Human Origins: Did We Begin in Africa?

The Ancients

This episode of The Ancients explores the evolving story of human origins, challenging the traditional 'Out of Africa' narrative with new evidence from

Key takeaways

• The 'Out of Africa' theory has evolved from a simple model to a more nuanced understanding involving multiple migrations out of Africa, not just the well-known 60,000-year-old event.
• Ancient DNA evidence, including mitochondrial Eve and contributions from Neanderthals and Denisovans, shows that modern humans have genetic input from other hominin species.

Main topics

• Human evolution and the Out of Africa theory
• Ancient DNA and genetic contributions from Neanderthals and Denisovans

Notable quotes

"We are mostly out of Africa." – Prof. Chris Stringer on summarizing Homo sapiens origins.

Conclusion

Human origins are far more complex and interconnected than previously thought. While Africa remains the cradle of our species, modern

Transcript preview

Speaker 3 (0:00) Ever wondered why the Romans were defeated in the Teutoburg 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 Speaker 2 (0:27) .com slash subscribe. Speaker 3 (0:31) 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 African 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. Speaker 3 (1:45) 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. Yeah. 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. Speaker 1 (2:03) Yes, Speaker 3 (2:03) it Speaker 1 (2:03) still is the main place. But obviously, the more we learn about some of these other places, particularly places like China, we realise that they're an important part of the story too. Speaker 3 (2:13) And I guess, as we'll delve into, there's going to be quite a sciencey chat and how the out-of-Africa theory, it has developed a lot over the decades, hasn't it? Speaker 1 (2:23) 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 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 Speaker 3 (2:44) so for how long then has this idea, this proposal that, you know, Homo sapiens originated from Africa, how long has that been around? Speaker 1 (2:54) Well, I and a few others started to tentatively propose it in the early 1980s. 1980s, okay. 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. And 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-day 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. Speaker 3 (3:49) I just wanted to ask that because I was wondering if anyone had potentially put forward that theory before the 1970s and the 1980s, but it does sound like that was actually where Speaker 1 (3:57) it really came Speaker 3 (3:57) from. Speaker 1 (3:57) Yeah, that was the beginning. I mean, people like Bill Howes, the anthropologist, he had argued for quite some time before that that Homo sapiens was so different to the other things, the Neanderthals and so on, that we probably had a different origin and a single origin somewhere. But 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 Speaker 3 (4:22) was Africa. And when talking about a recent African origin, what time period should we be thinking of, roughly? Speaker 1 (4:29) Yes, well, the main exit that leads to the diversity of people today outside of Africa happened, geneticists estimate, 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 argue that it's virtually 100 % recent African origin. But now we know that other humans contributed to our ancestry. People like Neanderthals, Denisovans, which we'll 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 Svante Paabel, mostly out of Africa. I think that's the best way of describing it for Homo sapiens origins. Speaker 3 (5:36) And I guess also, this is also something I find fascinating, the fact that actually our story, our Homo sapiens story, The majority of it is before 60,000 years ago. So there is a lot of archaeology still to be found in Africa itself, do we think, to kind of trace that earlier Speaker 1 (5:52) story of Homo sapiens? That's right. Yes, the main part of the story earlier on is certainly an African story. And probably a lot of our behavior originated in Africa as well as our anatomy. And certainly most of our DNA comes from that African ancestral population. One other big question, first of all. Speaker 3 (6:12) We say things like anatomically modern humans and archaic humans. What do we mean by that? Speaker 1 (6:18) 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. Yeah, we come in many different sizes and shapes and colours, 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 in 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 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 brow 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 less heavily muscled. So anatomically, we've got more gracile skeleton, if you like. We're 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, and 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 than from people like the Neanderthals. So that's the anatomically modern. Speaker 1 (8:23) Archaic 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 heidelbergensis and Homo mantisessa, 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 evolved 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, as we are derived in our direction. So I prefer to talk about derived Neanderthals and derived Homo sapiens. Speaker 3 (9:11) Interesting. Speaker 1 (9:12) The terms archaic and anthropomodern are still around. And yes, as a shorthand, I talk about modern humans, by which I mean things that in the skeleton show these sorts of features. Yes, because I Speaker 3 (9:25) have other terms here like derived humans and basal humans as well. Speaker 1 (9:28) 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 more primitive features. So we've got an example here of a skull from Jebel Ehud in Morocco. Yes. Again, a replica. But this one is about 300,000 years old. Speaker 1 (9:54) I call it a basal homo sapiens. So it doesn't show all the features of anatomically modern 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 brow ridge. But the face, and if we have 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 Speaker 3 (10:16) is the key point, isn't it? A human skull from, and we'll explore Jebel Iyikud a bit more in time. A Homo sapiens skull from 300,000 years ago can look very different to one from 100,000 years ago, and the same with Neanderthals, early Neanderthals compared with late and so on. That's Speaker 1 (10:30) right, yes. If we had an Atapuerca fossil 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 Atapuerca fossils at 400,000 showing that they are early members of the Neanderthal line. Sadly for Jebel Iqhud, 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 in Africa, unfortunately. Speaker 3 (11:12) And all this evidence that is coming to light now, I'm guessing the... More, I mean, the previous view, the theory that we descended from Neanderthals or Neanderthals came before Homo sapiens, that's now been very much pushed aside. Speaker 1 (11:29) Yeah, so the idea that we evolved directly from Neanderthals, that was something I was testing in my PhD back in 19, 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 Europe, we would see Neanderthals gradually changing into Europeans of today. So the brow ridges would get smaller, the teeth would get smaller, the skeleton would get more lightly built. they'd 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 seemed to be going in their own 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. That came later and that's where we Speaker 3 (12:29) get out of Africa and we're getting to that now. We will delve into the nerdy details of the particular theories out of Africa. But 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? Speaker 1 (12:52) Yeah, so if we go back to the 1980s, when the ideas really started to take off of recent African origin, There already were a few fossils from Africa that seemed to look quite modern at an early date. So there's one in particular from Omo 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 brow 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. That 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 Myta and I accepted that dating. And therefore, this was evidence of a Homo sapiens existing, you know, at the same time as the Neanderthals 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're over-interpreting the anatomy. 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 parts 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