YouSaid · the spoken record

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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“And that they come together $200 to $300,000 ago with like 20% to 300,000 years ago, with maybe 20% ancestry from this archaic. African group and 80% ancestry from this early modern lineage, and that the same group then mixes with With Neanderthals, and it's 5% modern here and 95% local here. And so you actually have this key population that makes the Middle Stone 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 maybe what we're seeing is that this is what's happened. You have like a modern human population that's matrilineal, for example, where transmission of making stone tools this way is happening from your mother to the kid. And that's why they're retaining their mitochondrial DNA. But by the time they get to the other end of Europe, they're mostly archaic. They're mostly local archaic. So you end up with a 95% population replacement. So this would explain why the mitochondrial DNA is shared between Neanderthals and modern humans. And it would also explain why the mixture proportion is only 5%. But the really interesting thing is that actually there's other evidence from studies of modern humans that actually modern humans are also admixed and that the right way to think about this is that modern humans are a mixture of two groups, maybe like one”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Can break it up into 100 or so dams, little areas. And modern humans get introduced at the bottom right corner in the Middle East or something, and they spread into Europe. And as this population spreads, there's a wavefront of expansion and they're interacting with the local archaic humans. And even if there's a small amount of interbreeding, the theory from lots of studies, simulations, and lots of studies of all these different species like mammals and birds and so on shows that there is when there's even a little amount of interbreeding as there's an invasion or a movement of expansion of one group into the territory occupied by the other, there's massive introgression of local genes. that these pioneers at the wavefront, they'll sometimes interbreed with the local population. There's so many of them around that their DNA will get swamped by the local group. So by the time they make it to the other side, they're largely local.”
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 findings in the whole literature so that we make ourselves believe this, but it seems sort of unlikely on first principles that somehow only 5% will introduce both the Y chromosome and mitochondrial DNA. And it really looks like this. So there's this amazing data from this site in Spain that's like 200 to 400,000 years old. It's 3,000 to 400,000 years old at site called Sima de los Huezos. And they have a nuclear genome that looks Neanderthal-like most of the genome, but their mitochondrial DNA microchromosome was Denisovin-like. So it really looks like there was a population related to modern humans that pushed into this sema de la suasis-like population, displaced its mitochondrial DNA and Y chromosome, but kept the rest of its genome. So it really looked like something like this happened. So the idea that I'm sort of playing with, and probably it's wrong, who knows, but is that there's a landscape, this is maybe Europe.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Neanderthals in modern humans cluster. So if you look at the mitochondrial DNA, Denisevins in modern humans share an ancestor well more than 700 or 800,000 years, as you expect from the history. And if you look at the Y chromosome that you get from your dad, Denisevins and modern humans share ancestor more than 700 or 800,000 years ago, which is consistent with this history. But if you look at the Neanderthal mitochondrial DNA, it's only 300,000 to 450,000 years. If you look at the Y chromosome, it's only 3,000 to 450,000 years. So what the current genetic work is asking us to believe is that even though this is only 5% of the whole genome, it introduces mitochondrial DNA and Y chromosomes, and they jump up to 100% frequency. It's kind of a crazy claim because the probability of this occurring by chance is low, maybe 5% times 5%, so a very small number. And so it's sort of what we actually all believe, but it's sort of a very sort of surprising event. And somehow it's a creep.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The Middle Stone Age, the Middle Paleolithic, sometimes called Levala technology, and that people from this population expand into Europe and they mix with the local archaic humans who are there. And that is what this 5% interbreeding event is. It happens two to 300,000 years ago. And it produces a group that as it expands across this landscape in Europe, mostly picks up the local DNA and becomes mostly archaic genetically but retains its modern human culture, the way of making stone tools and some of its traditions. And so one of the things that's super interesting about this is that if you actually look at the genetics, the whole genome, the Neanderthals and Denisovans cluster. But if you look at the mitochondrial DNA, which people get from their moms and they get from their moms,”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“We know that the new way of making stone tools with these cores that were very carefully mined far away from the locations they were used, made out of high-quality stone like flint, start being used three or four hundred thousand years ago, first in the Caucasus, places like Georgia today or East Africa, and that this way of making stone tools, which is quite revolutionary and is known in Europe as the Middle Paleolithic and Africa, the Middle Stone Age, and is associated with much more widespread use of fire and also moving stone around at much further distances than before. I'm interested in the idea that this is something that's shared between modern humans and Neanderthal. That's absent in East Asia, and that might have a relationship of the genetic data and is somehow related to this 5% DNA. So the idea I'm interested in is the possibility that there is a population here that invents”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Ancestors of modern humans. So I'm interested in the possibility that actually the right way to think about Neanderthals is actually as somehow culturally modern humans. And even though that genetically, they're mostly Denisovans. And the model I'm thinking about is motivated by this archaeological phenomenon known as the Middle Stone Age Revolution. So if this is Africa and this is, I don't know, Europe.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Contributing DNA to the ancestors of Neanderthals. So this is maybe 5% of the DNA of Neanderthals comes from this interbreeding event in a lot of studies have shown this. And so I'm very interested in this because actually from the archaeological record, Neanderthals and modern humans sort of look actually quite similar to each other, much more similar to each other than a lot of them do to Denisevans, these archaic humans in East Asia. So a lot of the history people have thought that Neanderthals are our sister, but in 2010, the sequencing of the Denisevin genome made it very clear that on average, Denisovins are closer to Neanderthals than to modern humans. So this was like a very confusing result. And most people now think that Neanderthals and Denisevins are descend from a common ancestral population, separated earlier from the”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The thing I'm thinking about a lot recently is the possibility that it's maybe we're not thinking in the right way about the relationship between archaic and modern humans. So the standard model is one like this where Denise Evans, these archaic humans. Descend from a common ancestral population five or six hundred thousand years ago. And that these two separate earlier, maybe 700 to 800,000 years ago. From the ancestors of modern humans, people like us. So that's the big result of a lot of studies since 2010. But there's also evidence of interbreeding events that happened maybe 200 to 300,000 years ago. And that actually resulted in 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
“I think that's the main thing that I'm thinking about a lot these days. I think that I'm really continue to be very obsessed with questions about the spread of human populations around the world and trying to reconstruct that with ancient DN”
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 same reason that if you have a sister, you're in some places in your DNA more closely related to her than you are to me because you share a parent. But in other places you're more closely related to me than you are to your sister because you happen not to share the same DNA from your parents. It's just that the DNA that we get from our common ancestral population was already quite variable. 500,000 years ago, 700,000 years ago, a million years ago, and some of us descend from some of those ancestors and others of us descend from other those ancestors. And Neanderthals split from our lineage really close in time on human evolutionary timescale, such that in some places in our DNA we're more closely related to the Neanderthals than to each other.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Yes. So the average times the common ancestor of any two human genes is one or two million years ago. So if you look at a bit of your DNA that you get from your mother and a bit of the same bit of your DNA on the same chromosome, the copy of chromosome three you get from your mother and the copy of chromosome 3 you get from your father, typical time they share common ancestor is one or two million years ago. That's before the split from Neanderthals and Denisovans. So there's many places in your DNA where you're more closely related to a Neanderthal on your mother's side than you are to your father.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Is crazy. Yeah. Well, the divergence to all the archaic humans, including Dionysovins, is within human variation. Wait, what?”
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 a known interpreting event from the lineage leading to modern humans into Neanderthals, but it's supposed to be only 5%. So I'm interested in that 5% is actually a sign of something much more impactful. That is, that somehow Neanderthals are in some sense deeply modern in some ways. And even though they get swamped by archaic genes, that somehow they actually have more of a modern impact than one would think and that the Middle Stone age and middle Paleolithic revolution that they share with modern humans is actually more fundamentally a part of who they are in some sense than we think.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Between the Neanderthals and modern humans that's not shared with Denise Evans, even though the vote of the whole genome says that Denisevins and Neanderthals are related. So one wonders whether there's something connecting kind of Neanderthals and modern humans that's different from Denisevins, even though genome-wide Denisevins and Neanderthals cluster. So I'm thinking about that all the time now.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“$700 or $800,000 ago from the common ancestors of modern humans. And so genetically, the whole genome data says that Neanderthals and Denisovins are archaic humans from a common ancestral population. But there are so many things shared between Neanderthals and modern humans that don't seem to be shared with East Asians. They both share Middle Stone Age stone tools, level wild technology, this cognitively unique type of way of making stone tools that wasn't used in East Asia. They both have the same mitochondrial DNA and Y chromosome sequence. So the Y chromosome sequence of Neanderthals, the mitochondrial DNA of Neanderthals is actually modern human that came through interbreeding two or three hundred thousand years ago and then shot up to 100% frequency. And then Neanderthals and modern humans are both the product of mixture events that happened between archaic and modern humans, 300 or 200,000 years ago demonstrably through patterns of variation in ancient and modern DNA. And so it feels that there's something shared.”
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 I'm perplexed. I don't know if we talked about it before, but I remain very, very confused about the relationships between archaic and modern humans. We have genome sequences now from archaic humans who lived in Europe and the West Eurasia and Central Eurasian Neanderthals. We have archaic sequences from these enigmatic Denise events who we now have a skeleton for since we last talked. There's now a skull from a Denisovan that's been shown to be a Denisovin. And we have data from lots of modern humans. And there's really big mysteries about the relationships amongst these groups. So genetically Denisevins and the Neanderthals are sisters. They descend from a common ancestral population five or six hundred thousand years ago. And that groups descends a couple hundred thousand years before”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Right. Like, take any person who has an old Will World superiority and take them to these places, and they will not have it anymore. It's just extraordinary what's in these places. And these are people who separated 20,000 years ago at least from the ancestors of East Asians and 40,000 years ago from the ancestors of West Eurasians. And just had the same biological cultural shared toolkit from then. But there's just a fuse, a long fuse delay until all this stuff happens. It's kind of like an amazing thing and we don't question it.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Oh, yeah, I mean, there's like, you know, we should go for a trip to Teotihuacan in Mexico. And it's like so impressive. Like, you know, when I went there, when I was 20, you know, it's just like, it's totally as impressive as ancient Egypt. It's like huge. It's massive. It's without metal.”
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 we would see their archaeology. And like, you know, the extraordinary developments in the Americas, which are entirely Stone Age. You would even see that.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Then ignites into agriculture and all these other things after that point. It's kind of a crazy claim. And then you could argue about whether the actual fuse is 300,000 years, you know, from when Neanderthals separate and from when different lineages of extant modern humans separate. And that's also plausible. So it's kind of a crazy sort of set of things that we're being asked to believe.”
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 very, very surprising. And I think we accept it, but it's just like a crazy observation that most normal people don't realize. The thing that basically everybody accepts is that the common ancestral population of almost everybody in the world except for rainforest hunter-gatherers and Khoisan is like around 70,000 years ago. And everybody accepts that these people all have in place the cognitive, behavioral, intellectual ingredients that are necessary for the farming revolution and state building state societies. Because when these descendants of these people get distributed to West Africa, to East Africa, to the Americas, to Europe, to South Asia, to East Asia, to New Guinea, and so on, their descendants all do this. Like independently or semi-independently or completely independently or demonstrably, completely independently in all these different parts of the world. So the cognitive resources for doing this must have all been in place, but it's a very long fuse. Like delays for 40,000 years, for 70, you know, 60,000 years in all these different places after the common ancestral population splits up.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Like, I just don't know. You sort of distribute these people descended from this diversification that happens 200,000, 300,000 years ago to different parts of the world. And then bing, you know, after 12,000 years ago, you start having agriculture popping up in different places. It's kind of an outstanding mystery of human history. And I find it unbelievable that we live in a place, in a time period that climate ecologically is so unique on a scale of two million years. But my colleagues tell me it's true.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Or 200,000 years. And all of these people are capable of going to college and doing everything. And so it's not obvious that all the toolkit, the cognitive toolkit, the behavioral toolkit, the genetic abilities were not all in place two or three hundred thousand years ago. And that even Neanderthals had them, right? So it's not obvious that this was not the case. 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
“400,000 years ago, this invention of Lavois technology, the ability to make stone tools out of cores, the Middle Stone Age revolution or the Middle Paleolithic Revolution, depending on what you call it in Africa or Eurasia. And this is a revolution, a new way of making stone tools that's shared by Neanderthals and by modern humans, but is not shared in Eastern South Asia. And it's a big change and it involves a cognitive change, presumably, in order to make this sort of technology. And then there's a further change to the Upper Paleolithic later Stone Age, maybe 100 to 50,000 years ago, when there's the second transition where the new type of toolmaking, but not as revolutionary as the earlier one. So when the cognitive leap happens is unclear, the diversification of the lineages leading to people living today like Khoisan, Southern Africa's and rainforest hunter-gatherers, and that all occurs more on the timescale of 300,000.”
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. Like, I'm thinking about this all the time right now. This is actually actively what I'm thinking about right now. And like, you know, there's a big transformation in terms of the culture of humans, 300.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Ago, we switch into this period of not just warmth but climate stability. And that actually this is true and sort of hard to believe that we're living in such a special time. But if you look at, for example, data from the bottoms of ponds where you can measure the fluctuations of temperatures using isotopic signatures, apparently we're in a period where it's just fluctuating a lot less year to year and 10 years to 10 years and 100 years to 100 years. And it's just a period of relative stability that we are miraculously living in. And that when this period of relative stability happens, somehow it follows that multiple groups independently turn to agriculture, even though the genetic complement, all of whom have the same genetic complement that arises 50,000, 100,000, 200,300,000 years ago. It's kind of a crazy observation that people just accept, but it's like unbelievables.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“That is such an interesting question, right? Genetically, we're there. The common ancestral population has all of the ingredients for farming 50,000 years ago. And these people are distributed into different parts of the world. The Americas, you know, 15,000 years ago or whatever it is, New Guinea, 40,000 years ago, East Asia, Europe, West Africa. No farming develops 12 or 11,000 years ago. It only develops in the last 12,000 years, the period known as the Holocene, which is sort of the end of the ice age. And if you talk to climate scientists and archaeologists, I keep asking people this question every time I meet someone who's an expert in this. It's like, how can this be that farming develops in all these places? Are we really living in such an unusual time? And people tell me, indeed, we're living in an unvery unusual time on a scale of two million years. That is, 12,000 years.”
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 a lot of us in human genetics think that our population contains within it the clay that's needed to make almost any trait. And that depending on environmental conditions or selection conditions, the mean value of these traits will move in different directions. There's an empirical question, a real question about how much selection there's been in different human populations over time. One of the things this new work that we're involved in is doing is showing that at least in the last 18,000 years, 10,000 years, 5,000 years in this part of the world, there actually has been significant movement, at least for a handful of important trades. We looked at more than 500 traits, about 100 of them complex traits showed significant movement in systematic direction over this time period. So it really does seem that there is a response to the environments people are living in that has occurred over this period and is potentially stronger than in previous periods.”
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 100 to 50,000 years ago, and this is the population that's ancestral to West Africans, to most East Africans, to all non-Africans. And there's a couple of populations in Africa that have substantial ancestry that comes from more divergent groups. For example, Khoisan from southern Africa or Central African rainforest hunting gatherers have substantial fractions of their ancestry from groups that diverged maybe 200,000 years ago from the other lineages. But all of these groups today are able to do, go to college, do everything everybody else does. And so there is like no evidence that there is any key mutation lacking in some groups that are not present in the others.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“To help the population to move to a new set point, but there's no key biological change that rises to high frequency in this time.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“We looked across the DNA for places that might be expected to look like this, that where all people living today, or nearly all people living today, share a common ancestor, maybe 100,000 or 200,000 years ago. And we looked really hard. And right across all the DNA we could look at, we couldn't find anything more than four or five hundred more recent than four or five hundred thousand years ago. This is like a crazy result because it looks like there's no keen selective sweeps that have occurred in this period that is ancestral to everyone living today. We talked before about no selective sweeps between Europeans and East Asians, but there don't even seem to be any selective sweeps between shared between all humans in this really important period when a lot of evidence and the material culture record appears. And so it could be that there's biological adaptation in this period, but it's polygenic. There's lots of mutations that all shift in the same direction.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“50,000 years ago or so, or maybe 100,000 to 50,000 years ago, there's a quickening of the pace of change in culture. So people, you see the first extensive representational art and B necklaces and drawings on the wall and so on and so forth and also a rapid increasing pace of innovation, the types of tools that people use. And so the thought might be that there was going to be have been some kind of genetic switch, a kind of important genetic change that was occurred in the population and that swept to high frequency, that everybody suddenly had, soon had, and that made it possible for these things, maybe some genes that allowed people to have complex language, representational language, for example. And so one thing that we did in 2016 in this paper by Shap Malik and colleagues”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“If you are talking about mutations of the type that will start rising in only in large populations but not small populations, those are selection coefficients that are on the scale of 1 over 10,000 or 1 over 100,000. And those ones will take 10,000 or 100,000 generations to rise in frequency, which is hundreds of thousands or millions of years. So that's not going to do anything over the time scale we're talking about. There's just a timescale issue. We're talking about strong measurable selection coefficients on the order of half a percent or more in this study, and all of those are going to work in small populations or large populations. It's not going to be affected by the population size.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Think about with natural selection, and that is true that in small populations, selection doesn't work effectively. And that's because mutations bop around in frequency from generation to generation a lot in a small population just randomly. So if you have a population of size 1,000, populations, mutations will pop around by a frequency of 1 over 1,000 every generation. And if the selection coefficient is less than that, it will be drowned in the random bopping around of frequencies due to genetic drift. But that is already for a population of 1,000.1% selection coefficient. It's very weak. We're talking about 1% effects, and that's very strong. It will work very well even in a population of a size 1,000 or 10,000.”
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's not likely to be true, but it's an extremely interesting thing to think about. So I think already when population sizes are on the order of a million or so, every mutation that can occur does occur within a few generations. And so that's well before the Bronze Age, if you take the population, even of a place like Europe, but also of other places, or maybe it's at the dawn of the Bronze Age or the farming period. So the question you ask is maybe when the population is small, natural selection doesn't work effectively. So a common thing that people”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“There are maybe 30 new mutations every generation, so that's like, what is it? It's like 240 billion new point mutations every generation. There's only 3 billion DNA bases in the genome. So every mutation that can occur does occur about 100 times every generation. And we're not mutation limited anymore. And so it's not like you have to, the mutations can arise again. They do arise again. But when the population is only 10,000, you have to wait dozens or hundreds of generations sometimes for the new mutation to occur.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“The population can rapidly move to a new adaptive set point. There are some unusual traits like ability to digest cow's milk or protection against sickle cell anemia that require a single very important mutation that may not yet exist in the population. And then you have to wait for the mutation to occur in some people. And when the populations are relatively small, only 10,000 people, you might have to wait dozens or hundreds of generations for that mutation to arise. But when the populations are large, there's not mutation limiting anymore. Every mutation that can occur does occur. There's 8 billion people in the world.”
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 rich question. And I think that the human population has within it for complex traits a tremendous amount of variation. So within the human population, there's a huge amount of variation that affects height. There's a huge amount of variation that affects body mass index. If you take all these mutations and all set them to the high height variant, a person will be extremely tall, like as tall as a tall building. Of course, which will never happen. But if you take all these variants that affect schizophrenia risk, they will, and you point them all in the same direction, there will be extreme risk or extreme protection for schizophrenia. So for complex traits, one's underpinned by many mutations, all the variation already exists to move the population to a different adaptive set point that's optimal in the environment which it's in. hundreds or thousands of years”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Think there's more room at the top for a lot of these traits. I think that you can move height very extremely in one direction much more than it is today. You can move any of these traits, much more extreme in the other trenches. There's probably very strong negatives to doing that. You're probably sacrificing other things. And I think that there's trade-offs probably. But I think it's highly likely that if natural selection was pushed any of these traits in more in one direction than it is, the mean would move.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“But selection might not be acting on that three year time period. Your fat store from the latest hunt is not going to carry you through to the famine three years later. And so survival of famines is a different thing than building up body fat for being able to survive two weeks later.”
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 there's a timescale issue You're absolutely right. So I think, as I understand it, I'm no anthropologist and my understanding is that when there's a hunt in some of these in traditional societies or communities that hunt, people will often gorge themselves and eat a huge amount and build up a sort of temporary store of fat and then go with multiple days without eating meat sometimes until the next hunt. And so there is this sort of boom bust access to high value nutrition that is not true to the same extent in farming communities. On the flip side of this, these famines are, I think, something that occurs more commonly in agricultural societies. But the timescale and the tempo of them is very different from the hunting tempo. So maybe there's a famine every three years. And indeed, if you look at the bones of farmers, at least in some communities, there's more stress in them, maybe due to a famine every three years or a famine every five years.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Group of people in Europe and the Middle East over the last 10,000 years has moved into a period of relatively more stable food where building up stores of fat are not as advantageous and there's been selection against this combination of traits. Europeans actually are a relatively better protected genetically against type 2 diabetes than some other populations around the world like African Americans and Native Americans that have perhaps not been as exposed to agriculture for as much time. So you may be seeing the effect of more exposure to more stable food accessibility.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, this is what you see as a reduction in the combination of genetic mutations that make you at risk for obesity, body mass index. And similarly and very correlated to it, higher fat mass, higher waist to hip ratio, higher type 2 diabetes risk. And so there is clear selection by about a standard deviation on the scale of modern variation for these traits, reducing about over the last 10,000 years in this part of the world. So what can be going on there? Why was there not selection for this combination of traits before? There's a long-standing idea known as the thrifty genes hypothesis. The idea is that once you have hunter-gatherer populations that move into a farming environment where there's plenty of”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Are being asked to believe in visions. Yeah, exactly. You know, and even today, I think there's valuation in some religious communities and, you know, communicating with God and having visions and having supernatural communions. And so... I just don't know. But I think it's super interesting to ask the question why certain traits are not always advantageous. For schizophrenia and bipolar disease, there is a sense in which most of the mutations are disadvantageous. We can see that from the patterns of variation where the variants that are risk factors tend to be low frequency and they tend to be small effects.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Spectrum of traits that actually in some contexts might be advantageous, may be being anxious or being imaginative or being neurotic might be helpful in a shamanistic tradition, in a religious tradition which values people who can have visions or values people who can be creative. And maybe these are subclinical versions of schizophrenia or bipolar disease that in certain times may be advantageous and in other times may be disadvantageous. Maybe you're just seeing selection from different types of creativity or other thinking that can be valuable in different contexts. I'm waving my hands here, but my sense is that these complex traits have not pushed in one direction because there's advantages, there are spectrums where there's advantages to both ends of the spectrum and there's multidimensional impacts of these different traits.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“But that is an effective way to produce offspring in certain conditions. So there'll be a toggle depending on the environmental conditions back and forth between investing in large numbers of offspring with fewer and less investment or smaller numbers of offspring with more investment. And maybe we're just seeing that move back and forth over different places and times. Similarly for schizophrenia and bipolar disease, how could this ever be advantageous? But maybe what we're seeing with these diseases is a kind of readout of some kind of”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“Kid, you're going to have a lower fertility and you're going to have fewer kids, and that's going to result in lower fertility, but those kids might survive more and do better in society. Alternatively, you can just have as many kids as you can and invest less in them. They might have individually less good outcomes, but in a time of plenty, which is potentially Iceland in the 20th century, it might make sense to have more kids and invest less in them. And so there's a toggle between having more kids and investing less than them and having more kids and investing less in one's life and having fewer kids and investing more in excelling in various ways or something like this. And so you can imagine that actually at different times and in different places in ecology, there's resource, there's different ways like mammals often invest a lot with a pregnancy and a small number of children, whereas fish will spawn huge numbers of offspring into the river. The great majority of whom will be eaten.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source
“So, I'm being very speculative. And let me give you two examples about, in my head, how I'm thinking about this, and not that I'm a particularly good authority on these things. But as I mentioned, a lot of these traits, which are quite disparate, are highly correlated to each other. Obesity, years of schooling, walking pace, you know, performance in IQ tests, household wealth, all these crazy traits all seem to be governed to a substantial extent by a shared combination of genetic variants. And let's just think about what this might mean. So in Iceland in the last hundred years, there's been selection against this combination of variants. And one possible interpretation is it's basically selection for two ways of investing in your children. Having many kids and not investing a lot in them, or having few kids and investing more in them, right? So if you invest in deferring having kids but becoming, you know, having more wealth, having more resources, and putting more into each other.”
2026-05-08 · Dwarkesh Podcast · David Reich – Why the Bronze Age was an inflection point in human evolution · IDENTIFIED FROM THE TRANSCRIPT · source