This podcast is brought to you by the Albany public library main branch and the generosity of listeners like you. God daddy these people talk as much as you do! Razib Khan’s Unsupervised Learning
So this is Razib Khan with the Unsupervised Learning podcast, welcome to this week and I do not have a guest. I am going to be holding forth I guess on a particular topic, which is kind of a broad topic is Homo sapiens and the conquest of the earth. I'm really focused on what used to be called Homo sapiens sapiens. I think they now call it Homo sapiens. And there's Homo neanderthalensis, and all this stuff. I am not a believer in separating Homo sapiens from Homo neanderthalensis, but I don't get to decide that. So I might use it interchangeably, sometimes. But really what I mean human I mean, everyone one to 2 million years diverged. And then modern human, I mean, people with flat faces, higher foreheads smaller chins, people like us - small kind of pointy chins, you know, Neo Africans, descended from one of the African populations and started expanding 3 to 400,000 years ago. And, yeah, so Homo sapiens. And the purview of this podcast, will be basically the emergence of modern Homo sapiens of anatomically modern humans. Geneticists, sometimes called stem humans, because they're 95 to 99% of our ancestry. And within Africa, there's some arguments about various things related to what proportion that is, whether it's 100%, whether it's 85%, depending on, you know, Sister lineages that were there, I'll get into a little bit of that, but mostly, I'm going to cover the out of Africa movement, because that's really, really confusing for a lot of people, especially, you know, over the last 20 years, because out of Africa, has been in the zeitgeist for 35 years now, but over 35 years, actually, based on mitochondrial DNA, but there's been a lot of changes due to genomics, due to fossils, due to ancient DNA. So these updates are kind of interesting. They're interesting to me, they're fascinating to me, but you know, they make it so that a lot of people have a hard time tracking and hard time following it. So I am here, kind of, you know, I'm going to outline I guess the recent discoveries and my perception of them in you can take it as it is, right, but there's a lot of papers out there. There's not too many books, you know, maybe Chris Stringers book, which is already out of date. I think it's like five years old now. I mean, Chris says it's out of date. “Lone Survivors” is pretty good. There's some ancient DNA books, you know, David Reich has a famous one, but Johannes Krauss has one. Tom Higham has one. There's, there's some stuff out there to read. But, you know, this podcast will be an okay intro, I think, mostly informed by genetical genomic perspective, but I’m not totally ignorant of fossils and bones. And I can tell a Neanderthal skull from a human's go, I mean that's pretty good. I mean, it's not impressive, but it's pretty good. I think. So, you know, let's start here. So, we will start, approximately, I don't know like 250 350,000 years ago, right. So basically, if you are talking 20 years ago, if someone was to tell you about, you know, recent human origins, so there's not recent human origins. So not recent human origins includes words like Homo antecessor, Homo heidelbergensis, Homo erectus, which is kind of like a catch all category, you know, about Australopithecus afarensis, which is not a homo, which is really old, I think, Lucy was an A. afarensis, Australopithecus africanus, Australopithecus robustus, or P. boisei - You know, there's all of these human species, and they're defined by very, very different morphologies. You know, some of them have, most of them have stronger facial features than us, like, you know, stronger brow ridges, smaller cranial capacities, all of these things. I'm gonna be talking about recent human origins, I mean, talking about our lineage of STEM humans, anatomically modern humans, etc, etc. Humans, qua humans, you know, and so that's gonna cover the last three to 400,000 years. But I do need to say a few things. Just to kind of set it up because we are going to encounter some, I will say cousin lineages, Neanderthals Denisovans. In my story, basically, three or 400,000 years ago, there were a lot of different types of humans. So there's Denisovans, who are actually divided into many different groups that are more genetically dissimilar from what we can tell than any modern human lineages are from each other. So, probably the deepest cut that you have is Khoisan versus non Khoisan, the San Bushmen, the Khoi pastoralists. And between all other humans 200,000 years ago, on the order of 200,000 years ago, maybe 150, depending on how you do the parameter settings, but Denisovans might have separated as much as three 400,000 years ago between some of the disparate lineages. And I think that this is because, um, you know, I talked about in the podcast on China, which you can listen to, if you are listening to this one Denisovans range from Mongolia, all the way down into Southeast Asia, probably into Wallacea, right there all over the place. Neanderthals you probably know about very homogenous lineage. They occupy the territory from basically modern day Spain, all the way to Mongolia. They don't really ever go south of maybe Israel, Lebanon, they tend to get pushed north sometimes push south, sometimes, depending on the climate. Then you have the hobbits, you know, on Flores you have, it looks like another similar type of human species. In the Philippines, there are some hominin remains that are labeled as H. erectus very late in Java, Java, man and whatnot. So that's, that's the thing. And we know from looking at extremely, extremely high quality ancient genomes of Neanderthals from Mongolia, using various inferential methods, it seems, it seems highly likely I would give the estimate 80% 85% How much I trust the statistical, you know, Arcana, that these Mongolian Neanderthals, I mean, I'd say 90%. These Mongolian Neanderthals had some amount of ancestry from a lineage that was related to ours. So by that, I mean that they had expanded out of Africa considerably earlier than us. But they were related to us. They're probably some sort of African human lineage that expanded into East Asia, there was probably another one that also expanded into the Neanderthals. And we know this because Neanderthal Y chromosomes and Neanderthal mitochondrial lineages are closer to considerably closer to Africans than they are to Denisovans. Even though if you look at all 3 billion base pairs, Denisovans and Neanderthals are clearly sister lineages, right? They separated over 500,000 years ago. They were from an earlier out of African migration now, out of African migrations feature large, you know, they feature in a lot of these narratives. And John Hawkes, the anthropologist Dr. John Hawkes of the University Wisconsin, wrote a paper 25 years ago, where he hypothesized that this was partly just, it wasn't an artifact, but it was a function of the demographic variation where large bodied apes are going to be denser on the ground in tropical areas during the Ice Age, when, you know, large parts of Eurasia are depopulated, due to expanding glaciers and tundra. And we do see this with Neanderthals. Their genetics are quite inbred quite bottlenecked. And so I think that this is broadly correct. The anthropologist physiologist, anatomist William Calvin, he wrote a bunch of books about human evolution back in the day, they're great books, but you know, I'm not gonna lie, human evolution before the rise of genomics, and definitely before ancient DNA was very, very speculative. And a lot of it was wrong. And there were way too many pages written based on very little data, okay, a lot of speculation, a lot of theory. I read those books, I read all of those books between 1990 and the year 2000. In my youth, I loved them. They were food for thought, but you know, looking back on it. I mean, I could have done something else with my time. I mean, it was entertaining. But you know, so is fiction, right? I'm not saying that they were fiction. But before we had ancient DNA, and some of the more powerful genomic methods, we could make a few broad course inferences. So for example, it's quite clear that Africans are the most genetically diverse, it seems likely that modern humans descend from a branch of Africans, and so forth. But all of the fine grained inferences that people were making about how people expanded how Africans are related to each other and all. A lot of it was very woolly. You know, and there are speculations so Calvin has speculations about back migration to Africa. You know, we had no ability statistically to detect any of that. People were using mitochondrial markers Y chromosomes later, you know, Spencer Wells, my former boss used Y chromosomes and that was fine. And then some people started using like, you know, like Templeton
the, the physical geneticist, Templeton, I forget his first name now, Alan, Alan Templeton had a model of out of Africa and again and again, but it wasn't using that Many Markers because we didn't have that many markers 25 years ago, now we have, you know, 90,000 genes, you know, 6 million Actually no, like, between six and like more than 6 million markers, okay, like about in an average human genome by like five to five to 6 million single nucleotide polymorphisms snips, you know, base pair substitutions, base pair differences, and then you have structural variants like indels, and all that other stuff. So it adds a lot more onto a lot, like, you know, fold more, but you know, considerably percentage more. So that's the variation we got to work with, which is just so much more than in the past. So where are we now, you know, I wanted to go back to three to 400,000 years ago. And this is not a DNA story. It is a story of morphology. So in Job elderhood, which is in Morocco, in the far northwest corner of Africa, there was a finding a skull, that looked kinda like a modern human, a proto modern human on the way to modern human. And so the morphology of, of this individual was kind of in between, or transitionary. So Chris Stringer, the Paleo anthropologist from England, I've talked to him multiple times about this. And, you know, he said, it's not really a modern human, but it's similar to modern humans. And this was a big deal, because the up until this point, the oldest modern human anatomically modern human was, I believe, almost rubbish in Ethiopia. And the dates for Omo kobish, around 200,000 years, right 200,000, maybe a little higher? Well, that is that's a good date, that mtDNA and the Y chromosomes are like, in that range, you know, the earliest mitochondrial DNA. And so mitochondrial DNA, for those who don't know is passed from mother to daughter, mother to daughter. So it's a direct line, there's no recombination, breaking apart the associations. So you have a situation where you can create a really, really elegant phylogeny. That's the word I would use very early on. And so that's what they did in the 1980s, with Rebecca Kahn, under Alan Wilson. And, you know, that was a big splash. And they they're kind of broadly right, there was a massive out of African migration. And the Y chromosome is the 1990s, something similar. You know, my former boss, Mr. Wells was involved in some of that the tail end of it at Stanford human published genetics laboratory. And they showed their same pattern, same pattern of much more diversity in African lineages and non Africans are a branch of Africans. So What's that telling us? 2025 30 years ago, it's just telling us that, you know, probably, parsimony was just that everybody outside of Africa descended from someone that left Africa and some population. Okay. So stylized fact. But, you know, it doesn't say much about the details here. Now, Darwin anticipated this, he believed modern humans would probably be from Africa. And his intuition was just like, look at the count of great apes. There's a bunch of great apes in Africa. There's a couple in Southeast Asia. So probably, you know, your priors should be some envy in some Bayesian world, that modern humans that humans come from Africa, that seems broadly true, not just modern humans, Neanderthals and denisovans seem to come from some sort of African lineage. And, you know, there were groups that move pretty early. Like I think, Domenici and Georgia went out like, almost 2 million years, you know, it was definitely more than a million years. So. And where did the hobbits and the Luzon people? Where did they come from? I mean, they probably came from Africa. Now we know, because most of the fossils are there. But you know, I'm not shocked that I'm not surprised that Ethiopia has the earliest clearly clearly clearly modern human because there is an immense amount of archaeology and paleontology, that's done in Ethiopia. And obviously, with the climate in the Rift Valley, there's some good conditions for preservation. You can imagine that archaeological work in the dense thickets of the Congo tropical jungle would not really, you know, work well. Now, in the past, some of those regions could have been Savanna during the peaks of the glacial maxima. It tended, the rainforests tended to fragment and so maybe we are from Congo, and we aren't from East Africa, we might never know, we probably will never know because those fossils are until we have like automata that are just scouring the whole planet. I don't think we can ever find them, you know, so there's some issue with just where you can find things and where the resources are. So this job elderhood in northwestern Morocco was really shocking, because it showed that modern morphology was present considerably before almost rubbish. It was, I mean, you know, the dating on Geobella hoods a little wonky, but it's definitely well, well, it's like 100,000 years before almost rubbish. It could be 200,000 years, but probably not. Probably, it's around like, you know, 75 to 100,000 years before almost rubbish, but I mean, think about 75 to 100,000 years long, it is longer than the presence of anatomically modern humans and most of Eurasia. Right. So it's a long time, it's a big gap. This resulted in a lot of arguments and discussions in the reemergence of something called African multi regionalism, I'm not gonna get into that detail. But the point is, there was a stylized fact that there was one tribe in East Africa that expanded and exploded, you know, 5060 70,000 years ago, according to mitochondrial Eve, it was 200. That turned out to be wrong. And they were confusing genetic genealogies looked at population demographics, and don't do that, you know, they can they can inform each other. But you know, they're not substitutes. Any case. That idea is not right, we kind of knew that even 10 to 20 years ago, but there wasn't enough data to have an alternative. So what it looks like today is within Africa, it's much more of a long fuse the transition of modernity. And, you know, there are individuals or populations 300,000, more than 300,000 years ago that are on the way to looking like us, but they're not quite us. And they're in various parts of Africa. And Africa has a lot of different human lineages, including the lady in South Southern Africa. Hey, hey, Lee, I know that you always complain that I leave in the lead yet I just don't know much about no lady come on the podcast, we talk about it. But um, so no lady is kind of like the Flores hobbits. It's small. It's got a tiny brain, but it seems to engage in a lot of modern behavior. And those of you interested in the lady, please listen to the podcast with John Hawkes. I talked about it extensively. So there's the lady probably there's stuff going on in West Africa, probably in the rainforests of the Congo, we just don't have the fossils. Again, the ladies in a cave in South Africa, there's a lot of people in South Africa, South Africa is the wealthiest country in Sub Saharan Africa unless you count like oil in Equatorial Guinea, which you shouldn't. And so okay, I'm not shocked that it's been found in South Africa. And there are people with ostrich cells and other things like symbolic behavior in South Africa, as early as I think 200,000 years ago, pretty early. So South Africa has been like, Ooh, it could be the birthplace of modern humans. But really, there is a new idea that there is no specific birthplace of modern humans in Africa, that humans emerged in some sort of modern humans in some sort of phyletic gradualism and interaction of different human lineages. So you know, there's Neanderthals and Denisovans. within Africa, there might have been a multiple different lineages. I know Aaron Ragsdale, I think he's at Arizona State, he has a very, very interesting statistical model. So he suggests that, basically, we are overestimating the depth of some of the phylogenies in Africa. And we are under estimating the gene flow between them. And so I want to put that out there, because there's still a lot of work to do most of the work in the next decade and understanding the human phylogeny. I mean, really, it has to be in Africa, it has to be ancient DNA, it has to be better statistical methods, it has to be testing and evaluating various alternative models against the data we have, right? So let's move to out of Africa, the people that left Africa, you know, Eurasians, Australasian people in the New World, et cetera, et cetera, everybody else. So I've talked to people, you know, I mean, I'll just named Rob David. David, right. You know, you guys missed most of you will recognize them. But not just David. Right. Others, you know, but you know, David told me, you know, and this other people have told me this, and I've kind of looked at some of the data. Actually, let me, I don't know if I should describe this, because it's better visually. But basically, there's a Bio Archive preprint that came out and thought of Alicia Martin's group at the Broad Institute, Dr. Alicia Martin. And, you know, Alicia has worked with 1000s genomes and the follow ups, and what her group and that sort of work shows is, you see the massive drop, I mean, it's not like two fold or anything like that. It's like 10%, or something drop in genetic variation outside of Africa. And you see non Africans are within a narrow band. So what you do in sort of these sorts of statistical genetic models, and any of these models is you have a bunch of different alternative demographic scenarios. And you see how they can generate the empirical data distribution that you have. So this drop, this uniform drop is an extremely strong tell of a strong bottleneck affecting everybody outside of Africa. Now, when people think of bottlenecks, they often want to think, oh, it's like a pinch of a couple generations. This is not what's going on. So one of the inferences that are coming out of a lot of these models, and they haven't been extensively explored for various reasons, I think it's just it's difficult in your DNA would help. And you can only like really explain
only so much with statistical inference to a really strong degree of certitude. So I don't think these models have really advanced much in the last decade. But basically, there is evidence that there was a very long bottleneck outside of Africa. And intuitively, the intuition I want to get across to you is, the length of a bottleneck is often much more important than the magnitude of a bottleneck. A long bottleneck means you have a population that's endogenously intermarrying, only with each other. And so you create a new population out of what might have been some somewhat different populations, right? So you can have like, this is true of Native Americans. And I'll get into that Native Americans have two very different ancestral populations, but they mixed together in a long long bottleneck phase, and they come out as Native Americans a relatively homogenous population. So the same thing happened to the ancestor on ancestry of non Africans. So every single human being whether it's a, you know, I'm gonna describe people here, because this is really confusing to people, black skinned, Melanesians, black skinned, Andaman Islanders, pink skinned Swedes, you know, Chinese people, Native Americans who've been here for 10s of 1000s of years, every single person from Ireland, to Tasmania, to Patagonia to China, all of their non what we call non archaic ancestry, all of their modern human African ancestry. The best models suggest they all go back to a tribe, or a set of tribes or set of clans that were intermarrying with each other somewhere within Africa, probably northeast Africa, or the Middle East. And these people like the, you know, your population estimate for how many there were vary, they go all the way from 100, which is kind of on the edge of, you know, probably inbreeding problems to 10,000, which is substantial. So I usually just say 1000. But if I, if you had to, like, pin me down on it, I think the census size, the headcount is probably closer to 10,000, the breeding population is gonna be considerably lower, because some people are not going to have kids in any generation, some are gonna have a lot more kids than other people and so forth, right. So this is not a big population. And they might have been isolated for 1000s, perhaps 10,000 years. I don't know what's going on. Nobody knows what's going on here. Imagine a scenario. This is just a thought experiment, where you have a group of Africans that are in the Nile Valley. And then there's a massive, massive, cold dry spell. So the Sahara was actually bigger, during the coldest, driest parts of the of the Ice Age, for various reasons. The northern fringes were actually a little wetter, as northern climates move south. But, you know, the, the Congo rainforest, which a lot of it's been burned down, but traditionally, it was like one expanse, it was actually extremely fragmented, do a lot of little, little fragments, because the expansion of the Sahara southward was incredible. And it was much drier and all that stuff, maybe as dry as today, because you can't get too much below point one millimeter. But my point here is the Sahara was bigger. So imagine that someone got some tribe, or group of tribes got isolated on the northern side, and it's between the Mediterranean and the Sahara. And maybe this persisted for like 5-10,000 years, I'd have to look at the parameter estimates, but 5-10,000 years of isolation, you get pretty genetically homogenous, you kind of look like Native Americans, like that's a natural experiment that we have. They seem to have been isolated in Beringia for on that order, like maybe 5000 years, maybe a little longer, but, you know, probably on the order of 5000 years, and they come out of it very homogenous and losing a lot of their genetic variation. So that seems to have happened. So I said Jebel Irhoud three to 400,000, maybe at the oldest, Omo Kibish, 200,000 lot of stuff going on in Africa, we don't really know enough about it. So I don't really want to talk about it too much. It's exciting. But you know, I'm not neglecting it. Because whatever. I'm just, we don't know as much about it as, as we do about what I'm gonna talk about now. Because it's a simpler model. So in Africa, you had multiple different modern human populations jostling and interacting and engaging with each other, you had a little bit of a population drop during the peak of some sort of ice age. So there are multiple warm phases. interglacials, and, you know, peaks in the Ice Age, when the sheets were really big. The most recent is the last glacial maximum, the ultimate Last Glacial Maximum about 20,000 years ago, but there were others. And you know, our lineages, lineage goes back more than a million years, almost 2 million years. So over this period, there was a lot of them. Okay. So you have a situation where you have one African population that's stranded, it gets genetically homogenous, this creates an extremely strong signal, right? So what's going on here about 60,000 years, I think is a good time. It's this population starts expanding. And this is not the first time that modern humans have done this. I just alluded earlier to admixture in Mongolian Neanderthals have something that looks kind of African. So that means that there are other moderns out there, right. And, you know, there's evidence from archaeology and whatnot of modern humans that are in Europe that disappear. So modern humans here means like African related humans that like pushed northward. And it looks like whenever the climate was warmer, African related humans move northward. And whenever it was colder, they move southward. Oh, like that's a big surprise, right? So this is like standard geography. Humans before the modern technological era are like animals and we move with the climate, we're adapted to the climate we're habituated to and where the, you know, big herds are or where the things that we can gather are. Okay. So you have initially Neanderthals and Shanidar Cave in Iraq, you know, they’re Neanderthals in the Middle Eastern Neanderthals in Turkey in Anatolia, Neanderthals in Iran. Some of them seem to have gotten into the Levant, but then they move backwards. So it's a back and forth, right. And there seems to have been a few times where African humans did go to Europe, interacted with the Neanderthals, and they kind of disappeared, they had some genetic impact on the Y chromosomes and the mitochondrial DNA. There's some issues with our models there, and they're wonky, but this is not about Neanderthals, and archaic humans. Okay, so All right. We have the situation where these proto modern humans are leaving their African homeland. All the other modern humans are in Africa, the vast majority of humanity, right 99% of humanity, who are related to us stem humans, anatomically modern humans, are there. Now I want to say something about anatomically modern humans are anatomically modern. Because they're related to us. They look like us. We define everything that looks like us kind of as modern. Well, that's not really true. So the way you do in phylogenetics and evolutionary biology, is their ancestral derived characteristics, drive characteristics are those that are different from the common ancestor. So if you have two species, and there's an ancestral characteristic, one of the individuals has one of the species has the ancestral characteristics, the other one has a mutation that emerged between the ancestor and the descendant. So for example, I think, Okay, I'm not a morphologist. This is I'm getting this from John Hawkes. You know, we tend to think of our jawline, as, you know, refined modern jawline, but actually, that's the ancestral human jawline. Neanderthals have a lot of adaptations that are derived and specialized. So we look at Neanderthal face, and we're like, ooga booga. Okay, but really, that's an adapted derived, advanced face. In some ways, we have our own adaptations, you know, we have our own derived characteristics, my only point here is to say that we are not more evolved in any way we are differently evolved, okay, all of us are differently evolved from our cousins, and you know, all these different human populations, right. So, you know, when I say modern humans, that's just kind of shortcut. Please don't assume that these are derived characteristics that we have necessarily. Perhaps we have ancestral characteristics that are very effective in some modern context. Who knows? Right? All right. So most of you know that people outside of Africa and actually now people inside of Africa because of Eurasia, back migration, have Neanderthal ancestry. Okay, that's great. Where did it happen? So the Neanderthal ancestry in modern humans looks very, very similar relatively, to Neanderthals that are found in Yugoslavia and not older Neanderthals that are found in Mongolia. That makes sense like these are European Neanderthals. Okay, so did we go to Europe and then spread to the rest of the world? No, I think what happened is, the admixture happened in the Middle East, because everybody pretty much has the same Neanderthal ancestry. They're from the same Neanderthals. So the most probable hypothesis is modern humans are expanding north and east of the Middle East and they absorb a clan of Neanderthals. Originally, the admixture percentage was larger than it is today, it's probably closer to 5%. Today, it's closer to 2%. And the drop is due to natural selection. There were some genetic incompatibilities. There's no evidence and modern human lineages of any sort of genetic incompatibilities the way you would do it is you would look at Eurasian and Bantu admixture and Khoisan and see if that admixture is enriched and over represented in non genic regions, regions, regions of the genome that do not code for genes and are not functional or underrepresented in the X chromosome because that region is exposed to natural selection. And also,
there's, there's some interactions between the x and other parts of the genome that tend to lead to hybrid incompatibilities, and I don't want to get into that. Okay, but Neanderthals, we do have Neanderthal ancestry. I have Neanderthal ancestry, but there were some incompatibilities like, so basically, what that's telling us is, incompatibilities in human lineages start to emerge sometime between 200,000 and 600-800,000 years ago, there's some weirdness of the parameter estimates of the divergence. So I'm going to give you the interval, but 600-800,000 probably covers it of when we separate it from Neanderthals, and then right after that Denisovans and Neanderthals have separated right from each other. But so modern humans absorbed these Neanderthals and they spread to all all corners of the world. So the Neanderthal ancestry in Papua, you know, in Australia and the new world, in Europe, in Asia. It's all the same Neanderthal ancestry. It's the same tribe. Now, there are individuals that admixture with local Neanderthals, but they don't seem to have left an impact. So there was a site in Romania called Oase. And that site, someone seems to have a Neanderthal great grandfather or great grand mother or whatever. But they had a Neanderthal within the last three to four to five generations in their lineage, right. And so that's different than the Neanderthals in the Middle East. Right. So isn't that telling you that there could have been multiple admixture events? Yeah, there were multiple admixture events, surely, but the issue is, there is no genetic descent from Oase in the first humans into modern Europeans, they all want to extinct. So that's that, that explains that, right? So the humans are spreading all across the world. But there is a model. And I think that this is probably true, but it's not necessarily true. So Laurent Excoffier in Switzerland, he and his researchers, they have like some really complicated, fascinating models that say that this is not necessary. I'm not going to go into that. I just want to note it and cite it. Some of this stuff is kind of cutting edge as it requires judgment on statistical issues that are - Yeah, they're not easy. Okay. Just keeping it real. Okay. But you know, the majority position, I think, is that there is a branch off of modern non African humans. So these are people that went through the same bottleneck that everybody else did. But they did not mix with Neanderthals. Okay, so what's going on here? So if you imagine that the modern humans are expanding in northeast Africa, and in the Middle East, they're going to mix with Neanderthals on their northeast fringe on the edge of the Northeast, right. So those populations are going into Europe into Asia. There, they mixed with Neanderthals, there could have been a group of modern humans that stayed anatomically modern humans that were also not sub Saharan African that stayed in, say, Egypt, North Africa, maybe parts of the Middle East, like, you know, Yemen, I don't know, okay, we don't really know, we don't know the details of what's happening here. Or it could be that the modern humans just exhibited a admixture with Neanderthals. So the - the tribes, the populations on that fringe on the border, in the northeast, in Turkey and Iran had Neanderthal admixture, the ones on the southeastern edge, maybe facing the Sahara, because it looks like we were isolated from Sub Saharan Africans for a while. Okay, so and I think that this is the Sahara that's, that's speaking, like, people can still cross the desert, by the way, and there still be no operational gene flow, you need one individual to move between demes - between two populations that are random mating. Sometimes the threshold is going to be like below one individual, which means that operationally, there's gonna be very little gene flow, the populations will diverge. So my point here is there could be contact across the Sahara, but operationally there's no gene flow. So it could be the what we call the Basal Eurasians, a group that split off first from the other non Africans. Maybe they split off more than 60,000 years ago or so. This population does not have Neanderthal ancestry is the theory. And basal Eurasian ancestry is like, depending on how you estimate it anywhere from like 15 to 40% of the ancestry of the early Anatolian farmers that settled Europe. So when you look at Neanderthal calculators, like 23andme has, you see a consistent pattern where Europeans have less Neanderthal ancestry than East Asians who have less Neanderthal and are and
Middle Easterners have less Neanderthal ancestry than Europeans, South Asians are in between Europeans and East Asians. So one hypothesis for this is that there is natural selection that's purifying the genome more strongly in these Western populations that have larger population sizes, larger population sizes, means natural selection is stronger, and genetic drift is weaker. I don't believe that. I think that the basal Eurasian hypothesis is plausible. So what happens is there's a migration of Basal Eurasians in western Eurasia, that it's expanding all over the place, you know, and it dropped the Neanderthal percentage East Asians show closer to what the Neanderthal percentage would have been before the arrival of basal Eurasian ancestry. And we do see this with Pleistocene and Mesolithic Europeans who did not have basal Eurasian ancestry, their admixture proportion of Neanderthals was about that of Asians - And so that indicates that there was a non Neanderthal admixed population in the Middle East at some point, a long, long time ago, 10s of 1000s of years ago, it looks like there are no Basal Eurasians in the recent, you know, like last 10 20,000 years, people have been looking, and they have not found any individual that's more than like, you know, 30 or 40%. So maybe this was, I don't know, 40,000 years ago, or whatever. But it was long enough time ago. The sample sizes are small, and we haven't found them. Eventually, we might but you know, we haven't. So I'm going to leave the basal Eurasian story there. So there's this first split of Basal Eurasians and it kind of had a big impacted later history, because Middle Eastern populations that had basal Eurasian ancestry due to agriculture spread all across western Eurasia, some of them spread in part to South Asia. So the amount of Neanderthal admixture South Asians have is in direct proportion to their West Eurasian ancestry, which drops it their Eastern Eurasian ancestry ancient ancestral South Indian increases it, all right. So we have a population of modern humans that are spreading all over the world, to give you some time points. And I'm not like a total expert on this, but I've looked at it closely. We know from ancient DNA by looking at ancient DNA Neanderthal admixture percentage, and also the way it's distributed across the genome, how many chops and cuts there have been in the genome from these Neanderthals, that the admixture happened about 55,000 years ago. And around this time, there's the Upper Paleolithic technology or the Upper Paleolithic, lithic toolkit or something, you know, they're newer and better weapons, maybe. And they're expanding all across the world. So we have an archaeological culture that's expanding, at the same time, that we have a strong suspicion now from genomics, that modern humans are expanding that the bearers of modern human genomic ancestry, right, flat faces, gracile builds, so we're lightly built, we have higher foreheads. We have this, you know, I would like to think an attractive chin, you know, but in any case, you know, no shade on Neanderthals or Denisovans, but heavyset, heavyset people, you know, so just keeping it real. In any case. So they're expanding all over the world. Some of them go through Iran, and they go to South Asia. These are the ancestors of, I'll call them Eastern Eurasians. But really, they're Eastern Eurasians, East Asians, Southeast Asians, Australasians, you know, a large ancestry of South Asians, the ancient ancestral South Asians, Andaman Islanders, and the majority ancestry in the new world, right. So these people, these modern humans are going to India, and they're pushing eastward. Last I checked, probably the latest that they show up in Australia is 45,000 years ago. All right. And so, you know, looking at the data that we have now, the Australian aborigines are possibly one of the groups that's descended from the first settlers. There might have been earlier modern pushes that went extinct. I don't know, I don't really believe those those sites in Western Australia, but there are some okay. And I do believe that some of those are real, at some point somewhere in Eastern Eurasia. Okay. Because we know from genetically that they mixed with Neanderthals, there are people there that were African, Neo African, proto modern humans, but any given site, I'm kind of skeptical of - and the Australian ones I am, in any case, us humans are in Australia by 50,000 years ago, probably probably 45 to 50,000 years ago, modern humans, and they show up, there's these giant wombats, giant kangaroos and all this crazy stuff. And most of those animals disappear immediately. So this is like, you know, the Australian blitzkrieg. They don't necessarily disappear immediately. But I mean, they're gone pretty soon. So what happens is, you know, it's like, it's like money in the bank account. And it's not like humans exterminate everything, but animals have ups and downs, there's climatic changes, there's epidemics. And when the money in your bank account is low, you overdraft overdraft, and they close your bank account. So humans just drive animals extinct because they add a new pressure. And that's just too much because they've been in equilibrium. You know, balance with nature for millions of years. When we show up, we throw the balance, you know, like, all everything is, is thrown out of kilter. So we show up and, you know, in Australia, humans did a lot of firing. They reshaped they changed the landscape. So it's much better for certain types of medium and small kangaroos and koalas. So the Australian animals that we see that were really numerous when Europeans show up they’re partly - I mean, there was a giant platypus, right, there was a, there was like a two or three foot platypus or something? Like a big platypus. They probably just ate them.
I mean, it’s like, you know, delicious platypi. I don't know. But anyway, all the platypuses do have like, you know, they have poison, but my only point here is modern humans show up. They break the Wallacea barriers - so Wallacea is the transition between Asia and Australasia, popla. In Australia, and at the time, remember, Papa and Australia were Sahul they were one continent. The base of the Thailand was Savannah that was Sundaland. I did a podcast with Spencer. I did several podcasts with Spencer Wells, about Southeast Asia. He's in Southeast Asia right now we both have an interest in Southeast Asia. So check out some of the old archives of the Insight if you want. There's some stuff in there and it's all topical. In any case. Yeah, so I mean, humans are there, but 45,000 years ago, what's going on in Europe, Europe is a little different. So one of the weird things about Europe is it looks like humans, modern humans, anatomically modern humans took a little longer in Europe to have absolute domination than it did in Australia and why? The reason is in Europe, I think it's because there were humans that were already there - they're called Neanderthals are very well adapted. And Australia just had giant platypi. You know, so it was like, it was great in Australia. Okay, so Neanderthals, it used to be that there were some sites that were supposedly active in. Was it like the last Neanderthals were probably in southern, it was in Granada, in Gibraltar. So basically, that's the end, that's the Lands End, that's the end of Europe, I wrote a couple of substack posts, by the way, that kind of well, actually, I wrote a bunch of things that relate to this, like geographic aspect of Europe, where it's like, you know, the southwest corner is where everything ends, because very little goes across Gibraltar until modern, not modern, but you know, better sailing vessels, better boats, I'm sure that there was some migration across and someone floated across, but just wasn't common enough. It looks like the Neanderthals that are in Europe, you know, they're coming from the east, modern humans are coming from the east, people are not crossing Gibraltar and vice versa. There were people on the other side, but you know, they should have been able to see their fires, they should have been able to see, but they didn't have much contact, right. So it used to be that they used to say, Oh, 30,000 years, but now I think it's like closer to 40, maybe a little earlier, basically, there was a rapid transition over several 1000 years, as modern humans start expanding. And this has happened before modern humans like, you know, kind of put their toes in the water and, and try to make a go of it and kind of always failed, you know, the last like earlier 50,000 years or whatever, probably earlier too - I mean, there was some genetic admixture. And anyway, that's a different different podcast. But in general Neanderthals held their own this time, they didn't hold their own. They were just, you know, we swept them, you know, there was a three game sweep or whatever, it was bad or four games, it'd be a four game sweep four game sweep, right? If it was like seven games. So, you know, we admixed with them, we have some of their genomes, it looks like there might have been some adaptation of Neanderthal cultures in the Châtelperronian culture in like modern day France has Neanderthal culture that integrated some modern human advances. Now, the issue with modern humans is it looks like we had better, better clothing, we could operate beyond the woodlands in the tundra. So we think of Neanderthals as cold adapted, and they are physically cold adapted, in terms of just their noses, probably like heated the air that they breathe in stocky, build, robust, you know, et cetera, et cetera. But we had really good technology, we have really good clothes. I'm actually gonna do a podcast with Virginia Postrel. And we will be talking a little bit about textiles. So you know, fabric of civilization, all that stuff. So, if there was a big deal, I think we had various types of bone needles. It seems that humans have had bows, bows and arrows and lost them and atlatl multiple times. There's some evidence, I think, from the archeology of bows as early as 46,000 or so years ago. So Neanderthals seem to have had just mostly thrusting spears. Now, they probably adopted some of our technology, but for whatever reason, they weren't the most innovative even though they did do art and other things. The question about whether Neanderthals or human I think they clearly are human. I have Neanderthal ancestry, most of the people listening, actually all of the people listening have Neanderthal ancestry. And arguably all humans do because we know the Khoisan, have Eurasian ancestry, and Mabuchi pygmies have some West African ancestry. And West Africans have some Eurasian ancestry, etc, etc. And we all be Neanderthals, right? But different degrees, so I'm about 2%, European listeners are like 1.8%, or whatever, and East Asians are like 2.1%, or whatever, you know, okay. So they're human, they're just somewhat different. They're different enough that there's genetic incompatibilities, and they just couldn't adapt to our cultural, you know, creativity, whatever it was, right. Okay, so we swept them from Europe. And there are these people, various European Pleistocene cultures. You know, sometimes we call them Cro-Magnons, or Cro-Magnon, you know, but I don't think the archaeologist don't call them that anymore. Their culture is like Aurignacian first, and then Gravettian , and then I think, like, Solutrean, and then Magdalenian. And then eventually, at the end of the Ice Age, the Epigravettian there's a couple of others that I'm not naming. These have all been studied and catalogued, because there's so many archaeologists in Europe, Europe is cold. So it's preserved a lot of things. We know a lot more about Europe than anywhere else, obviously. Right. So I made a bet with Chris Stringer, many years ago, mid teens, that ancient DNA would show massive disruption in Europe, of genetics, from the Ice Age to the present. And I was right. So the first the first Aurignacian cultures, archaeologically, that show up, they didn't leave any descendants. They are not more related to East Asians, to Europeans to Middle Easterners to Africans, they just they ended right. So they're part of like an expansion out of the Middle East really early on and they just ended. The second group like related to the Gravettians, they left some heritage down to the present but not very much. And then the Magdalenian ones, also similar. These are the people that did the caves and Altamira you know, beautiful caves and some of these movies you see. So you know, they're hardcore creatives. Definitely modern humans, like no doubt about it. But they were replaced by, you know, the ancestors of Mesolithic Europeans, genetically have called the Villabruna cluster. But you can also see they’re Epigravettian I think - they have some connections to earlier populations. But I think the easiest way to explain is modern Europeans have, you know, maybe like a percent or two at most direct continuity with people that lived in the continent more than do the math 16 or 17,000 years ago, right. So there's a little continuity. But you know, it was basically hunter gatherers absorbing other hunter gatherers, sometimes there are exterminations. But this is actually recapitulate what happened with the Neanderthals. And so I have a hypothesis, which I've presented on my podcast about China, that, you know, Europe is just really hard to have continuity, and because when it gets cold and dry, it drives everyone into these little pockets. There's mass exterminations, or, you know, mass extinctions not extermination, because no one's killing each other. They're just dying, and they have to be repopulated from more populous areas, which is the Middle East. Now, if the Sahara did not exist, I think you would see massive repopulation from Africa over and over again. But the existence of the Sahara protected Eurasians, to some extent, from the demographic wave, because they're just more Sub Saharan Africans. You know, the Ice Age, would result in the increase of Savanna territory, a savanna habitat in much of Sub Saharan Africa, which is arguably better human habitat than the rainforest. There is some anthropological arguments that the rainforest pygmies cannot exist without agriculturalists in a symbiosis. So they do things for the agriculturalists. They supplement, they supplement their diet nutritionally, it may be that the deep rainforest could never be occupied by humans, because it just you can't get enough protein - thing is a you know, yeah, there's a lot of life in the deep rainforest. But a lot of it's inedible to us, like, you know, there's various vegetable type things they're not, you know, young, you know, like, imagine eating a fern, okay. And then the other thing is, you know, there's a lot of bugs, there's a lot of like small animals, those animals require calories to capture. Because they're scrambling all over the place, what you really want is a big elephant that you kill that goes down. And that's just like a big pile of calories, and you don't have to do anything. There's a lot less of that, like there are some rainforest elephants, but there's a lot less in the megafauna than in the savanna where we can capture really easily so could be that rainforest place Humans are a product of the last, you know, 10,000 years in the Amazon, just jumping ahead. I'm not gonna talk about this, but Napoleon Chagnon in “Fierce People” in his documentaries in his books, of the Yanomamo- They were not hunter gatherers, they were not hunter gatherer foragers. They were slash and burn agriculturalists that lived in the rainforests. So it could be that pure, pure hunter gatherers have a difficult time in these rainforests. Andaman Islands are kind of rainforest, and they are pure hunter gatherers. They're the only ones really, outside of the Khoisan and the Mbuti who are continuous and have never shifted back and forth, because a lot of the hunter gatherers in other parts of the world probably went through phases, maybe the ones in Siberia never did, in terms of they just engaged in foraging and gathering. But in the tropics, most of the foragers and gatherers, at some point were farmers, and maybe they ran off this happened in places like Burma and the Philippines that we know about, you know, and it's an attractive lifestyle, if you can make a go of it. I mean, we saw this in the American,
you know, Frontier, people would go native all the time, and Native Americans had agriculture, but they also engaged in some foraging and, you know, nomadic lifestyle that, you know, a lot of people liked that stuff. They don't want to be on the farm all day. But in any case, so Europe had these multiple waves of modern humans show up. And the last wave is the Villabruna. They're the Mesolithic Europeans. They're the, you know, Western hunter gatherers and stuff like that, that, you know, those of you who follow the ancient DNA and a lot of you I know a lot of you do know all about right? know and love, but what's going on in East Asia. So I want to I want to talk about East Asia, Southeast Asia, and go back to this, this migration through Iran, down into the Indian subcontinent. So this is when humans started mixing with Denisovans. So it looks like it looks like Denisovans split into multiple populations that multiple human populations are mixed with. So the way you do this is you compare the segments, you compare the genes, you compare the genetic signatures in the Mongolian Denisovans, which have good genomes with Denisovan ancestry in other human populations. Because it turns out, you know, like, if you're using a Mongolian reference with a Papuan person, those Denisovans were totally different. And so the match is going to be different. And it's going to show lower. I don't know if the term is fidelity, but identity than it doesn't East Asians, so it looks like the Denisovan- So Chinese have about .1-.2%, that's really low. But whatever, we have whole genomes, we can compare Denisovan ancestry, that Denisovan ancestry is very similar to the Altai Denisovans. Okay, the Papuans have about 5%. And those Denisovans do not look very similar to the Altai Denisovans, at all, you know, and that's how I'm getting these estimates of like 300,000 year separation, right? So it looks like there are multiple Denisovan populations. And it looks like the Papuans might have have one to two admixtures with Denisovans. This may be that there were Denisovans in India, and this is the first admixture. So Indians have Denisovan ancestry, it's a little bit more than the Chinese actually. And it's correlated with your ancient ancestral South Indian ancestry. So, if you are a South Indian, you have more Denisovan than if you're North Indian. And if you're Northwest Indian, you have less Denisovan than if you are any other type of Indian. If you are in your Indian lower on the caste hierarchy, you will have more Denisovan because you have more ancient ancestral South Indian usually, whereas if you're higher up, you have more steppe ancestry. You have more Iranian, Eastern Iranian paleo Iranian ancestry that has no Denisovan there was no Denisovan ancestry. It looks like west of India, right? So you go into Southeast Asia, there's different types of Denisovan ancestry, the highest Denisovan ancestry today is in Papuans but the Denisovan ancestry in the indigenous Negrito people of the Philippines so the Aeta is the one that I can remember Aeta but um, these people, they're about like two thirds, Austronesian and 1/3. So there's multiple different types of Negritos in Southeast Asia. So the Andaman Islanders, there's peoples in the interior Malaysia, one group in southern Thailand. And then you have the ones in the Philippines. The ones in the Philippines are very distinct because they're distant, but they are much more closely related to people and Papua to Melanesians, than they are to the Negritos in Malaysia, or the Andaman Islands, they than they are probably to the Negritos that were on the mainland. They weren't Negritos then. They were just like dark skinned foragers that were there when the farmers came from the north from China, right? So these people, their Denisovan percentage is pretty high. And if you estimate that it's all from their indigenous ancestry, they have the high you know, the non Australasian ancestry, they have the highest Denisovan fractions like higher than Papuans. And it's a different again, it looks to be a different type of Denisovan than the Papuan admixture there was a Philippine Denisovan of sorts, I guess. So, you know, the story of the modern human conquest of East Eurasia is mixture with multiple different type of human populations that were there. It seems like they were all Denisovans maybe there was some admixture with the Flores hobbits or something else. I don't know. I don't know how that would work Anatomically - I think it was probably phylogenetically too distinct. I mean, honestly, I wouldn't be surprised if early humans thought hobbits were monkeys and just ate them. You know, they seem to have disappeared, right about during this wave expansion of modern humans. So the modern humans in Southeast Asia at this time, are much more like the ancient, you know, ancestral South Indians than they are like modern Southeast Asians were about 75 to 85%, descended from people that pushed out of southern China, southern South of the Yangtze River Valley, and brought rice agriculture. And I'll get to that, I'll get to that. The story will, will get a little bit to that, although I talked about that extensively in the China podcast. So listen to that, if you really want to know in detail. So you know, in East Eurasia, you have multiple populations. It's not totally clear what's going on, but it looks like there's two branches, one North one south, and these branches separated. You know, really early like 50,000, separated right after the separation from the west Eurasians. They're going out of Iran going into South Asia. One branch moves north, one branch stays south. So Australians and Papuans are a little bit closer to the people in India, and the Negritos of Southeast Asia the Andamanese than they are to Han Chinese and whatnot. These are all part of this big east Eurasian lineage that split apart as it went eastward. They split apart well before 40,000 years, probably between 40 and 50,000 years Australians show up 45,000 years ago. That means They split up before 45,000 years ago, right? But there's structure there's genetic variation, there's drift that's emerging. Some of it might be due to local admixture with Denisovans. But really, that's not enough. Not enough of the genetics, right? So probably what's happening is there's differentiation as you're going east into different streams that are different tribes that have different cultures. And you had like the first big break is between northern and southern East Eurasians. Okay. But there's a twist on this. And the twist is, there's a lot of circumstantial evidence that's pretty strong now, of modern South American indigenous people, as well as one ancient skull from Brazil, that there was a stream of people from the old world that went into the new world, went into North America and South America, early on, that are more related to the southern East Asians that are more related to people in the Andaman Islands, to Australian Aboriginals, etc, etc, than they are to the Han Chinese or people in Siberia. So what's going on here? Right now, today, we tend to think of these as Northern and Southern branches. But what if the differentiation happened in Southeast Asia? And it just worked out that, you know, in the north, all of the Northern branches, quote, unquote, won out and the southern branches went extinct in the south vice versa, right. But it could be that there was some population that was more close to Andamanese that went into Siberia, right? We don't know. We don't know what's going on here. This is like a really different time. The world is mostly empty. There's the really, really low density archaic, Eurasian hominins. I'm gonna use the word archaic, I think it's like a pejorative word, but I'm gonna use it, you know what I'm saying. And so I think it could be that either these people were integrated into the early Beringians or they came earlier. There's a lot of evidence now, of people in the new world before 20,000 years ago, before the Beringians could be that these people, they were not very good hunters, or they were just strictly maritime hunters. And so they didn't like it doesn't look like the local fauna went extinct, as you would expect. If if, you know really intense hunters were there. So
East Eurasia is split apart pretty early. So you have Chad noon man in Beijing. That dates to 41,000 years ago, I think. And that individual is a little bit closer, I think. I mean, I've seen different phylogenetic trees, but my understanding is a little he's a little bit closer. He's a man, it's male Y chromosome to modern northeast Asians than se like the indigenous Southeast Asian like Negritos, Andaman ease these people, Australo-Melanesians. That's another way you can say that. Although that's a different branch Australians and Papuans, they separate it pretty early, actually. So their genetic that you can tell genetically, they're closer to Andamanese people than they are to Han Chinese is interesting, because that means that the splits were far enough in the past that is still discernible, it could be that the Han Chinese just have something else that's making them distinct. I don't know, these statistical models, there's alternative models that can explain them. And you need more and more ancient DNA to really resolve to basically have like three different models and you want to resolve it down to one. Well, you need to reduce like the parameter space in various ways. There's like fix the parameters by using ancient DNA because it's like, oh, this is obviously not a scenario that was real. So you eliminate that scenario, like that condition cannot hold, right. So in East Asia, you have the situation of early diversification, and kind of like the sinking down to roots of these northern and southern lineages. Now, in Siberia, you have a really different situation. An Interesting situation. This is kind of a little bit more like Europe. So in East Asia, as I said, the China podcast, modern Chinese seem to kind of descend from unlike Europeans, they descend from the people that showed up around 40,000 years ago. Now, I know, there's some papers that show like differences up until about 30 20,000 years ago, Tianyuan man, people went extinct. But really, from what I can tell, like looking at the papers closely, it's just that there was a lot of different populations descended from these early settlers. we've sampled some of them in the ancestors of modern Chinese or from others, we haven't sampled, but they're all part of the same group of populations. In Southeast Asia, you had these, you know, dark skinned people. I'm not gonna call them Negritos because they're not tiny, because they don't live on islands. Island, people tend to start shrinking and these are calorie needs. They were not Negritos they were more like Melanesians they were dark skinned people. And, you know, there’s diversity of them. So they didn't all look like Andaman Islanders, but they were dark skinned people. And they were descended. They were closely more closely related northeast Asians, right. And that was like that up until about 4000 5000 years ago. And then you have a situation where the northwest of the Indian subcontinent, you have all these West Eurasians pouring in like well before the steppe people, you have the Iranian people Bringing wheat and agriculture and also pastoralism. These people are from Afghanistan, Eastern Iran, they've been there for a long time since the Pleistocene. It's not due to the Zagros migration, it seems to be somewhat more localized to that region, right to the northwest. And then in Southeast Asia, you have an expansion out of southern China Austroasiatic people to the Yangtze River, apparently, it's originally the cognate for it is from Krong, which is an Austroasiatic word. And then the Thai Credai languages and the Austronesian languages from Taiwan are expanding southward. So today, many of these languages are found in China, but they're, they're far diminished. And they're far south of maybe where they originally were. And they're dominant in Southeast Asia. So that demography that ethnography, that linguistic and genetic landscape has totally transformed. But you know, at the end of the last Ice Age, the original status quo I think, that occurred around 40,000 30,000 years ago, still held right. Okay, what's going on in the Middle East, what's going on in Europe. Now, I told you the succession of these cultures in Europe. I think most of you know the story of Europe. So I'm going to go through it really quickly, because I've talked about it in my indo European podcast and my writings and whatnot. What happened is you had farmers come out of Anatolia, and they mostly replace the native European hunter gatherers in the west and the east. There's big physical difference between the two groups. native European hunter gatherers have dark skin, maybe not black skin likes depicted, I think, more like some brown skinned Native American type people. Honestly, if I had to bet, but they have blue eyes, they seem to have blue eyes. And the farmers are lighter skinned, more like modern Middle Eastern people in coloring and complexion and dark eyed. And the two groups mixed eventually, after an initial period of segregation in some places, the replacement was pretty intense, actually. But in Northern Europe, there was more admixture and amalgamation to the point where some of the y chromosomal lineages that are dominant in Neolithic farmers societies later on, are clearly from hunter gatherer. So the haplogroup I is a native European one I1 I2 - I1 is dominant in Sweden today and much Scandinavia. I2, mostly in the Balkans, but among the people. You know, among the late Neolithic populations in Central Europe, I2 was a very dominant haplogroup, and I think in among the elite lineage in Neolithic Ireland that Lera Cassidy is worked on. I mean, that was I2 as well. So she was integration between hunter gatherers and farmers. And there's some stray individuals that are late pure hunter gatherers. I don't know maybe, like 5000 6000 years ago, but they're stray late hunter gatherers. That means, there's pockets of hunter gatherers that lasted pretty late. And they probably looked very different than the farmers like dark skinned, you know, blue eyed, whatever, like kind of like, and also their features are going to be coarser, because if you don't eat like kind of the gruel that farmers eat, you're just not as gracile like your jaws are bigger and stronger and more powerful because you've just been chewing the tough food, right? Okay, so that's what's going on in Europe with the farmers. Eventually, they're overwhelmed in the north by steppe herders who also have an impact on the south. And so that's the story there. I think most of you know that story. What's going on in Siberia is interesting. So most of you know some of you know about a group called Ancient North Eurasians. Sometimes they're also called paleo Siberians. These people seem to have split off from people in the Middle East and Eastern Europe about 40,000 years ago, so a long time ago, just as people were differentiating and East Eurasia, people differentiate in West Eurasia. And these paleo Siberians they went to Lake Baikal they went to northeast Siberia and the Arctic coast, they pushed deep into Siberia. So this is a situation where modern humans totally destroyed the precedent of the Neanderthals. Neanderthals didn't go deep into Siberia, because they had to operate in woodlands they had short thrusting spears, they were just not good. They were not extreme survivors. We’re extreme survivors, so we pushed really far. This is also where the dog was almost certainly domesticated the earliest dogs, probably domesticated by the Paleo Siberians by the ancient North Eurasians. The dog myths that span indo Europeans to Native Americans probably date to the paleo, Paleo Siberians in ancient North Eurasians. And, you know, just to cut to the chase, jump ahead, about 30 to 40% of the ancestry of modern Native Americans is paleo Siberian is ancient North Eurasian, that means it's genetically closer in some distant sense to Europeans, that element of their ancestry. And that's why the early statistics and phenotypic analysis of Native Americans were a little off because they don't totally look like East Asians. Now, 50,60, 70% of their ancestry is East Asian. They call it you know, you can call it is some sort of Siberian, okay. It's not quite Manchurian or North Chinese at all. It's something that's split off earlier because they separated more than 20,000 years ago. It seems like they got stuck in this Some sort of high latitude tundra in what is now the Bering Sea. It was Beringia. And they were shut off by ice sheets to the west and ice sheets to the east. And they were just stuck there for 1000s and 1000s of years, maybe like 5000 years or something. So they created a new society. That's a mix of paleo Siberian ancient North Eurasian, along with Siberians that are pushing up from modern day Manchuria, that area right. So these people the Manchurians these early, what's called them Neo Siberians. Oh, there's another. There's multiple waves in Siberia. I think it's because it's cold. It's hard to live there. And people just die off all the time. So I'm not going to get into that but Native Americans mixed between these two groups. So haplogroup Q, which is dominant in Native Americans, probably from paleo Siberians. By the way, these two groups mixed, it became like one population, they moved into the new world. There may have been, you know, some sort of earlier East Eurasian population there. I don't know, we don't know what's going on there. But there's just enough evidence that there's stuff going on now. That I we can't dismiss it, right. So
you know, they expand all the way to Patagonia. And so now we have humans that are in the interior, North America and South America, not just on the coast, maybe, you know, and they're big game hunters. And that's the story. That's the conquest of the Americas right. Meanwhile, back in Siberia, you have multiple waves of admixture. So modern Siberians, as far east as the Urals, they're more East Asian, they're more East Eurasian than their ancestors were. So the Paleo Siberians mixed with people in Eastern Europe, they mixed with people on the edge of the Middle East, they mix with people in Northwest India, they mix with everybody, they mix themselves out of existence. So there's a little bit of paleo Siberian ancestry across Siberia a lot in some populations. So among the Ket in central Siberia, a lot of it and paleo Siberia is mixed with East Asians. So the two groups exchange genes. So early paleo Siberia seemed to have some East Asian ancestry, you know, Gene flow out of the south, this was where the two great streams of western and eastern Eurasians merged back together in Siberia, you know, after 10s of 1000s of years, or over 10,000 years, whatever. So, these populations did not exist in pure form. The last of them are actually the famous beauty of Loulan, the Tarim mummies, these are people with the highest ancient North Eurasian ancestry at the latest state. So they did exist, it seems in pockets in Siberia until relatively late, but they were overwhelmed by an expansion of East Eurasian people. And I think this is again, a simple, I don't know hydraulic, thermodynamic type of argument where population just started increasing a lot in East Asia, East Asia is closer and easier access to Siberia than Europe or the Middle East, or South Asia. So Siberia became East Asian. And I have written extensively about this Y chromosome. I think the old the old taxonomy Was N1c I think it might be N3 now. But there are Siberian Y chromosome, paternal lineages that spread westward that are in Finland, that are dominant Latvia, Estonia and Lithuania, that replaced the local r1a lineages that were dominant in that place in those places. And now, you know, in Estonia, and Finland, they speak a Finnic language, you have the Sami and the north, the Sami seemed to have admixed with local hunter gatherers that had been relatively untouched. These are not Western hunter gatherers. There's something more like Eastern, I think. So you have a lot of stuff going on to the north, there was a recent Viking paper and I will probably do a substack on it. Stay tuned. I will do one. Yeah, I will do it. But in any case, that showed someone as late as like 2000 years ago that looked like could be mostly a European hunter gatherer of some sort that didn't have any farmer ancestry, or steppe ancestry. That indicates that there were pockets in the north of the East that lasted quietly, which is not shocking, because with archaeology and ancient DNA, your first and last hits are almost certainly not the real first and last hits, you know, like you're getting a sampling of the distribution. And it's going to be, you know, kind of more towards the median, more towards when that ancestry profile is much more common. All right. So I've already touched on the New World, which was actually my kind of like, I wanted to hit the New World, I want to emphasize the big bottleneck, and then like the rapid expansion, so some of people will ask me, you know, we look, you know, people outside of Africa look really different from each other people in Melanesia. They don't look like people in Africa, but they have dark skins, they have curly hair. What's up with that? Are you sure they're not? They're not African? Yeah, they're not. They just, maybe that's what we all originally looked like. And we diversified and changed, you know, but you look at their genetics, and they are no closer to an African than a person from Sweden is And in fact, they're a little closer, a little more distant, mostly due to genetic drift because they went through more bottlenecks. You know, it depends on whether you want to count that as real or not. You know, there's statistics that correct for the drift parameter that the drift amplification this long branching, and others do not. So all non Africans are equally related to, you know, the ancestral African type. Now here the issue is, it looks like there's like low levels of back to African migration periodically. So this stylized differentiation with African and non African is a little of a first order approximation. There are some genetic models that show gene flow between Africans and West Eurasians. That might explain some patterns that we see. So there's still some uncertainty. And the narrative that I told you might not be totally true. I think it's mostly true, but there's going to be aspects of it that are false. You have a situation where within Africa, there's been massive changes in the last 5000 years. Everyone keeps asking me the Bantu expansion. Am I gonna write about it? Yeah, I'm gonna write about it. It's a big deal. It totally transformed eastern South Africa, Central Africa, over the last while, basically between 1000 BCE and 1000 ad, right, everything changed. So during the time of ancient Egypt, Kenya, and all that area was totally different in terms of who occupied it. There was a bunch of foragers. And also, like some pastoral, early pastoralists, maybe, but no Bantu farmers, right. That was later that was later. And so Africa totally transformed relatively recently, prehistoric Africa was very different than modern Africa. And modern Africa has been hit by Eurasia and back migration. Some of it we knew the Ethiopians are quite clearly about 40%. Arabian like, but you know, their stuff in Nigeria. So if you use the 1000 genomes, if you use the HapMap use the Yoruba or the you know, these Nigerian populations. You don't use Hausa, because hos are known to have Eurasian ancestry, but you can use Yoruba, that's a common one. I think there's, there's not Igbo I think it's Iban or something. In any case, they have low levels of Eurasian ancestry, though it's quite clear they have a little bit of Neanderthal, there's something going on there. So that's not a perfect sample, it's not a perfect proxy, what you probably want to use is, you know, the Barito Boy Khoisan sample from like two or 3000 years ago, something like that. All of the a lot of these ancient African pop samples are quite different than modern ones, because they don't have Eurasian contact Eurasian ancestry. In terms of conquest of the world. One thing that's happened during the agricultural period during the Holocene is the world has shrunk genetically, population junk distances have shrunk all across the world, mostly, I think, because of denser populations, more trade more networks, so everyone's more connected to everyone else, then it was true like 10, 20, 30,000 years ago, the genetic difference between farmers and agricultural and foragers in Germany 7000 years ago, when they were not intermarrying they were occupying different areas is the genetic difference between Chinese and Northern Europeans today. And it was like that for 2000 years, this is as great or more of a difference than it's actually greater than the difference most of the Indian caste system even so, the caste system is pretty weirdly stratified from a modern perspective. So, you know, in some ways, the past was a different territory, a different land. So I think in the broad sketches I have, I've told you guys what's going on. And I think things are clearer than they were, I think we had false certitude. We had false clarity. I think we have true clarity now. Now that clarity it still has big holes. Probably the biggest hole is like what's going on with the Neanderthal replacement of Y and mtDNA? And why is there no strong autosomal signature genome wide? David Reich has admitted maybe there's something deeply wrong with our models and our presuppositions. Maybe everything is flipped upside down, I don't know, there could still be something like that, there's always a chance and you need to keep an open mind. These are models and ancient DNA has transformed everything, because the way it works is you have a phylogenetic model and ancient DNA samples within the phylogeny and it allows you to eliminate so many different alternatives. Right? So what was pretty much an intractable problem, which was theory and wish, wishful thinking has now become the real ability to answer questions that are posed and to actually understand the demographics of the human past. And the last couple of 100,000 years have been like pretty weird, as, you know, our own stem modern African human lineage, you know, whatever you want to call it has, I think it's pretty much extirpated and eliminated all the other big human populations. We absorb some of them. There are more Neanderthal genes around today than there were in the past, although only 1/3 of the Neanderthal genome came down to the present, a lot of it was just like, eliminated early on, I think, during the admixture process, and that's one of the things that I think people are gonna have to look at. Anyway, if you're interested in this sort of topic, again, check out my substack razib.substack.com Some of the stuff is free, some of the stuff is paid. I have written extensively about all of these things that I've talked about, but you know, writing can be a little abstruse and you know, things are here things are there. You know, I've tried to put into this conversation or not the conversation, you know, Song of Myself, you know, it’s a conversation with myself though, you know, I have all the big things that I've known of what I know you know and I hope that that's helped you guys. So with that I will end this podcast and I will talk to you guys next week. Thank you very much
Is this podcast for kids? This is my favorite podcast.
