Human Origins: Did We Begin in Africa?

0:00Ever wondered why the Romans were defeated in the Chutaburg forest? What secrets lie buried in prehistoric Ireland? Or what made Alexander truly great? With a subscription to History Hit, you can explore our ancient past alongside the world's leading historians and archaeologists. You'll also unlock hundreds of hours of original documentaries with a brand new release every single week covering everything from the ancient world to World War II. Just visit historyhit.com-subscribe. The story of modern human origins is often imagined as a simple journey out of Africa. Homo sapiens emerging somewhere on that continent before spreading across the world and replacing other forms of human life. But how is that story still evolving? Is the full truth of our beginnings actually much more complex? Over recent decades, evidence in the form of fossils, improved dating and ancient DNA have transformed the traditional picture, revealing a deeper, much messier tale of shifting

1:05African populations, multiple migrations and sister species like Neanderthals. I'm Tristan Hughes, this is the ancients, and today I'm joined once again by leading paleoanthropologist Professor Chris Stringer to explore what the out of Africa theory really means today. Why it still matters? And what exciting new discoveries could still be revealed about where we come from? Chris, it is such a pleasure to see you again, welcome to our new studio. Yeah, it's great to be here, it looks great. And well we couldn't think of anyone better to come on the show to talk about human evolution and our story and the fact that Africa was and still is, I guess, the mothership for our species. Yes, it still is the main place, but obviously the more we learn about some of these

2:08other places, particularly places like China, we realised that they're an important part of the story too. And I guess it's as we delve into, there's going to be quite a sciencey chat and how that the out of Africa theory, it has developed a lot over the decades, hasn't it? Yes, I mean, since even the 1970s and early 1980s, when I and a few others were proposing this, very much a minority view then, it was a very simple version that we had based on really slender evidence and it's developed so much now, particularly obviously with the DNA evidence, but also new fossil discoveries and new methods of dating things. And so for how long then has this idea, this proposal, that, you know, Homo sapiens originated from Africa, how long has that been around? Well, I and a few others started to tentatively propose it in the early 1980s. 1980s. And it was based then just on the fossil evidence, but, you know, there was so much we didn't know, there was so much uncertainty that it was put forward very cautiously.

3:12And then in 1987, of course, we had the story of mitochondrial eve appearing, which argued purely from recent DNA evidence, mitochondria, mitochondrial DNA inherited only through women, it argued that everyone in the world today could trace back their ancestry to a woman who lived in Africa maybe 200,000 years ago. And this was based purely on data from present age humans, but it matched obviously very well with what some of us were saying. It gave an even clearer and apparently more confident picture that we had a recent African origin. And it was very important to ask that because I was wondering if anyone had, like, potentially put forwards that theory before the 1970s and the 1980s, but it does sound like that was actually where it really is. Yeah, that was the beginning. I mean, people like Bill Howe, the anthropologist, he had argued for quite some time before that the Homo sapiens were so different to the other things, the other, the other thousand so on, that we probably had a different origin and a single origin somewhere.

4:14But when he was proposing that, even in the 60s and 70s, he couldn't say where that place was. And it turned out later, of course, that it was Africa. And when talking about a recent African origin, what time period should we be thinking of? Roughly. Yes, well, the main exit that leads to the diversity of people today outside of Africa happened genetic assessment, around 60,000 years ago. So Homo sapiens, having evolved for a long time in Africa, a small group got out of Africa and then founded the populations of the rest of the world. So that's the kind of recent out of Africa, bit of the story. And we now know that it's more complicated than that, that there were some earlier exits of Homo sapiens out of Africa that didn't end up giving rise to the populations today. And also we know that it wasn't a pure out of Africa. You know, some of us are argued that it's virtually 100% recent African origin.

5:15But now we know that other humans contributed to our ancestry, people like Neanderthals, Denisovans, which come on, hopefully, to talk about. They contributed a bit to our ancestry as well. So now I use the term, which I think was first used by the Spanish papal mostly out of Africa. I think that's the best way of describing it for Homo sapiens origins. And I guess also, is it this was some of that I'm fascinating, the fact that actually our story, our Homo sapiens story, the majority of it is before 60,000 years ago. So there was a lot of archaeology still to be found in Africa itself, do we think, to kind of trace that earlier story of Homo sapiens? That's right. Yes, the main part of the story early, or only certainly an African story. And probably a lot of our behavior originated in Africa as well as an anatomy. And certainly most of our DNA comes from that African ancestral population. One other big question, first of all, we say things like anatomically modern humans and

6:15archaeic humans. What do we mean by that? Yes, those terms, I've used them a lot in the past. I'm not sure they're very good terms, but they're certainly widely used. And so we better sort of go into what they mean for most people. So yes, our own species, Homo sapiens, if we look at people around the world today, we come in many different sizes and shapes and colors, but if we strip away the superficial features of the skin and hair and so on, get down to the bones and the teeth, the things that preserve it fossils, there are certain shared characteristics that we can call anatomically modern human characteristics. And so I've got an example of a replica here, fantastic, of a fossil from Romania that's over 40,000 years old, but here it is with a lower jaw actually from a separate individual. But they show the features of anatomically modern humans. So in the brain case, it's high and rounded, small brow ridge at the front, or maybe no

7:17brow ridge at all, quite a small face tucked under the brain case. It's quite narrow at the base and expanded higher up. So the whole brain shape is different. And when we look at the lower jaw, we can see there's a nice chin on the front. And if we had the whole skeleton, we would see that that too is distinct, that there is a narrow pelvis in Homo sapiens, a narrow shoulder girdle, we're much heavily, much less heavily muscled. So anatomically, we've got more grassarle skeleton, if you like, with slenderer than those earlier species, which mainly seem to be built for strength and power in their skeletons. So those are the shared features that we can look for. There are many more of them. If we take CT scans, even inside the ear bones, we can see that the ear bones of Homo sapiens are distinct from those of Neanderthals. So even these tiny little bones that we can't even physically get to except with CT scans, they're even distinct in Homo sapiens, then from people like the Neanderthals.

8:20So that's the anatomically modern. And our cake is used as the flip side of that. So the things that don't show those features are called archaic humans. And that would cover the Neanderthals and Homo hydropagensis and Homo anticesa, Homo erectus. They're all called archaic humans. I don't think it's a good term because of course it's a big lumping term covering a huge amount of diversity. And actually the Neanderthals are not, in some ways, they're not really archaic, they're very evolved as we are. So if we look at Neanderthal evolution, we can see that they've all bigger brains as we did, their teeth got smaller as ours did. So they underwent changes too. And they're actually derived in their own direction. And as we are derived in our direction. So I prefer to talk about Neanderthals and derived Homo sapiens. Interesting. But the terms archaic humans and Schombri modern are still around. And yes, as a shorthand, I talk about modern humans, by which I mean things that in the

9:22skeleton show these sorts of features. Because I've either tried to derive to humans and basal humans as well. Yes. And so in terms of archaic, I've tended to try and use the term basal. So these are things which are, you know, if you like, if we had an evolutionary tree, they'd be closer to the base of that evolutionary tree. They show, they show more primitive features. So we've got an example here of a skull from Jebl-Ihudya Morokka, a genoreprica. But this one is about 300,000 years old. And I call it a basal Homo sapiens. So it doesn't show all the features of antornomal humans. It shows some of them. So for example, here the brain case is still quite long and low. And there's still a strong garage. But the face, and if we had the teeth and the lower jaw, you can see there there are some Homo sapiens features. But they're not fully developed. So this for me would be a basal Homo sapiens. And this is the key point is a human skull from, and we'll explore Jebl-Ihudya a bit more in time. A Homo sapiens skull from 300,000 years ago, can look very different.

10:25One for 100,000 years ago. And the same in the antitools, early in the antitool, compared with latent cells. That's right. Yes, if we had an adequate cofossil here from 400,000 years ago, from Europe, from Spain, that would show what I call a basal Neanderthal. It shows some Neanderthal features, but it lacks some of the features of the late Neanderthals. For example, the brain's smaller, the teeth are a bit larger. And also there's even DNA from the Atopuerca fossils at 400,000 showing that they are early members of the Neanderthal line. Sadly for Jebl-Ihud, we don't have DNA. DNA, of course, in an African environment doesn't survive so well. So whereas we've got quite good early Neanderthal DNA, we don't have really any DNA of early Homo sapiens and Africa, unfortunately. And all this evidence that is coming to light now, I'm guessing the more, I mean, the previous of you, the theory that we descended from Neanderthals or Neanderthals came before

11:26Homo sapiens, that's now being very much pushed aside. Yes. So the idea that we evolved directly from Neanderthals, that was something I was testing in my PhD back in 1974. I finished it in 1974. And one of the views I was testing was this view, which was a very common view then, maybe the dominant view, was that yes, we evolved directly from the Neanderthals and people like them around the world. And so if we had a complete fossil record in Africa, in Europe, we would see Neanderthals gradually changing into Europeans of today. So the Brow ridges will get smaller, the teeth will get smaller, the skeleton will get more likely built. They gradually develop a chin on the lower jaw. So we'd have this sequence from Neanderthal to Homo sapiens. I was testing that in my PhD and I could see no evidence for it. The Neanderthals seem to be going in their only evolutionary direction as we were. So in that PhD, I could conclude that we didn't evolve from European Neanderthals, but at that stage I couldn't say where we did evolve from that came later.

12:28That came later and that's where we get out of Africa and we're going to that now. We will delve into the nerdy details of the particular theories around out of Africa. Can you give us a bit of an overview right now as to what kind of the key developments in this theory, this hypothesis, what these key developments have been over the past few decades? Yeah. So if we go back to the 1980s when the idea has really started to take off of recent African origin, there already were a few fossils from Africa that seem to look quite modern at an early date. So there's one in particular from Homo Kibish in Ethiopia and I worked on that with Michael Day and we did a reconstruction of the skull and it showed for us modern human features. It had a small brown ridge, it was high and rounded, there was a chin on the lower jaw. There was also a skeleton part of a skeleton to go with it.

13:28That also seemed to show recent Homo sapiens features. Now back in the 1980s, it was argued by some people that it was at least 100,000 years old and mytolyne accepted that dating and therefore this was evidence of a Homo sapiens existing at the same time as the Niantos were alive and it was in Africa. So this pointed to an African origin but at that time we didn't have an ancestor for it, we didn't know where that, it was kind of isolated in a sense in Ethiopia. It certainly pointed to a recent African origin but there were people saying well it's wrongly dated or you were over-interpreted in Atomy, there are fossils in China and elsewhere that look like Homo sapiens too and are just as old. So there was just no clear framework to really say that was the story. There was conflicting data and it took a while for more fossils from Africa to emerge, better dating to emerge and for some of those other, what seemed to be anomalies in other

14:29parts of the world got clearer with their dating. So some of those supposed ancient Homo sapiens in China were not actually Homo sapiens fossils or they were wrongly dated and were much more recent. So we got clarification of some of the more confusing bits of the story but it really started to come together, yes at the end of the 1980s with the arrival of the first bits of DNA from recent humans that started to point to it and then as the evidence accumulated in the 1990s at the early 2000s we got this picture building up that we were pretty certainly at least in my view we looked like we were virtually 100% recent African origin. So I was interpreted in the fossil data, the behavioral data, the genetic data as all pointing to a recent African origin with Homo sapiens and one where if there had been any interbreeding with those other forms of humans it was minimal. And I was aware that closely related species can interbreed and I regarded the Neanderthals

15:31as a different species that was a view that kind of I started to pick up on with a few other people in the 1980s that we went back to using the name Homo Neanderthalenses for the Neanderthals which they'd been given way back in 1864. Then for a long time, certainly when I was doing my PhD it was common to call the Neanderthals Homo sapiens they were regarded as a form of Homo sapiens. So I started with a few other people to argue in the 1980s that actually we should go back to having a separate species name for Neanderthals and a separate species name for what became Homo hydrobegences, reviving that name. But I was aware that in modern mammals for example you can get into breeding between closely related species. So for example, chaps and wolves, brown bears and polar bears, a number of species of monkeys in Africa can hybridize even though we regard them as different species. So I thought it could have happened between us and Neanderthals. We could have interbreed but I

16:34thought that it wouldn't have been an ordinary event, it would be a rare event and then it happened 40,000 years ago. We're never going to find evidence of it today. Of course I'm as wrong about that because in 2010 we got the first reconstruction of a good quality Neanderthal genome. That was published in the journal Science and it showed that indeed people outside of Africa have around 2% Neanderthal DNA in their genomes and that's because there was an interbreeding event maybe 50,000 years ago. So Homo sapiens came out of Africa in this exit maybe 60,000 years ago. Soon after that they met some Neanderthals, they did some interbreeding with them and then as they spread around the rest of the world they took that bit of Neanderthal with them. So not only is there around 2% Neanderthal in people in Europe but it's there in China, it's there in Australia, it's there in Native Americans. So everyone outside of Africa has this Neanderthal component. So we have this kind of paradoxical situation that we did not evolve from Neanderthals which is what

17:39I was testing my PhD but they're partly our ancestors because we've gotten Neanderthal DNA. So so it's kind of you know they're they're a distinct lineage evolving for a very long period of time, hundreds of thousands of years but not evolving to such an extent they couldn't still be a bit of interbreeding and not evolving in Africa alongside ourselves until we got so it's also further evidence for the African origin. So it sounds like it's it's this combination of it's it improved dating over time, the discovery of some really remarkable new fossils and of course the introduction of DNA and the building up of this incredible DNA database all of that combined as well explore helps make it you know why an academic circle is especially this recent African origin is super-svasive today. Yes I mean for me it's persuasive of course there are still people who argue that it's still an over-interpretation of the data that actually the picture is much more complicated that we should acknowledge these contributions from populations in the rest of the

18:42world as being more significant. So we have models like the braided stream model which says that the evolution of our species is more like a river which has many different tributaries that separate off but then they come together emerge and this pattern's been going on for the whole of the evolution of homo sapiens probably been going on for one and a half million years and that really there's no point in having these separate species names because there was a bit of interbreeding going on between many of these different branches that we should call everything homo sapiens. So it kind of goes back to that view that was around in the 70s and 80s that actually let's call everything homo sapiens that's essentially genus homo so even to homo erectus back that far to one and a half even close to two million years people argue that we we really shouldn't call that a separate species even that should be called homo sapiens. Now for me you know I come out of a palatological background I'm in a department with people who work on fossil fishes and fossil reptiles and so on and

19:49the methods they use to establish species in the fossil record are similar to the ones I use to establish fossils in the fossil human record and the level of difference between us and the other animals certainly in my view and and the view of many of them is at the level which in any other animal would be called distinct species. So I still regard them as distinct species even though we know there was a bit of interbreeding but you know we you know I'm not sort of wedded absolutely to the idea but it seems to me that if you call all of those things homo sapiens you really lose any meaning to the term because you know how do we describe what is a homo sapiens well is it got a big brain well not really because the erectus ones are very small brain small teeth well not really because the early ones who got big teeth and the nisophans who got big teeth lack of brow ridges well no there's brow ridges in most of them so even to say what is the brain size what is the brain size of homo sapiens well it's everything from down virtually the size of

20:51a gorilla up to the huge size of an antelope so the term homo sapiens become meaningless more philogically I think if you have this very wide definition we're getting deep into those theories already are we Chris and we won't go into the weeds of what is a species today because I know that it was also that's another episode in its own right if you may allow me to ask a superlative question because we have all this different evidence today but have there been any landmark discoveries that we can say is the strongest evidence that we have today for evidence of an African origin for us species well I think it has to be the genetic data as the genetic which is not a single thing of course it's a massive data that keeps building up you know tens and tens of thousands of genomes and all of them show that first of all if we partition variation in homo sapiens today by far the greatest part of it is in Africa and there are deep lineages there and if we look at

21:56the variation of people outside of Africa it's a tiny subset of that whole variation that we find so just the pure fact of this you know huge diversity in Africa and all of the rest of us being a tiny subsample out of that diversity really does point to a reason African origin and that's true for the white chromosome male inherited for the mitochondria female inherited and for the whole genome so overall I think genetic data are the strongest but we now have a number of other fossils not just homo kibish but there's other fossils in Ethiopia such as from Herto we've got evidence from southern Africa from sites like classes Rivermouth so and we've got the stuff as we mentioned from Jebel Irodi Morocco and later Moroccan fossils that all point to the existence of homo sapiens features and a much earlier date in Africa then we find them anywhere else so Chris let's explore some of these these fossil discoveries and let's touch on the one for which you have a

22:57replica and you brought it up just a bit earlier which is Jebel Irodi so can you set the scene of where this is what we should be thinking with Jebel Irodi yeah so yeah this is a replica of of the first fossil that was found so yeah this was found you know before I done my PhD it was called an African Neanderthal when it was discovered around 1960 so it's from a quarry a working quarry in northeast Africa and Morocco and northwest Africa and north of east Africa so there's a quarry there and in that quarry were sort of cave deposits within the quarry and a number of fossils were found there and this is one of the most complete ones that's been found was it an accident of discovery yes they were working that it was an accident of discovery so this was a commercial quarry and these bones were being found we don't know if any were found before that that were lost but there were so Moroccan scientists did conduct some excavations there when bones were showing up

23:57and this turned up and as I say it was regarded by many people as being an African Neanderthal and originally dated at only about 40,000 years old so when I did my PhD I was lucky enough to be able to measure this when it was in Paris before it went back to Morocco and I could see straight away that it wasn't an undertale because by then I'd seen a number of Neanderthal fossils in my trip around Europe in 1971 and the face on its own was unlike any Neanderthal face it was like a a slightly bigger version of our own face so for me this certainly didn't look like anyanderthal but at 40,000 years old you know it was also too primitive to be an ancestor for homo sapiens so at that time it didn't seem to be particularly relevant for our origins it maybe was a relic persisting from an earlier stage over in a remote area peripheral era like Morocco but a team went back to the site in you know from from about 2015 onwards and did new excavations and they

25:01recovered more material more fossils more stone tools more animal bones and they did much improved dating work and that showed that these Jebbolehood fossils and by then there were a number of different skulls and teeth and jaw bones these were actually about 300,000 years old. And the stone tools were very nice examples of early middle stone age tools so at 300,000 years suddenly this was back in the scene as an important fossil because it did show although primitive it did show some sapiens features and so what do you mean by early middle stone age tool? Yes so yes we've got these stages of the stone age which archaeologists have set up and in Africa we've got the early stone age the middle stone age and the later stone age so the middle stone age in Africa is equivalent to also the middle Paleolithic that's another term lower Paleolithic middle Paleolithic upper Paleolithic Paleolithic being old stone age so we've got the

26:02stages of the stone age and in Africa the middle stone age is the stage that's associated with the beginnings of homo sapiens things like Jebbolehood and the equivalent stage in Europe and Asia is associated with the Neanderthals. So yeah sorry about those technical questions but yes the fact that Ihold was associated with middle stone age tools also showed complex behavior these are very nice you may tools so it suggested that you know again this was not a backward population in in a peripheral area of Africa it showed that Morocco was important in the story of our origins and more work is being done there down to the present day I mean all of a sudden you know in recent years you know redating that is now one of if not the oldest evidence of homo sapiens we have from Africa and more to come hopefully yes I mean it's I don't think this can be the oldest evidence of homo sapiens because work I've been doing with Chinese scientists on fossils from China

27:07suggests that the roots of the Chinese population that we know as didisavans also known as homo longi dragon man that lineage seems to go back at least a million years as a separate lineage and if that's correct that also implies that our lineage and the neonatal lineage had split off and that means our lineage and the neonatal lineage must also go back at least a million years to the to a common ancestor so if that's true then it would in fact is actually a relatively young homo sapiens compared with ones that would be at the beginning of that evolution so this is still very controversial the genetic data suggests that we had a common ancestor with neonatiles and dynisavans maybe 700 thousand years ago we would suggest on some of the fossil data could be at least a million so this is ongoing work but it certainly pushes back the ancestry further even on genetic data and that means that jibblyhood is by no means the oldest homo sapiens there must be

28:11some older ones either we've already got them and we can't recognize them or they haven't yet been found well that's the thing that's the exciting thing could there be almost a million years of story still to learn about from Africa in the story absolutely I mean there must be a deep history them for sapiens to be uncovered in Africa and equally exciting really there must be a deep history fitting and a tolls to be recovered outside of Africa probably and a deep history for the dynisavans and the homo longi lineage that's beginning to be uncovered in China you looking for the perfect podcasts to hunker down with during the longer colder darker nights well look no further than the award-winning after dark myths misdeeds and the paranormal with me maddie pelling and me and ni de laini we are historians and love all things gloomy and macabre from tudor executioners an ancient Egyptian death rituals to which trials and folklore

29:16feel transported back in time on after dark out every monday and thursday wherever you get your podcasts and guess what we're also now on youtube after dark a podcast from history hit and then potentially I guess the next question would be more evidence of early adventures out of Africa by early by a rise of use the term any more basal homo sapiens that we know don't know much about as of yet yes that's right so of course the implication will be that is it really only one very late exit form of sapiens or could there be earlier ones and yes we do seem to have evidence of early exits so I was involved in studying a fossil from a cave so I think Greece called apidima cave and a few years back we published evidence that from that site there's the back of a skull

30:22which had been considered to be niandatol but on our analyses it actually looked like the back of a homo sapiens skull and the dating evidence suggests that it's at least 210,000 years old and what's intriguing is that after that fossil is in the site we also have a proper niandatol fossil at the site maybe 30 or 40,000 years younger the niandatol was there and whatever evidence there was of early homo sapiens had disappeared so the niandatol came back and that early homo sapiens population if it was there has disappeared now not everyone accepts that this is an early homo sapiens and we have to be cautious it is only the back of a skull what was the rest of it like but on that evidence it certainly looks like there could have been an early homo sapiens dispersal and that actually ties up with some genetic data because there's quite an intriguing pattern when we look at niandatol and homo sapiens DNA I mentioned that we have a separation time maybe of 700,000 years for us and the niandatols based on the whole genome but when you look at the mitochondrial DNA

31:27of us and niandatols that's in heritithry females when we look at the white chromosomes of us and niandatols in heritithry males they have a younger ancestry a younger common ancestry maybe only half the age of what whole genome would say maybe 350,000 now that's very strange so geneticists have proposed that there must have been an early exit of homo sapiens out of Africa maybe 300 400 thousand years ago there was some interbreeding with the niandatols and yes that put a little bit of homo sapiens DNA into their genome but also it replaced their own mitochondria and white chromosome with a more homo sapiens like from a more basal homo sapiens these will be basal homo sapiens getting out of Africa meeting niandatols still a bit of interbreeding and changing basically they're replacing their mitochondria and white chromosome with a more homo sapiens like pattern which is why they have a younger divergence on mitochondria and white from us than they do on the whole genome so it's a complicated story but

32:33the epidemiphosal might match that by showing us that they were indeed homo sapiens in some like Greece more than 200,000 years ago and there's also evidence of earlier exits which we can pick up in China and even Australia because there are fossils in China that look sapiens like and in Southeast Asia that looks sapiens like that are well over 60,000 years old so I've mentioned you know the geneticist estimate the main exit was 60,000 years onwards that gave rise to populations outside of Africa today but the fact that you've got fossils in China in Sumatra for example in Laos that are probably 70 80,000 years old means they predate that 60,000 exits so there must have been earlier exits and there's controversial evidence from Australia too so a site called Magia Bebe2 in Northern Australia it's got a very deep sequence and you know

33:34beautifully stratified layers and at about 65,000 years ago on the dating from the sand deposits there's a layer that has complex technology a lot of use of pigments and dated at 65,000 again before the 60,000 exits supposedly and we assume that's homo sapiens because of the complexity of the behavior of course some people say we're out of we know we don't have fossils but that would suggest there was even an early sapiens arrival in Australia at least 65,000 years ago so these earlier exits seem to have happened but they didn't take hold in the same way either those populations died out as seems to have happened in Europe after epidema or maybe they were swamped by the main dispersal that came out at 60,000 that ended up being in larger numbers and it's actually overprinted any signal of those earlier populations that were there. A lot of those at these days are still being pushed back as Australia said good example as well of that now we've kind of

34:36explained all of that and looked at some discoveries and not the importance of DNA I hope you don't mind if we now kind of delve into the theories themselves in regards to out of Africa because it's all well and good saying oh they spread out from here and went there and there and there but what we actually mean by that there's a lot of debate and lots of different theories on there. Yes I mean as you know I've already shown my own views of out of Africa have changed really since those very early simple models things are more complicated the evidence of interbreeding makes things more complicated so yes we could say that you've got the strict recent african orange model and that's the model which the mitochondrial DNA seem to suggest that really we can talk about almost a pure out of Africa. So homo sapiens evolved in Africa pretty much entirely came out of Africa and replaced completely all those other populations and that is just the traditional of the plain or

35:37simple recent african orange and that's the model if you like the one extreme version of a recent african origin and I was always I was never really wedded to that idea although the mitochondria suggested it I was always aware that there could have been a bit of interbreeding but again I thought that would be trivial in the big picture so we were effectively a hundred percent recent african origin even though there might have been some interbreeding. Okay then people like Gunter proposed a model called recent african origin and hybridisation so he proposed that from the end of the 70s into the 80s and we worked together on publications and papers with that model as well and so he argued that yes it was mostly a recent african origin but there was interbreeding on a maybe a bigger scale than I was arguing but we could therefore expect to find some fossils that might show evidence of neonatal features but again in the big picture this would

36:39not be very important and I think Gunter's model is probably closest to what we ended up with with the interbreeding evidence its recent african origin and hybridisation and hybridisation because we're talking about interbreeding between you know what I regard as different species so you know there will be these species coming together even though they're evolutionary separate and I mentioned really that this is something that we know happens quite commonly in mammals or birds. Someone estimated that 16% of bird species today have hybridisation with neighbouring species so it's not as though this is a rare event genetic data shows it's actually a very common event and so that seems to have happened in our ancestry then there was a model called the assimilation model and this was proposed by people like Fred Smith and Eric Trinkhouse again in the in the in the late 70s and early 80s and they were proposing that yes there was an african origin for homo sapiens but it was a much more gradual and diffuse process so basically Africa

37:43dominated the picture because of a larger population so african in a sense was pumping out these genes of more derived homo sapiens features and these were then being assimilated in by the populations outside of Africa so in the end of times we're picking up those bits of DNA and becoming more sapiens like and over in the far east populations were picking up those sapiens like genes that were coming out of Africa and were being picked up by populations there so those populations outside of Africa were gradually transformed with this mixing of DNA into homo sapiens so it's a kind of blend of an african origin and regional continuity so you've got kind of both side by side so it means Africa is important but not as important as the recent african origin hybridization model or the real single origin model would propose that's that's that's a third model three and then we've got the classic multi regional model which argues that basically you've

38:46got ancestral populations for homo sapiens all over the place where everywhere that genus homo lived and evolved they evolved towards homo sapiens so the Neanderthals were evolving to homo sapiens in Europe we have populations in China evolving to homo sapiens there populations in Java and in Indonesia are evolving from what we would traditionally call homo erectus into recent populations in Australasia and in Africa of course there's also a transition from early homo populations towards homo sapiens so homo sapiens evolves all over the world where ancient people lived but there's not speciation they're not going their separate ways because gene flow is keeping them together so gene flow acts like a kind of glue holding them together populations in Africa are interbreeding in ones in western Asia who are then interbreeding in populations in Europe and over in the far east and so there's never enough genetic separation for speciation and it's essentially

39:48the evolution of one species homo sapiens over one and a half million years yeah those are the four traditional yes those are the four traditional models and there's also the braided stream model yes I've got this as well so these are newer models that are emerging it's yes it's a newer name I think essentially it's the multi regional model really under another name so for me it's very difficult to separate it from well probably the assimilation model and the and the classic multi regional model braided stream is really like both of those so it's suggesting that you've got continuity over most of the inhabited world it doesn't get into so much to those tricky issues of species but it argues that essentially there is no single place where homo sapiens evolved and what I've said is well if it is a braided stream then it's a braided stream out of Africa so the braided stream the main by far the main flow is coming from Africa and yes there are these subsidiary channels which pick up some DNA from these other populations but Africa is still the

40:52dominant part of the story and lastly the African population structure model yes so I've been involved with people like an Eleanor Sherry in developing that model and she's really developed this into what you can call a pan-African model okay so the idea is that homo sapiens did not evolve in one place so yeah back in the 70s and 80s with phospholacombo kibish we were arguing some of us that east Africa was going to be very important in homo sapiens origins maybe the most important maybe the single center where it happened the birthplace the birthplace of homo sapiens would be in east Africa other people argue that it could be south Africa so there's different ideas about where homo sapiens originated and the problem is that of course these models were built on where you had the best phosphosol evidence which of course may not be where it was all happening and people have compared this with you know the drunk guy who's looking for his car keys and you know it's night time

41:57and he's lost his car keys and he goes and looks under the street light because that's where the light but in fact his car keys are somewhere else in the dark so it could be that that's our situation that of course we look at the areas where there's the best evidence of homo sapiens origins and that could include Morocco now but what Ellie argued and some of the rest of us joined in on that was that actually there were probably a number of parts of Africa that contributed to our origins so homo sapiens early homo sapiens populations were widespread in Africa they were in Morocco certainly they were in Ethiopia they were in central Africa they were down in South Africa and these populations when they were separated by climate change so for example the spread of deserts at times may have pinned them back and separated them and they went their own way in evolution but at other times when climates improved and there was more rainfall these populations spread into newly green areas met each other exchange genes exchange the ideas so we get a much more complex network

43:00a braided stream if you like but just in Africa where homo sapiens is evolving as a composite of these different populations that finally come together maybe a hundred thousand years ago to become the homo sapiens that then spreads across the whole world so the combining of these populations I said that seems to happen very late in the story of homo sapiens then in their development and from what you were saying earlier that's right yes so this is a complex picture that goes on for hundreds of thousands of years and where only get a kind of coalescence to a homo sapiens pattern both in anatomy and behavior that comes together maybe a hundred thousand years ago also and then emerges from Africa and stays behind in Africa as well and there are some even more complex models which are kind of you know they're as an undercurrent that a number of geneticists are saying well even these models are too simple and actually there is evidence that there's a very deep split in the evolution of homo sapiens that might go back one and a half million years in Africa

44:03and this is an astonishing model it argues that there could have been basically there was one ancestral population maybe one and a half million years ago in Africa it then split into two distinct lineages which then evolved alongside each other one of them then gave rise to Neanderthals and Denisovans and later on to the homo sapiens that we find later on in Africa and then going out of Africa but that second lineage is evolving alongside them for a million years and maybe 300,000 years ago it interbreeds with the homo sapiens that are in Africa and then produces the final push to make homo sapiens as we know it today and it's on the clean model and it's on the homo sapiens and that population then disappears conveniently so it's an incredible story but there are several geneticists now arguing for these kinds of complex models so if that's correct it's even difficult to decide where where homo sapiens starts is it one and a half

45:07million years ago is it when you get that into breeding event maybe 300,000 years ago so this these are newly emerging models and it's going to take a while for them to be integrated and also for the fossil evidence to be put together with them but you know if they're correct then it might bring something like an old friend homo hydrub against his back into the picture so I mean first of all Chris before going to that it sounds as if then like that theory then us today was it not based or what's the word derived or anatomically modern homo sapiens we're you know from that converging we're almost like a blend of different basal homo sapiens groups coming together which I'm getting my head around now yeah I mean we're all having to get a head around it and of course these are models they're they're based some of them on modern genetic data purely some of them doing corporate ancient DNA but they're revolutionary models of course in the depth that they argue for our origins and something like homo hydrub against his so this is a replica of the skull from

46:12cab wave broken hill in zambia it's under ok and we can now date it at about 300 thousand years old and it's you know certainly a non anatomically modern human we've got a massive brow ridge a long low skull angle angled at the back rather a lot homo erectus quite a large brain though that's a modern size brain in there but a big face so this is part of what I've called homo hydrub against his is a species that was widespread it was in Europe it was in Africa probably in almost certainly in Asia as well and I used to argue that it was probably the common ancestor for us and the antitals at that time many people dated this guy at 500 thousand years and that seemed a reasonable date from which we could go to homo sapiens and the antitals from something like this that's what I used to think but of course as we found other fossils as we got younger dating for this fossil at 300 thousand and that means it's about the same age as jibblyhood and it's much less sapiens

47:14like than jibblyhood so I then said well actually I got that wrong the highly began species not our common ancestor it's a side branch that died out but these basal deep split models that I'm talking about from the genetic data they argue that they could have been a lineage along side homo sapiens in Africa for maybe a million years that then interbreb with homo sapiens about 300 thousand years ago and then disappeared well harder against this might come into the picture back into the picture as being that other lineage that coexisted with the evolving sapiens lineage in which case even this could be part of our ancestry too I was about to ask could this actually be a basal homo sapiens well it doesn't too far I mean it doesn't look like homo sapiens so I would have trouble calling it a homo sapiens for me it's a distinct species but it would suggest that there was an interbreeding event which put it maybe 20% DNA into the evolving homo sapiens lineage so a much higher level than has been talked about for the Neanderthals and Denisovans

48:15so it would be a significant part of our ancestry but again in my view we wouldn't have evolved from hiding against this but it would be part of our ancestry an important part of our ancestry if those models are correct but I stress that they're newly emerging models and we're all looking at how they can work and that they're any better testing of course. Are you looking for the perfect podcast to hunker down with during the longer, colder, darker nights? Well look no further than the award-winning After Dark myths misdeeds and the paranormal with me Maddie Pelling and me and Anita Lamy we are historians and love all things gloomy and macabre from Tudor executioners an ancient Egyptian death rituals to which trials and folklore feel transported back in time on After Dark out every Monday and Thursday wherever you get your podcast and guess what we're also now on YouTube After Dark a podcast from History Hit

49:34Chris, try to get you on every couple of years because it always seems that more complex things are coming out and more complex models it's yeah I mean of course it's an exciting time with all these different ideas coming through but it's very difficult to give an overview a simple overview certainly that the experts are confused now as much as everyone else is. Well I know what's the fact that like I was getting my head around it first of all that they're not being this idea of one birthplace but then the same time is saying that there are several different birthplaces of Homo sapiens also a bit misleading at the same time. Yes I mean Africa is still the dominant place in our in our story but of course which parts of Africa I mean if if this story is correct of these two deep separate separate lineages for a million years we were asked how could these lineages remain separate for a million years in somewhere like Africa what was keeping them apart did they live in completely different areas or were they in some way different behavior that they didn't actually interbreed much until this last interbreeding

50:40phaser around 300,000. We've covered a lot about the Homo sapiens too and how complicated it is now for before the main exodus migration out of Africa itself but if we focus on that 60,000 years ago how easy would it have been for Homo sapiens to leave Africa? Yeah I mean that's a good question because we we don't know the precise date of exit we think it was a small group of people or maybe a successive small groups of people but close in time and we don't know what the climatic conditions were at that time because we don't have it precisely dated so at times we know that that region north east Africa and the Levant at times it was relatively arid at times it was were watered with with more rainfall so we guess that it was probably a time when the climate improved and that allowed Homo sapiens to move into the region and because they would have been following their food so if there was an expansion of grasslands and even sort of woodlands and

51:47an expansion of the animals that are feeding on that new you know expansion then the humans are going to follow because that's where their food is so it may be that these people were just following their food incoming out of Africa and you know of course for them well Africa you know they didn't know they were leaving Africa they were going into a new area and that then was the beginning of that out of Africa expansion there are some people who think that it might have been more a forced exit that perhaps there was a deterioration of climate in northeast Africa and these populations were pushed out and that would explain the larger numbers in trying to find a new area so yes so we're not sure if it was push or pull were they pushed out into western Asia or were they pulled out into western Asia by improved conditions and in regards to the routes that they would have taken back then should we just be thinking of Arabia and the Levant you know Syria Palestine as well today that area or could they potentially those in Morocco at the streets of

52:50Gibraltar have made that short crossing to southern Spain well Gibraltar and southern Spain today as well yeah so in terms of the western route via you know the streets of Gibraltar some people do believe that there were crossings early crossing so there are stone tools on an island off the coast of Morocco that look near the toll like but of course we don't have the faucet to show any other tells were there so most of the evidence and this includes evidence of the of the large mammals as well suggest that there were not any early crossings across there of populations in either direction from North Africa to Europe or Europe to North Africa and that those crossings came much later you know the waters there are actually quite dangerous you've got very strong currents through there and so and of course even if a small population got across you know it may not have survived so the majority opinion is that we didn't have early crossings on the western side and that yes it's over in North East Africa some people think that there could have been crossings

53:56at the southern end of the Red Sea where it's very narrow and it would have been a crossing direct into Arabia and more verdant yes and Arabia at times has been much greener so perhaps there were crossings down there but again majority opinion is that it would have been further north through the Sinai and into you know the main parts of western Asia okay well let's go to China and let's go peaking man which is I guess this is we can we can use this skull a little bit for yes how does peaking man and explain what peaking man is as well if you don't mind of course skull in front of me yes how this story potentially fits into the kind of the recent African origin or people used to think it did yeah so this is an example of course of homo erectus one of the classic homo erectus populations from China so these finds began to be made at Djigodian near Beijing in the late 1920s and in the 1930s there were controlled excavations there that recovered a

54:59wonderful suite of fossils that were similar to the ones known from Java and what we now call homo erectus so these populations were in the Beijing area about 500,000 years ago and for people who believed in regional continuity the multi-regional model these were going to be the ancestors of modern East Asian populations for example the modern Chinese and people argue that you can see features in these fossils that come through to modern populations in East Asia today for example having a particular shape of the insides of teeth a relative lack of wisdom teeth or molars these were features that were thought to be there in peaking man as these fossils became known and that can be found in modern Chinese populations at a higher frequency so that was the continuity idea of course the recent african origin would suggest that there is no continuity with erectus there is continuity with Denisovans who are a lineage that we think evolved alongside erectus

56:04so in China we had the continuation of homo erectus down to maybe three or four hundred thousand years ago so therefore over a million years but also alongside them we've got the evolution of homo longi dragon man and we've got this replica over there green color reprigurus is the halving cranium which we think is so it's the type specimen of homo longi dragon man but also pretty certainly a Denisovan so that lineage was in China as well evolving and the erectus lineage died out the Denisovans continued for much longer into bread with homo sapiens and then they died out too so it's this idea that once thought that this meant that kind of contrasted with the recent african origin theory but more recently with the discovery of the Denisovans and so on actually this has been largely debunked now do we think well there are some people in China who are still wedded to the idea that out of the human fossils are important in the ancestry of modern Chinese people

57:09so you know there are some political factors in there as well which are influencing those views and of course it's possible there was a little bit of DNA even because there is evidence that there was archaic integration from a very early population into the Denisovans so possibly erectus well in fact almost certainly there's evidence that erectus into bread with Denisovans and then Denisovans into bread with homo sapiens so there could be some transmission via the Denisovans of erectus DNA into homo sapiens today in the far east so they could even be a little bit fair enough never say never recent Asian origin reason after it's so interesting I guess yes but it's going to be a very small amount of DNA but it could be there at a very small level and Chris like what do you think is the best one sentence answer to homo sapiens origins today I would say that we aren't mostly out of Africa mostly out of Africa that summarizes it for me

58:11I think that's quite nice isn't it as well you brilliantly detailed all those that they're complicated how is getting more and more complicated they're thinking about our story before we leave Africa multiple birthplaces converging of populations to form anatomically modern homo sapiens and you discover it's coming out it seems like there's still so much we don't know and why it's still so exciting but bound to get even more complicated in the years ahead absolutely I mean just think how since I didn't quite PhD just how much has happened it's incredible how much our knowledge is growing and yes in some ways it gets more complicated and otherwise it gets simpler because along the way we can dispense with the incorrect ideas you know as we have new dating we can dispense with the confusion that was created by bad dating where we get fossils that have been wrongly interpreted we can get rid of that confusion so yes in some ways it's a more complicated story I would say it's a richer story it's a more honest story of our origins and I

59:12think what it shows us is that actually homo sapiens origins in my view is not something special if we had this degree of information about the evolution of let's say lions or pandas or crannas they would be similarly rich if we ever have the evidence of guerrilla and chimpanzee evolution which we mostly lack they would have their own rich stories to tell as well so I think this is showing us the way forward that you know when you get more data yes it's a complex story it's a richer story and it isn't just our story all of these other species had their own wonderful origin stories to tell and we shouldn't forget them and of course that's true for any hand it tells for the Denisovans for Hyde of Beganises all of them have their own rich evolution or history that we're only beginning to tell Chris you are one of if not the leading expert on human evolution and early homo sapiens and the developing story in the Anstals we'll have to get you back on as well in the future it just goes me to say thank you so much for taking the time to

1:00:14come back on the show it's been a pleasure again thanks so much for joining us on the ancients today i hope you enjoyed the episode and if you are loving the ancients then why not become a history hit subscriber as a subscriber you will have access to hundreds of hours of original documentaries within you release every week plus early access and add free podcasts you can sign up at historyhit.com slash subscribe see you in the next episode