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David Reich

lines on the record: 144
first: 2026-05-08
most recent: 2026-05-08
sittings or episodes: 1
sources: podcast

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“Industrialize the process so that there were many hundreds or even thousands per year. And so just in our laboratory, we've been generating genome scale data from more than 5,000 individuals per year. I know this is true also of several other laboratories in the world now. And this huge jump in data, this sort of semi-exponential or even super exponential jump in some cases, has made it possible to ask and answer questions. So we're only on the order of 10 genome sequences from humans in 2010. This year it was passed more than 20,000 reported sequences. So there's several orders of magnitude increase. And the questions we were able to ask in 2014 are just not the same as the ones we can ask today.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Mostly microbial, so it's from bacteria and fungi that colonize a person's body after they die, depending on how they die, there'll be more or less of these bacteria and fungi. And so when you typically sequence DNA from a person, it'll just be full of microbial sequence. Sometimes the microbial sequence is very interesting, so it might be pathogens that a person died of. So there's, for example, amazing work about different plagues of malaria and black death and hepatitis B and so on that have been obtained from the sequences of these pathogens in people's teeth in other parts of their body when they died. But we're focusing here on the human DNA. So what we did is we, this changed the amount of data that was possible to produce from tens per year to hundreds per year. And then we further roboticized.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“And so, what we did is we had this artificially synthesized set of DNA fragments that we washed our ancient sample over, and it bound the parts of the DNA that we targeted. And the resulting sequence that we generated was very enriched for the parts of the genome that were informative about history. And even though only 10% or 1% of the DNA was human, it ended up that a very large fraction was from the parts of the genome that we were interested in. And it became economically efficient to do it.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“All the time. And so we took these samples and washed them over a artificially synthesized set of short DNA fragments that targeted positions of the DNA that we were interested in analyzing. So this is more than a million positions that are highly variable in people. And we picked many of these to be biologically interesting. We had a whole set of known biological targets that affected traits in genome-wide association studies, which is the way that people look to see if there's particular genetic variants in modern people that have particular impacts and phenotypes and traits.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So there's been a whole series of improvements. I think that the big ones have been the huge drop in sequencing cost, which made it possible to generate ancient DNA in the first place. So the drop in cost has been a millionfold since the late 2000s, and another maybe one to two orders of magnitude from 2010 to today. So that's one big change. Another change has been in solution enrichment. So it's been this way of taking a sample that has very small percentages of human DNA, but then suddenly creating a process that will mean that the great majority of the sequence is that one's analyzing will be useful for analyses. And so the approach that we used was we took the DNA samples that we had, most of which were very low percentages of human DNA, less than 10%, often less than 1%, which is such a low proportion that it's prohibitively expensive to sequence them into just brute force sequencing them given the technology that we had available.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“That's exactly right. And this is like a brilliant idea that Ali had. And it really abandons the traditional approach of assigning statistical significance to mutations that cause a trait because we're just using an external piece of information, the correlation to traits measured in a completely different way to read off the probability mutations are real. So we can ask how much enrichment for real signal is there given a particular selection statistic and if it's halfway enriched to the plateau, the correct interpretation of that we're able to show is that 50% of the mutations are really selected. If it's three quarters of the way toward the plateau, there's a three-quarters probability that the mutation is real. If there's a 99% of the way to the plateau, there's a 99% probability that's real. So that gives us a calibrated estimate.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Mutations that are at random affecting the trait, it's like 60 or 70 that are affecting the trait. When we slide our statistic upward. And this is providing completely independent evidence that these sites are real. And as you slide above five, there's no more enrichment. So our interpretation of these results that we were able to validate and show that these interpretations made sense using computer simulations of our process, our interpretation of this result is that once you slide the statistic above five, essentially all the signals of natural selection are real.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“This is the statistic we use to measure whether a mutation is changing over time significantly in a non-zero way. So it can be approximately thought of as a normally distributed statistic, a Gaussian statistic. Which is the number of standard deviations, the statistical value is away from zero, where zero is no natural selection. It's not exactly that, but it's close to that. And so if this statistic is above five, we see about a five-fold enrichment in mutations that affect a trait. And so instead of 15% of the”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Hundreds and hundreds of traits. The whole genomes of all these peoples have been sequenced. And for each of these traits, we could look whether each of these 10 million positions are connected to this trait in some way, in a convincing way. So in 10 million positions, about 15%, about 1.5 million positions in the DNA are predictive of at least one of these several hundred traits. So then we could ask a question, is our natural selection signal, our statistic, is it related to whether a mutation causes a high blood pressure or some other trait? So we slid our statistic for natural selection from upward to a value of one, a value of two, a value of three, a value of four, a value of five. And as we did that, the enrichment for genetic mutations that affect traits got higher and higher. So whereas it was only 15% when we didn't use our selection statistic, when we required the selection statistic to be above about five,”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, when we got this result, we were very surprised, we thought it must be wrong, and we spent the next couple of years trying to make the results go away, but they just kept getting stronger. And so what we were trying to do is to look for some kind of independent type of evidence to tell us whether these positions were real. And we stumbled on something really powerful for this purpose that had not been used in this way before. And it relied on the fact that we had very large numbers of discoveries, like many hundreds of discoveries or even thousands. And so what we did is we took a completely independent data set, which was the corpus of genome-wide association studies. So these are studies that people have carried out in hundreds of thousands of people looking for whether particular genetic mutations are more common in people with high blood pressure than with low blood pressure or something like this. So we took the UK biobank, which is about 500,000 people from Great Britain who have been measured for”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Confident that they're real. We think that about 3,800 positions are all pushing in the same direction. So this is like a crazy number of results given that in our work previously in other people's work, there were at most a couple of dozen discoveries coming from a single scan.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So when we analyze the data this way, we looked at 10 million positions in the DNA that in these 22,000 people, 16,000 of them were ancient. And we looked to see if there was more change in this consistent direction over time than you would expect by chance. And when we analyzed the data, we found many, many hundreds of places in the DNA that were changing too much over time and too consistent a way to be explained by chance. Now, there's a bit of a statistical problem in figuring out how many there are because they're so densely packed that they're close to each other and they're interfering with each other. But when you try to piece them out and say let's look at, let's count them only one in each place in the DNA and blank out the others, we find at least about 479 positions that are all independently pushing in the same way. By another criteria of more than 50%”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So we're simply asking the alternative hypothesis is that selection has been blowing in the same direction at all times, and we simply ask if that explains the data better. And that's a dumb assumption, because, of course, the truth is that natural selection is going to have changed in frequency over time. But we're just asking the simplest of questions, whether assuming a constant rate of selection explains the data more than not doing so.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“In modern people. And then we look at how closely related each of these 22,000 people are to each other, and we predict the genetic type at each position in the DNA, at 10 million positions, based on the pattern of relatedness to all of the other 22,000 people. And then we ask if natural selection blowing the frequency of the mutation in the same direction in all geographic places and at all times predicts the data a little bit better than just knowing the relatedness.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The data in the ancient DNA literature so far comes from due to historical reasons, and it provides us with a natural laboratory where we can see what happens over one place over time as environments change to the genome. It's really interesting to imagine doing this type of analysis in other parts of the world, and the comparative analyses are super important and interesting. But this study right now is about this one place in the world where we have particularly fantastic data. The other thing we did is we developed an entirely new methodology that hadn't been used in this area before. And the methodology is based on a technique that had been developed for finding risk factors for disease in medical studies. And a simple way to explain it is we ask how to predict the genetic type a person has based on its pattern of relatedness to other people. So we'll have a data set of about 16,000 ancient people and 22,000 people if we include the age.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, what we did is we deployed a few innovations to try to improve our power to detect natural selection. One of them is we just pumped a lot of data into the system. And so we increased the amount of data by about 14-fold. And the main thing that we do in this study is we report data in this study from about 10,000 individuals with new data. So this is like a very big increase in the amount of data in the literature and the total data set size of ancient individuals distributed over the last 18,000 years is about 16,000 people. So this is a large data set. It's much larger than was previously possible. And when you have more data, you can estimate frequency changes with much more subtlety. And the data comes from only one part of the world, which is Europe and the Middle East. It's not a more important part of the world than other places, but it's the place where maybe 70 or 80 percent of”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“And found only 21 positions that were highly different in frequency across time. And while that was exciting, it was almost twice as many as we had found in 2015. In a lot of ways, it was disappointing because the sample size and data quality had gone up so much, and yet this is all that was found. And so what that suggested is that we might be hitting an asymptote and we might not be able to get beyond where we currently were, and that this approach to learning about biology, which was very promising in theory, might actually not produce a high yield. That may be in fact natural selection was quiescent, and in fact the reason we're seeing so few changes is that actually there's not been a lot of adaptive directional selection. So that was the situation we found ourselves in until just a few years ago when we carried out this study in our research group led by Ali Akbar.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“And we compared those ancient people who were the sources of modern Europeans to people in Europe today. And we looked at frequency differences that were too extreme to be due to chance. And we were very excited to find 12 positions that we were convinced were highly different in frequency between Europeans today and what we would expect based on the history that we and others had identified was the history relating modern to ancient Europeans. And so some of these were known and some of these were not known and this was very exciting. And we hoped that as the numbers of samples would increase and we would get higher resolution to be able to appreciate differences in frequencies over time, we hoped that this would make it possible to detect far more. And what was quite disappointing over the subsequent decade is that that didn't happen. So for example, the largest study of that type in 2024 by a group in Copenhagen analyzed the data, much better data than we had in 2014.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The first ancient DNA studies beginning in 2015 with this paper that we were involved in with Ian Matheson and colleagues. Indeed, these papers seem to show relatively small numbers of genetic positions associated with natural selection. So in 2015, we analyzed data from about 200 Europeans and Middle Easterners to try to understand frequency changes over time.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“I was involved in analyzing the Neanderthal DNA sequences, What happened was I found this very strong evidence of Neanderthals being more closely related to non-Africans than to Africans, and it was very surprising, and I thought it must be a mistake. I thought it was, I was quite incredulous, I thought it was unlikely to be true, because other evidence that had been found before seemed to point in the other direction. And so I spent several years trying to make these results go away, as did my colleagues, and we just couldn't make the results go away. They just kept getting stronger. And this experience working on natural selection was the same. So what we had felt here was that what we were convinced of was that natural selection had been pretty quiescent in our species over the last several hundred thousand years. Therefore, if we look at patterns of variation in non-African people today, or in any people today, we should see not a lot of selection going on.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The work that I've been involved in has consistently shown that I was wrong in my biases coming into the work. And I've really been almost traumatized by this. Like again and again, I've come into a project with some kind of guess about what the data was showing. And then the data doesn't show that. So for example, when I got involved in the Neanderthal Genome Project helping to analyze data, looking at how archaic Neanderthals were related to modern humans, I was part of a group of scientists who had established that non-Africans were a simple subset of African variation and that there was no evidence at all of Neanderthal interbreeding into the ancestors of modern humans or other archaic interbreeding. Different analyses that I and very much more other people had done made it look like non-African variation was just a subset, a small sample of that in Africa, and that could have fully explained the data. And so that went.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“To behavior. My understanding is, no. There begins to be busy making Lefala stone tools like Neanderthals for 200,000 years and not more impressive than Neanderthals in any way. And in any obvious way, as I understand. And then there begins to be in the archaeological record a quickening of sort of behavioral sort of traits, you know, which could be not genetic at all, or it could be genetic. Like, you know, there's lots of arguments about this. But people are obsessed with we were obsessed with intelligence earlier in our conversation, but people are obsessed with art and these things that seem important to us. But who knows what's important? And yeah.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Anatomically modern humans occur exactly here. It's the same moment. This is when they occur. The people who have skeletal features like ours and Neanderthals appear exactly then. This is when it all happens. So this is when we, there is this distance. Behaviorally modern humans, which is 50 to 100,000 years ago, but anatomically modern humans appear at this time and actually recognizable Neanderthals appear roughly around this time too.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“I think that this is what we're talking about, which is like if you look at the genetic variation going back 300 or 400,000 years, then we do begin to be places where all modern humans share common ancestry three or four hundred thousand years ago. And that's another way of saying there begin to be fixed differences at that time depth. So that is where you start seeing evidence for possible fixed differences. What's basically happening if everybody shares a common ancestor, 400,000, 500,000 years ago, is there a single ancestor at that time, and if you compared it to another population, like these guys, they would descend from a different lineage. So any mutation that occurred ancestral to that single ancestor would be a fixed difference. So, this is the time at which you can begin to see fixed differences.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Who knows? I mean, it could be that actually this was genetically driven. The time to, and we talked before about the time to the common ancestor of human genes, there's nothing at 100,000 years or 150,000 years. But there's a lot at 400 or 500,000 years. So if that's what happens and you have a mutation that occurs in the Caucasus or somewhere in the Middle East or Northeast Africa, and there's key genetic mutations that make people able to do this, and then this population expands, you know, when it moves into Europe, it's swamped by local genes, but there could be retention of those genes through selection as it expands. So maybe what you're actually seeing is that actually there are genetic developments. Most of the discussion on this, I point, has been focused on the 50 to 100,000 year event. And this is like anatomically modern human behavior. But this is like a lot of my archaeologists think this is an equally, if not more profoundly significant event in many ways. And why is that not the event that we should be talking about?”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“That's a great question. I think that we have to assume that there's a linkage between the cultural transformations in Africa and Eurasia at this time. And that's sort of not something that the community has really put together with the genetic data. So I think that there's this thread in the genetics about substructure in Africans. And then there's this whole world based on ancient DNA. And they've never been put together. So nobody's put together the extensive, now extensive work on modern human substructure with the now extensive work based on ancient DNA of archaic human relationships to modern humans. And if you put them together, you realize they line up in terms of their time of substructuring. So I think that I don't know if that's improbable. It seems actually parsimonious to me. But yeah.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“I don't know. I mean, nobody's thinking about this model right now. So, I don't know. It's just, I think that Know it seems like obviously a very natural model to me”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“But it could be made to work by proposing another complication and another complication, another complication. But this is not like as fantastic as proposing that everything revolves around the sun rather than the earth. But it is much simpler. And actually it explains many, many things.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“You patch it all together, you make these. It's a little reminds one of sort of what happened in the ancient world where there was this idea that the sun revolves around the earth, but it doesn't quite explain the movements of the planets properly. And so in order to get the movements of the planets to work right, the Ptolemian astronomers would have made up these epicycles, these special extra rotations and movements to make everything work about right. And it was such a convoluted model. And then when Copernicus and colleagues suggested instead that actually what's happening is everything's revolving around the sun, that is simplified things and made things ever so much simpler. So the situation that was happening is that as sort of astronomical information accumulated, it kept being contradictory to the standard model.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Yeah, I mean, you know, like, I think that the model that we've put together collectively about the relationships between archaic and modern humans is sort of accreted over time. There was this idea that modern humans are distinct and that Neanderthals and Denisevins are like sisters of each other. And then over time, we detected additional mixture of events like this modern human into Neanderthal and then this other ones I didn't even talk about, like super divergent lineage filling into Denise Evans and like all this other stuff. And we still say, oh, the whole genome says Neanderthals and Denisevins are sisters, so that's the truth. And we patched it all together and gotten it all to work. And oh, you look at the mitochondrial DNA in the Y chromosome and they have this odd pattern and it's improbable, but we can get that to work if we invoke natural selection, you know, things like this.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, as I said, this is probably wrong. I'm trying to tell you that we don't really know the world we live in. And this is not obviously wrong. In fact, to me, this is much more plausible than the model we currently sort of write down. It's probably wrong, but it's just much, much more plausible. It explains many more things. It's no more complicated.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“And so some people argue that level one technology is independently invented, but this would be a sort of, but it's very similar and this would be a way that it would have the same origin. Interesting. And sort of, so there's a cultural shared thread, this shared toolkit. There's a mitochondrial DNA and Y chromosome thread, which is, and then there is a”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The ancestors of Denisevans, and these are only 400,000 years diverged from these people over here. And here's African archaics. And these are like 1.2 million years diverge. So, you know, they just don't interbreed as much. And so you don't get as much, much gene flow. But the key thing is at the same time, it's the same time. So it really feels like the signature of an explosion of people from one place interacting with people here, interacting with people here. It's the same sort of Sort of cultural revolution or technological revolution impacting this place, impacting this place. And creating populations that are kind of both impacted by this cultural revolution, which we know is the case because they share the same toolkit.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“But this would be even bigger. So, what you would expect to see is that as this group spread, they would be moving into a territory full of archaic humans and there would be some interbreeding, but the kids would be not very fit, they would die off, there would be a lot of infertility. And so the barriers to gene flow or to interbreeding would be greater. So to me, it's not at all surprising that as this group moves into Eurasia, here's Eurasian Archaics.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Like, what you're seeing is this is a group that's actually completely permeable genetically or nearly completely permeable. This one is almost certainly has substantial biological incompatibilities because 300,000 years later, two or three hundred thousand years later, we see the interbreeding between Neanderthals and modern humans or between Deniseville as a modern humans. There's clear evidence of incompatibility at that point.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Here, it's like 1.2 million years. It's a lot. So these are at the edge of not being able to produce children. So this is quite different humans. These are actually three times closer than these. You know, and like if you look at mixtures of humans today, there are mixtures in Southern Africa today or people who are half this distance. If you look at Khoisan and Bantu people mixing in Southern Africa, like Rakhosa, which is the population of, for example, Nelson Mendela. Is groups that are separated by almost 200,000 years, which is half of this totally incompatible. And so”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“I think that this is not at all surprising given the context. So, if you look, if you think about this model, this is 700,000 or 800,000 years ago, this is 300,000 years ago, right? So this is like 400,000 years separated. You talked about the Bhatiya paper with me earlier. That's two populations, 70,000 years separated. There's no biological incompatibilities between West Africans and Europeans. There's no natural selection against biological incompatibilities. So we know Wendeanderthals and modern humans met and mixed. There were biological incompatibilities. That was at 700,000 years ago. And so as populations become more apart, there begins to be biological incompatibilities rapidly developing probably as the square of the distance separation because you need pairs of interacting genes and therefore it's the square of the separation. So here it would have been maybe only 400,000 years separated between this lineage and this exchange.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“It's the weakest link in this argument. This argument is probably wrong, but I'm just telling you what I'm thinking about.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So it's a question. So there's multiple possible explanations, but it's much easier to explain that than both mitochondrial DNA and the Y chromosome. One possibility is that the mitochondrial DNA was less biologically fit. Another possibility is that there's social discrimination against people based on whether their parents are archaic or mortal.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“with many women. And so there's competition among men for kids. So in this context where males are competing for access to females, then female make choice begins to be an important process. And you have a phenomenon where it could be the case that if your dad is an archaic male, then you're not going to be as successful in the competition for local females if your dad is a non-archaic male. So simple social phenomenon like that could explain the data. And we actually see this in human society. So for example, if I remember right, like in Central African rainforest hunter-gatherers, there's different treatment of boys and girls depending on whether their dad or mom is one group or the other.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“It won't solve the other one, so you need to solve the other one. So the other one you can solve either by natural selection or you can solve it by social selection. So, by the way, patrilineality and matrilineality are the rule, not the exception in human communities. Usually communities sort of follow have continuity along the male or the female line. And usually it's patrilineality. Sometimes it's matrilineality. You can also have phenomena like social selection. So it could be that once you have kids of someone who is from the whose father, for example, is from the outside community that those the male, usually in most communities, females all reproduce. Like that's typical today. Like usually women have kids if they can. But men in traditional societies are actually very variable in their reproductive success, a large fraction of men never have kids. And then there's a relatively smaller number. There's a subset of men have many kids.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, if that happens, it guarantees one of these two parts of the genome to look like it does. Because it's a modern human expansion. If it's patrilineal, it will retain the Y chromosome. If it's matrilineal, it will retain the mitochondrial DNA. So it will solve one of your two problems.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, the reason I'm talking about these matrilineal or patrilineal expansions is I'm really troubled and have been troubled for like many years, actually 15 years, but like especially in the last three or four years, by the fact that the mitochondrial DNA and Y chromosome cluster Neanderthals in monotheums, but the rest of the genome clusters Neanderthals and Deniseans. This is like a crazy result that is not seen in any other species where you see this pattern. So I'm very interested in patterns that would explain this. If you invoke and assume that there was like a matrilineal or a patrilineal expansion, it could be either, where modern humans, when they were expanded across the landscape of Europe, retained their identity along one of the lines. Like if you incorporate a local, if it's natural linear when they incorporate a male from the local community, they brought into the community and the kids are raised by based on the culture of the mothers or something.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“There's just been a lot of mixture on the way, but it is the tracer die, right? It tracks into a European language, is important aspects of Indo-European culture are coming through Yamnaya. So if you know where to look, that tracer die is only 10%. It's only 5%. It's only 2% in some groups, but it's the languages people speak. And it's important cultural shared elements that connect them to people on the other side of the Indo-European-speaking world. So this 5%, you shouldn't sneeze at it, right? Like that's tracing something important. This model”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“It spreads through genes too. If you look at Yamniyah in India, there's almost no Yamnaya ancestry in India. I mean, it's just diluted, diluted, diluted down As Yamnaya expanded into Central Asia, expands into Europe, it makes the courted wear. There's a 25% dilution. It expands back across Central Asia. It goes through the Hindu Kush. It gets into northern South Asia. It mixes more with local people. By the time, you know, today, the most Yamnaya ancestry you see in India is 20% or most people have less than 10% or 5%.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Okay, great. All of these groups have this. Maybe it's in slightly different proportions. So you ask where are these people living? Who knows? In this scenario, the 80% is coming from the Caucasus or Northeast Africa, where this Middle Stone Age form. It's from this population that forms the Middle Stone Age. And they mix with like local groups. And who knows where they are? Southern Africa, Western Africa, Central Africa, Eastern Africa. We don't have any ancient DNA. But this is a very rich environment people have been living there for seven million years at least. And like there would have been different groups of people everywhere. Probably it's not just two groups. It's probably more groups. I think the important theme here is there's evidence of substructure that's well more than a million years ago. And this place would have been a landscape full of archaic humans that would have been differently related to these expanding people and would have admixed with them when they came through.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So the genetic data suggest, this is analysis not of any ancient DNA, but only an analysis of modern DNA from different people, mostly in Africa, but also non-Africans. And multiple studies, there's at least three, maybe four or five studies that I know about, have looked at the patterns of variation in people today and say the data in modern people today, including in Africa, is not consistent with a homogeneous population. It looks like a population that split well more than a million years ago into multiple, at least two, but maybe many groups, and then came together with an important coming together a few hundred thousand years ago. The papers have different models that they fit, but they all have this feature of more than a million years ago. There's a split up. And then on the order of a few hundred thousand years ago, there's a coming together and a remixture event forming the ancestors of anatomically modern humans.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“300,000 year old event, their shared toolkit. So even though the genome is telling us that their cousins of Neanderthal, Denise Evans, the actual correct way to think about them may be in an important sense somehow”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Seeing as a modern human expansion, both into Europe and into Africa, in one place it forms Neanderthals, in one place it forms the ancestors of everybody living today. But all of these groups are descended from this key sort of revolutionary event that happens here. So we often talk about the revolutionary events 50 to 100,000 years ago, the more symbolic behavior and so on and so forth, that sort of first appear in Africa and the Middle East and spread beyond. But there's also this earlier event. And this event is sort of contemporaneous with the breakup of all the different groups also in Africa today, you know, the Khoisan Southern Africans and the Central African Rainforest Center gatherers. So one wonders whether this is an equally important formative event. And it also, if that's true, makes you think of Neanderthals as actually somehow our cousins, that they're actually share our Y chromosome, they're share our mitochondrial DNA, their share formation of two or three or”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“or Lavawatt technology, this one that appears here. And it expands in all directions into Europe here, into Africa here, two to 300,000 years ago, bringing this technology, bringing these new ideas, bringing perhaps some genetic adaptations. It expands into archaic humans in Europe. It mixes with the local population. It gets 95% replaced, but still retains its cultural features and maybe some genetic features. And it expands in Africa too. And here it's not 95% replaced. It's only 20% replaced. And probably the reason that happens is that this group is much, much more diverged. It's much more archaic. It's 1.5 million years diverged rather than 7,000 to 800,000 years diverged. And as a result, there's many more incompatibilities genetically, and there's much more barriers to gene flow. But there's still a lot, maybe 20%. And we have evidence that this is a big mixture that happens. And so what you're actually...”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source