprising was that Sante Pabo got shared abound from a cave in Siberia by some Russian archaeologists and anthropologists, Anatolia Dior Vianco and colleagues from the Alta Mountains.

The Siberian was a finger bone from what was probably a little girl that was not classifiable as either in line. human or a Neanderphal and thought they were, was probably one of these two groups. But when Sante sequenced it, it turned out to be something completely different. So it was not the Neanderphal. It was not a modern human. In fact, modern humans and Neanderphals on the mitochondrial DNA are related within about three or four hundred thousand years. But this thing was a million years separated from minor. So it was an incredible stock, incredibly interesting, to be able to get the DNA

sequence from just a bone, without a whole skeleton attached to it, without artifacts, and and so on, and yet it was a something else entirely. So the history with the Neanderphals, we knew they were going to be interesting, and so these were fossils, and we were trying to get a genome out of them. But with the denis of them, we got a genome first. It was a high-quality genome,

and then we were looking for a skeletal record, cultural record remains to connect them, which actually just in the last year, it's beginning to accelerate it to find those connections. So the next topic I want to get into is subject that we usually gloss over, which is the presence of biases, not just talking about cultural or racial or any kind of biases like that are things we talk about in academia as nauseam, on ad nauseum, unfortunately. But I do want to talk about how you confront the biggest

sort of systematic errors. I always tell my students the most important thing is not the value you quote for the Hubble constant or something like that, but how you characterize your ignorance of that. And that ignorance component, the error bar, so to speak, has at least two maybe more different components. One is called systematic. And that has something to do with the system, the environment. In our case, the galaxy, if we're studying the Big Bang, we have to live in the fact that we live on a planet and in the galaxy. And there's all sorts of contaminants out there, as I know all too well. But what sorts of contaminants or biases systematic do you have to deal with?

And how do they compare to the statistical uncertainties that you have from just post-auntary? of experimental samples and evidentiary, you know, instantiations of these creatures individuals just by virtue of the fact there are at least 8 billion, you know, more of us now than there were back then these smaller populations. So what are the biggest challenges and how do you mitigate against them? Yeah, I've never thought about it in terms of the kind of physics framework or systematic and statistical error. We don't quote systematic errors in our fields, but we spread, actually, as critical physicists do. So I think,

we should. No. So one thing to realize, first of all, is that the statistics are not so bad for a lot of genetic measurements. Maybe they're often excellent. So the genome's a very big thing. So it's three billion DNA letters long. And within those three billion DNA letters, comparing any two people, there's about a difference every thousand DNA letters, bases. That's about three million and differences between any pair of people. And they're living on tens of thousands of essentially statistically independent segments that have moved through different genealogical paths connecting people around the world. So you basically have tens of thousands of independent replicates of this genealogical process

across the genome. And so if you can make an inference on, for example, a reconstructed genealogy connecting a whole bunch of samples you've sequenced and say, well, does this reconstructed genealogy, what kinds of population histories could it evolve under? You can then repeat that experiment tens of thousands of times and the data exists to do that. I'm not sure I explain that. Let me try another way. So another way to think about this is if you ask, how do I relate to you? You might think we all, well, maybe we're not going to be able to say very much because we're just one sample, one person each. But that's not true because you are not a single person. You're a multitude of people.

And the reason you're a multitude of people is you have two direct ancestors and four second-degree ancestors, grandparents, and eight third-degree ancestors, like great-grandparents. So it doubles going back every generation. So if you go back 10 generations, you have been on the order of 1,000 ancestors. If you go back 100 generations, you have on the order of a million ancestors, many of them will be actually the same because they'll be impingled ancestral trees. and so on. And your DNA also goes back in time in fragments into segments, not multiplicatively, but additively. So every generation, your DNA fragments maybe 40 times on the female side, 25 times on the male side, and into segments. And so you have about 70 additional fragmentations going back in time.

So if you go back 100, 10 generations, your genome will have fragmented into something like 70 times 10 or about 700 ancestral chunks to spread over about 1,000 people. And so very not so long ago in time, you're querying thousands, tens of thousands of independent ancestors, and you could independently study how each person's related to each other. And so that's why when you send your DNA to a direct consumer ancestry-thested company, like 23MB, and test yourself and see how you're related to other people, you can position your DNA with exquisite accuracy with respect to other people because you just have so much data to work with, so many independent replicates of the evolutionary process. So that's the miracle we have.

And when you sequence DNA from Asian human remains from meandertholes or people from Stonehenge, what you can do is similarly position their DNA, which we read out across much of the genome with respect to all the other data than we have. And what we do is we can learn with high accuracy how they're related to each other, even with a single sample. So that's what we do, and that's the statistical error. Then there's techniques that try to extract even more information

or less information, and there's trade-off between bias and amount of information you get. One thing that our research group has done a lot of has been to focus on methods that are robust through some of the biases and the types of methodologies we have. Yeah, can you say more about that? Does that have to do with the pseudo-happily alloyed or they have this, what you call it, the downsampling?

Exactly. So those are some of the issues. So, you know, I think a lot of these techniques we developed to analyze the Neanderphal genome and the Denisovic genome, which we were analyzing as part of our collaborative work with Sonti Pabos group. And what we wanted to do was build, techniques that could deal with really fragmented data that had various sorts of biases. And so we emphasize these methodology that would not be so affected by these biases.

And so, for example, one issue that happens is that we have uneven coverage across the genome. So some places we have data from, some places we don't. How do we deal with that? Some places we have lots of data from. So how do you represent every position in the genome? A tempting thing to do might be to do majority rule. Like take, if you have 15 sequences covering a particular position, let's take the majority type. But there's subtle biases related to that that actually are really terrible when you actually are tearing out these sensitive statistics.

Like, for example, if there's a bias toward when you align the DNA to the genome, it's going to, if you're looking at a position that's variable, some people in one type and some people have another type, that's where your information comes from, the variability. the type that aligns to the human genome reference sequence, the common that's been sequenced and that everybody uses for DNA alignments, it will align more easily. So if you're a variable person who has one copy of the variant from their mom and the other copy from her dad,

the version from, say, the mom that matches the reference sequence will align better. And so we'll always win in majority rule. So you'll have a reference bias that if you're not careful toward the majority variant. Is that the GRCHA? H-38. This is GRC-38.

That's one of the latest reference sequences. People are updating these to get better and better. There's recently been these end-to-ed DNA genome sequences that are probably even better than the human genome reference sequence and probably will eventually do. There's genome reference. People are now thinking about mapping to the variability itself explicitly rather than to a single reference to represent everybody. And these will help and solve some of these issues.

But one of them is this reference bias that you mentioned. Another issue is that the DNA fragments from ancient humans have errors of them. They've been sitting under the ground. The ends of them have been fraying of the sequences. They're full of cytosines that get misread of thymines. How do you deal with those errors? We need to understand the biochemical process in order to do that. So we know thymines that we observe can often actually be relieved cytosines.

We know where these errors are most likely to occur as a function at the distance from the end of the sequence. And so our analysis is to be aware of these types of biases and correct for them explicitly. It's peak pollination season and my business is scaling fast. To keep the nectar flowing, I need a phone plan with top priority data speeds. That's why I chose GoogleFi wireless. My connections stay strong even when the hive is buzzing. Plus, unlimited plants started $35 a month. Now that's a deal.

That doesn't stay. Explore GoogleFi Wireless plans today. Plus taxes and government fees. GoogleFi Wireless is not subject to data traffic deprioritization during times of high network usage. So I'm going to ask you later about ways to calibrate using cultural evidence. In other words, language or cave paintings and things like that as a way of kind of establishing a baseline reference to get rid of the systematic errors. You need to calibrate. It's effectively dedicating a whole new experiment to doing something that's not parallel to what you want to.

do from the beginning. But first, because we both share a common heritage in that we were both Orthodox Jews at one point in your life, I don't know if you still are, you know, or at least predisposed to Orthodox Judaism, I know for me, I kind of felt like, you know, Genesis 1-1 was a career, you know, kind of a counselor arc that I started out on to become a cosmologist. But there's an awful lot of interesting, you know, entities that exist in the Torah. in the Old Testament, for those that aren't, you know, we're not going to proselytize here that's forbidden by us, but for us by our religion. But I do want to talk about some of these things that seem to appear in many cultural instantiations, but in particular in Judaism and in the

Old Testament, which the Christian Bible also echoes as well. And I'm wondering if, you know, you were maybe influence as a kid too on these strange creatures and so forth that appear and maybe even the Torah itself as a cultural artifact that can supplement or complement the DNA evidence that we have going back, you know, 3,000 years or so. So, first of all, in the Torah, in Genesis, there are these creatures like the Nethalim. These are giants born of unions between humans and some celestial creature. You know, if we're on Joe Rogan, he would ask you about aliens. I'm not going to do that.

But David, what did you make of this as a kid? Did it have any influence on you? And what, if anything, can we learn from at least the memetic kind of propagation of these ideas that are found in many different cultures, but specifically the one I know best is in Judaism? I think the thing that I've taken away most strongly from, like, my Jewish background, which has been a hugely strong influence for me, has really been the very strong sense that Jews are not the center of the world. So I think a lot of, you know, it's a mind.

You know, it's like strangers living in strange lands. It's a group that's been largely in diaspora for much of its history, at least for the last 2,000 years. You know, now there's the state of Israel, but still many people live amongst as minorities. And you're constantly aware of the variation of the world around you and difference amongst people. And you know how small you are, right? because the world around you is so much bigger.

And I think that's also a theme of the Torah in many ways, which is like trying to make sense of your people's place in the world. So, you know, there is this question that I think we all face in one form or another. And in my particular Jewish tradition, I guess our tradition, there is a engagement with this problem, which is how do you relate to the world around you? and how did you get to where you are today? And you need to tell a story to understand that question. And you need to tell a story, and maybe as a cosmologist,

you also have this issue, which is how to understand the relationship between the tiny speck that we're in, right? The species on this minor planet and this, you know, medium solar system of the edge of a galaxy, which is one of hundreds of billions, like, you know, how do you comprehend all of this, right? And how you embrace this.

And, you know, there's a similarly, you know, challenging issue about how to connect yourself to a species that has 8 billion people in the world that's moved all around. And how can you get a sense of meaning in terms of your connection to all of that? So I think that being a minority living amongst majorities is a challenge in that way because it really makes you constantly contend with issues of difference and issues of being a minority and issues about not being the center of the world. It's just very much in your face if you're a Jewish person, but that's the face. And so for me, that's been important. The particular stories that people tell

about, you know, the invention of the past that people make about a creation story or the legends, I think that people are trying to fill it. For me, that has been myth-making, mostly. People trying to fill in details about what's incomprehensible history. You see this in all sorts of mythologies. And I think that in the deep past, or in the past when some of these documents were composed, the world was so overwhelming in science and understanding of the world was so poor that people really had to make up these stories to, in order to get to,

to sort of begin to make sense of the world. I think we're a different one. Your work on genetic drift and ghost populations, it just seems to have this echo. You know, for example, the epic of Gilgamesh has a flood story in it. It has a hero story in it, not unlike the Noah character, except there's a different moral implication from the Noah's story

than in the epic of Gilgamesh, where I think the gods wanted to have relations with Gilgamesh. But here, in this context, I wonder, you know, I believe in your talk at the Simon's Foundation, you referenced there were flood events and things like that. And maybe this was not only a case of, you know, trying to fill in the missing blanks in a low information environment, as you just mentioned and with which I agree. But maybe it was also documenting a common event, you know, in other words, this event of a flood could have happened and in different instances or could it have? I mean, you're the expert. So could there be this genetic drift that kind of aligns parallel with a cultural memory drift that causes these themes to show up in many different cultures, sometimes separated by large distance?

I think absolutely. I think that there's quite a lot of cultural evidence that survives from the past. One of them is one of the types of cultural evidence is our mythology. So stories of the flood will be. a mythological or a storytelling memory. And there are stories that are shared across cultures around the world that are clearly the same over thousands of years. For example, Indo-European cultures have some common seams like twins and so on that are clearly from populations that had these aspects in their religious or their worldview 5,000 years ago. And so maybe these are recollections of traumatic events that occurred, you know, either broadly in the world or specifically in the history of these groups of people

who are ancestral, culturally, or genetically, to the people, you know, who have their heritage today. There's all sorts of cultural evidence that exist from the past, and of course, genetic evidence. So genetic is one sort of evidence that exists from past. he inherits genomes from people who lived 5,000, 10,000, 20,000, 100,000 years ago, and that's the data that's being analyzed here. But in the same way, there's toolmaking styles and ceramic styles and mythologies and very much languages and how they're related to each other. And even though there's not writing from many of these places and many of these types,

these other types of evidence can be used to reconstruct who's most closely related to do and contain within them memories of certain things. Like, for example, the languages that we speak, you could tell, for example, in the parent languages of Indo-European that there are certain fair words where, for example, wheels and horses that are common in many of these languages, despite being spread over a vast area, and it tells you that probably the ancestral population was no new of these things, wheels and horses, but the languages for wheat are diverse, a variable. So maybe these populations shared a common linguistic ancestor after the, you know, after the agricultural extent.

And I think of it sort of as a memetic fossil record, some kind of a stable substrate that can allow us to track evolution of fear of belief of cosmologies. You know, we're not the first generation to have a big bang or to have a cyclical universe. I mean, we think of ourselves is so innovative, but, you know, there's Egyptian in the Book of the Dead writings about a cyclic cosmology that's now coming back in vogue. So I wonder, you know, how far back can we go with the kind of cultural mimatae perf, you know, whatever you want to call it, the memetic fossil record, K paintings, let's go as far back as you can go in a way that it kind of bolsters or not bolsters, but allows you to put a superstructure onto the DNA record. In other words, can we use the ancient

cultural artifacts to validate or disconfirm some of your hypotheses about population dynamics and an exam? I think that the strongest one that we use most often is often a foil and a hypothesis generator for what we do is the evidence from language. So there's about 7,000 spoken languages or recorded languages around the world. And languages become mutually unconnectable on a timescale of about 10,000 years. And they evolve a little bit like genes. They don't hybridize every generation the way that she's do, like in order to reproduce genomes have to mix with another genome. And so you have mixing that's enforced, whereas language doesn't mix in that way. There's usually a dominant language that's adopted, and you don't have a hybridized language,

although there are some borrowings. And so what you can do is you can use the languages to identify which languages are most closely related to which. That's the activity that historical linguists are engaged in. and to try to trace the relationships amongst those languages, and that will suggest to you that there might be a common ancestral population that once spoke the parent language and moved around and might have limped somewhere. So with this, we have all sorts of hypotheses we can test.

So, for example, the language we're speaking, which is a Germanic language, English is a Germanic language, with some bar of Latin words from French mostly, which falls within the Indo-European large. language system. I've done a lot of work around that and trying to understand how Indo-European language expansions are trapped by movements and genes. There are questions all over the world like this, the Austronesian languages, which are

spoken by people who, the first people of the Pacific and Madagascar and Indonesia. This expansion happens after 5,000 years ago, probably from Taiwan, and the exact details of that expansion are mirrored in the genetics. the expansion of Nodunay languages, these are languages like Apache and Navajo, are also marked by genetic uniqueness and distinctiveness amongst people from those types of backgrounds. And people who are Maya, for example, have a genetic impact from the South that dates to 4,000 or 5,000 years ago.

That seems related to potentially the spread of maize cat culture from the South and words in some languages that are at the boundary of Maya, Nipchitian languages, and so on. So again and again, this is a very rich seam of information for comparison to the genetic record. And we could ask questions like, does the genetics match the language? Or the answer is very much, yes. In other places, the answer is very much.

No. And so it's sort of an exciting kind of foil for the genetic. You just mentioned something really fascinating, which I didn't realize, but it It uptales to a question that I wanted to ask towards the end, but I'll ask it now. This noting that you made just a few minutes ago about the half-life of languages, or maybe it's the full life of languages, about 10,000 years. And at that point, it seems that the signal-to-noise ratio just goes to zero, and we lose the ability to track linguistic evidence.

I want you to consider 10,000 years from now, you know, David Reich's, what, 10,000, you know, great-grandson or whatever, granddaughter. and they're trying to reconstruct our era's cultural and cognitive DNA. What kind of ghost effects, biases will LLMs present to them? It seems to me we've invented a new, perhaps, bottleneck in our genetic evolution to track parallel with language. What are going to be the effects? Future David Reich, many years from now, looking back 10,000 years in the past, what will he, she, you know, your distant relative, if we survive, hopefully, what will they face in terms of

of contaminations or bottlenecks due to this a Cambrian-like explosion of language and the melding of silicon with squishy, wet, gray, or pink matter. That's a fascinating thing to think about. You mentioned the question. I'm sure about whether we survive very long. That's a good question.

So I think that there must be some massive cross-fertilization of languages that's now happening to these elements. And as people begin to use them in their writing, it must be very break all sorts of rules that used to kind of govern the way languages evolve.

I think that is probably already happening to a pretty extreme way even before in the last hundreds of years as people encountered other groups of people and so on and colonial anguishings began to sputter out. But, you know, what we have going for us is there's all sorts of written records now. They will probably, at least in some copies survive sometime. And I

can't we will at least be able to look at what we have to count trips of before everything. It's sort of scrambled this. You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton.

Welcome to your ocean front room. Just steps from the water. The Hilton sale is on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton, for the stay. In the book, you bring up this neologism, as your friend in mine, Stephen Pinker might call it portmanteau.

He loves to drop that on me all the time. You describe a black hole in our genes, a period from 5 million years ago where mitochondrial and Y-chromosome lineage is go dark. making it very difficult or impossible to resolve our genetic relationship to other primates. So what is the current frontier in breaking through that event horizon? Is it possible, or it will it be like the singularity that we cannot penetrate through in cosmology? Such a great question because there's been movement on that topic just recently. So just to explain the idea a little bit more.

So if you look at human variation, the time period we get information about is the one that is is spanned by the gap since we all show common ancestors. So if you look at any particular place in the DNA, you can ask the question, how far back do we all share a common ancestor at this position in the DNA? And for humans, it's typically like two or three million years in general everybody shares a common ancestor at any position.

For your brother or sister, you might share a common ancestor a generation ago in some places in your DNA, but for the average, it's two or three million years for everybody. There are places where it goes much shall work, like mitochondrial DNA-MY chromosome where it's about 150,000 years, and there are places where it goes deeper. And if you're trying to look at history, like, for example, a small founder of them, like the one you mentioned earlier, where some very small number of people give rise to large numbers of people today, the way that you'll get information about that is by the ancestors that you have collapsing to a single person at that time. So let's say there was a founder event of four or five million years ago. You won't see that because everybody will descend from a single ancestor three million years ago,

and we won't get any information about that time with collapses of lineages. The frontier here is that as DNA sequences have gotten better and higher quality, we can actually look at the small fraction of the genome that actually goes deeper. And there's a paper that's a pre-print that's circulating right now by Trevor Simons and Tripswick, Trevor Couss, and Richard Gerben and colleagues, that looks at these higher-quality genomes and tries to reconstruct population size change over time and finds that about 1% of our DNA

goes back at least to about 5 million years ago, and maybe 0.1% goes back at least to 10 million. And that that means that we can get information over that time period from DNA sequence variation in modern humans. It's only a percent. it's only 0.1%, but with high-quality enough data, we can reconstruct something about the population size changes. And with doing this, what they've discovered

is a period of large population size or substructure in the time period around 5 to 6 to 7 to 8 million years ago. And other lines of evidence based on comparison of human and chimpanzee and gorilla sequences also indicates, this is, I actually was heavily involved in this in 2006, that the period of human and chimpanzee and gorilla separating was also a period of high diversity, like extreme diversity.

And it's telling you about this very consequential period of time when these lineages is fragmented. And what it's telling you is that the population was extremely diverse and, in my opinion, probably highly substructured. And you can actually see that off patterns of variation today because of the improvement of quality of data compared to even when I wrote my book. You talk about even people in your own family and Israel, perhaps,

that were opposed to, say, some of the reconstruction from bones that discovered in Israel and other kind of cultural and so forth. We here in Southern California deal all the time with the fact that the Kumayay Indians occupied the territory that we are now on and UCSD, and they go back, you know, 10,000 years or something like that. Some of the oldest North American, you know, homo sapiens, as far as I know, that's what I remember. But what can we learn about this, you know, kind of with being respectful to the populations that existed and noting their distrust of European ancestry and the tendency that you mentioned in the book for people to talk about coming out of Africa? I mean, there's a book by that name, right, or a movie by the name. And that cult concept that sort of gives a teleology that the whole point was to get out of Africa and then establish, you know, European and North American later on. and then Far East Asia. So what are some of the sensitivities

and what have you learned and how big a problem is that now for your field, the genetic archaeology and linguistics? So that's a big question. And I think the first thing to say is that it's a case-by-case issue. So there is not a single framework

for thinking about how genetic analysis interacts with people's sense of themselves and how that may or may not interact with the United States. So what applies in North America is profoundly very different from what applies in, for example, East Africa and is different yet again for what happens in Mexico or Peru, and what, again, very different from what happens in Siberia and also different again from what happens in Europe or India. So in some places the history is such, for example, in the Americas where prior to 15,000 years or so ago,

the archaeological record makes it very clear that there's very few people or no people living there at all. And so there's really a sharp break between a period of time when there's no people and there's people, and then there's another sharp break about 500 years ago when Europeans and Africans come to the America. So there's a sharp break between who was there before and who was there. And so in many parts of the America, the idea of the people who were there first makes a lot more sense than it does in parts of Africa or Eurasia where there's just a succession of people over time, over a time span, not of 15,000 years ago, but 1.5 million years of human history, where there's just layer after layer of people moving back and forth and the idea of indigenousity and who is there first makes much, much less sense. I think that one of the things that's interesting about genetic analysis is that it tends to challenge almost everybody's understanding of who they are. So almost every story people reconstruct about themselves is wrong when you actually look at it and examine it with data that allows you to understand how people living in a place today relate to people in the past and the percentages of their ancestors who come from the world. And so an interesting question comes about, like, how do you have a conversation about people's origin stories or stories about some relationships to other people, maybe mismatch in the reconstruction you get from genetic data?

Maybe one possible answer to that is that the biological answer is not necessarily one that you should privilege more than people's storytelling or people's mythology about themselves. there it's not one's better than the other, it's just a different category of thing. Maybe another answer is that genetics often works to explode prejudice and explode and challenge beliefs that have been used to discriminate and so on. And that's in some ways been my experience and often cuts against people's presupposed bias. So you mentioned in the book, of course, that in our sub-component of the genome, you know, you mentioned before how small Jews are. It's true we're 0.2% of the world's population. But that doesn't stop us from having a name for the 99.8%. We call them Goyim, which just means nations.

It doesn't, it's not an insult. But, you know, where Israel is described as a Goya as well. But it's funny that we have a name, you know, it would be like NBA players, you know, having a name, you know, for all. all non-NBA players or, you know, dogs having a name for non-dog animals. Oh, really? Oh, I didn't know that. That's what they call it. Oh, really?

I mean, it's foreign or non-Greek. Wow. Okay, great. Well, I mean, you've also made the case that in our subgroup, you know, genetic Ashkenazi Jews, that we had a propensity possibly due to arranged marriages, which lead to some degree of interbreeding, I suppose, for Tasex disease, one example. And you mentioned also in India that the caste system also kind of enforces, you know, some maybe arrange marriages or something like that, but that they're less sort of open to the idea of genetic testing, perhaps, and even gene therapy is based on genetic lineage like we do before we get married, you know, at least to other Jews, we typically will take a TASX test if we're Ashkenazi. or if you're Sephardic, you know, nobody's perfect, but, you know, the Sephardian don't have to do that as far as I understand.

So that's good for that. But what other kinds of benefits could gene testing and counseling maybe do for cultures? And what are some of the benefits that we would like, that you most like to communicate to other cultural and population, you know, very large cultural and population groups? what would be the biggest impact sort of in the utilitarian sense to improve the flourishing of humankind? Sure. So there are quite a lot of groups in the world and very large numbers of people who are part of the dogamous groups, groups that like Oskinelli dues on the order of 1,000 or 500 or 2,000 years ago, descend from a relatively small number of founders who then had lots of kids and their kids have lots of kids and their kids have lost kids until there's hundreds of thousands or millions or tens of millions of descendants today. And when this happens, a slight, you know, bad mutations that are perfectly innocuous in one copy, but are deadly in two copies, get jacked up in frequency as a result of the founder event because of one of the relatively small number of founders is ancestral to many people living today.

And there's many individuals who are getting two copies, one from their mother, one from their father, and they come together, and they're lethal, like Tay Sachs, for example, or Gasease disease, or various forms of cystic fibrosis and disodomnomia. other diseases. And so in the Jewish community, in some communities in the West, there's been intensive study of the diseases that specifically affect these communities. So in Afghanaazi Jews, there's identification of this set of genetic changes that cause high risk, particularly in this community, and people are tested for them during pregnancy. And actually, in the context of arranged marriages, what is common in some of these communities, even before people are introduced to each other,

so they're not introduced in their boat characters, where they're considered incompatible. And in the Orthodox communities that practice arranged marriage, this is headed off many, many thousands, if not tens of thousands, of cases of diseases like they say. So Jews are just one such group. There are all sorts of groups like this in the world. There are probably thousands of them, we now know, in India,

with many, many more people than there are Jews, Afkanasi Jews. And in each of these, there is certain to be a set of diseases that occur at particularly high risk in these populations, and it's very easy to reconstruct a panel. And also in some of these communities, there's a range marriage. So that same sort of intervention is that done in Jewish communities, both secular and non-secular, in Finnish communities, and Sardinian communities, and Abish communities, and Hutteright communities in the West, Sardinian communities, that's entirely doable in many of these other communities in the world. And with modern technology, it's actually very cheap to imagine building these panels.

So that's an intervention that could probably save, for example, in India, 100,000 for next year. Very cheaply. Oh, that would be tremendous. When I asked your former colleague, Bob Kirshner at Harvard, what gift from Hashem, what gift from God he would most like to crack, say, the Hubble tension, which is the discrepancy between early and late-time measurements of the Hubble constant, at the expansion rate of the universe, which is the most important number in cosmology, because it determines the age and the future evolution as well of the cosmos. He said, give me a supernova at Redshift 10.

And the universe was an infant baby. Really, for various biases and reasons, we can't see supernova so far away. But that one supernova at the extremity universe would tell us a lot about the cosmological model we live in. I want to ask you a parallel question to sort of let your dreams and your hopes and aspirational, operations run wild to get the high precision that your field could use to anchor it. So in ancient DNA, if God or Mother Nature, wherever you like, gave you one perfectly preserved specimen, complete genome, exact carbon dating, and a full cultural context, artifacts, languages, tools, even its mythology, what point in history would you choose for this specimen to arise from and what

grand mystery would you hope it could resolve or make more precise? I only have one wish. You only gave me one wish, so I won't get three wishes or ten wishes. But probably the answer has got to be something like early homo erectus 1.8 million years ago in Africa or in Georgia or something like this to get a high-quality genome sequence. And because that is this key time period after which our species rapidly, our brain stops getting bigger, our teeth get starting smaller, we start using tools, that's the moment. Okay, David, as we wrap up, I've got two final questions, big picture thinking as you're

so prone to do so eloquently. your work in this book and in your work since then and even before shows that we carry these fragments of a Neanderthal DNA, at least in our genomes, and echoes of encounters that they had tens of thousands of years ago. I guess the question I have is, do you think that these archaic genetic tracers still shape who we are in a direct sense, maybe even in a daily sense, not just biologically, but in terms of disease or immunity, but emotionally, cognitively, intellectually, even spiritually. You made the point that we probably recognized Neanderthal on the tea, you know, up there in Boston, but, you know, it wouldn't look so crazy. I mean, I'd probably like to have one on my men's league

softball team, and he might help me out, help our team, you know, be at its losing streak. But what do they tell us? What do we carry with them on a daily basis, perhaps? So if you're a non-African person today, you care about 2% of your DNA comes from a person who was in Neanderphal 70,000 years ago. It was actually carried in a Neanderfell, someone who lived in Western Paysa, and not in someone who lived in Africa's Africa. And it's probably slightly underrepresented in terms of its contribution to genes that matter. But on the other hand, they were quite different, and so it's overrepresented in terms of the amount of variation it explains. And these two percent of the amount of variation, it explains. And these two percent of

our DNA that comes from Neanderphals, it does a lot. So we know specific changes that, for example, in Tibetans allow people to be adapted to very high altitude. Those are from Denisovans. There's multiple aminological changes or cognition changes that come from Neanderphals and have risen to substantial frequency if people live in today. And so these changes, these bits of DNA, they were living with them, if you're a not African person. They've been, used by the organism to adapt to the environments people live in. They haven't been removed fully by natural selection. And so this is a really profound aspect of our biology.

Well, I want to finish with one final question, which really reveals kind of my journey with your work since meeting you, you know, or not, didn't have the courage to go up and talk to you and say hi to you in person, but I became so captivated afterwards. I couldn't resist getting in contact with you and reading your book. And that's kind of the way the lens has shifted and how I look at you. I originally kind of thought of you as a, as a, you know, CSI, you know, Neander Valley or, you know, some, some sort of a forensic scientist or detective or maybe a DNA archaeologist like, you know, Indiana Jones or something. But I now kind of see you as almost like a forensic psychologist, sort of decoding our collective memory, our collective migrations, maybe even our traumas as a sense. species. Do you ever feel like that? How do you view how your career as art since the late 90s, you know, and your PhD work and the 90s? And then up until today, how is your arc evolved?

And how do you see your profession? Is it truly still in the laboratory forensics and in the field? Or is it deeper probing our collective memory as a species? Wow, that's a fascinating question. I think the simpler answer to that question is that the field is growing up rapidly. And when I studied working, collaborating with Svante Pavo, for example, along with other people. It was really a cottage industry. There was amazing work going on in Svante's lab and a few other labs. And we were getting this absolutely amazing data.

It wasn't even a field. It was just a kind of endeavor. And now it's a field. There's hundreds and hundreds of people working on it. There's laboratories all over the world. Engage in this activity. There's amazing graduate students and postdoctoral scientists. to new faculty doing these different activities,

and people are being integrated into archaeology and anthropology departments and into history departments even and, of course, into biology departments, and it's becoming a mainstream field where any self-respecting university should have a specialist in ancient DNA in order to have access to this rich theme of information about the past. And the questions that are being asked are increasingly precise. wise ones. One's about, for example, this cemetery that's dug up under a burial caird in Great Britain from 5,700 years ago, these bodies are laid out in a particular position relative to the tomb that people think might mean something. How are they related to each

other biologically? Who's the mother of who? Who's the sister of who? You know, are these people not related to other people? Do they have particular diseases that you can reconstruct from the DNA, we can do these types of analyses easily because the cost of sequencing a working genome was now hundreds of dollars per individual, and it works almost every time for this type. So that's one aspect of it, but you asked about me and what I'm doing, and I think that what I'm doing and is really I want to support this professionalization of this field and this integration of this field into the armamentarium of ways of looking at the past. But I think that I, for me, like to hold in my mind the picture of how we're all related

to each other broadly and sort of interested in that big picture and holding in mind the richness of that picture all at once. And I think this kind of map-making enterprise, it's almost like a naturalist's interest in the world. It's an attempt to try to hold it all in one's head. how, you know, me myself, you know, you, other people one meets relate to each other, you know, how can we think about this sort of scheme of connections in some kind of meaningful way that allows us to understand our place in the human universe and also connect it to the

vastness around us? Yeah, maybe there is no line between the ideas that have traced back our distant, you know, tend to the fourth relatives and even farther back. David Reich author of who we are and how we got here. And just a fascinating true Renaissance man intellect. And I just very much enjoy your mind. And I do hope we get to meet again. And I'll have the courage to come up to you. And I'll give you an ancient fragment of the early solar system.

And I see it. There's a meteorite from 4.5 billion years ago. Or you can go across the street to Avi Loeb's lab and our office. And he'll give you maybe some from an alien space show. We'll talk about that next time, David. Thank you, David. Thank you so much. If you found David Wright's work on ancient DNA fascinating,

you'll absolutely want to watch my conversation with George Church, David's colleague at Harvard. We explored the cutting edge of synthetic biology and de-extinction, literally bringing back woolly mammoths, and even Neanderthals. George showed us how we're moving from reading ancient genomes to writing new ones, engineering life itself, and potentially resurrecting the extinct relatives whose DNA we still carry. Check out that episode.

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