Origins of Homo Sapiens

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Homo sapiens.

Modern humans.

Us.

Today, we are the only species of human left alive on the planet.

But that wasn't always the case.

When Homo sapiens emerged, they were one of several different species that walked this Earth, and there was no guarantee that Homo sapiens would rise to dominate.

And yet, they did.

So what do we know about the emergence of modern humans?

How far back can we go?

And why do all prehistoric roads lead back to Africa?

We're covering all of that and more in today's episode.

This is the story of the origins of Homo sapiens, originally recorded in the spring of 2022 with with our guest, one of the leading experts on human evolution, Dr.

Chris Stringer.

Chris, on the ancients, on history hit, we've covered some huge topics in the past, but there aren't many topics that get bigger than this one, is it?

The origins of modern humans, the origins of our species.

That's right, yes, it is a big topic and it's one where we've had so many discoveries in the last few years.

Well, you've got a few of these replicas out for us today, which we will no doubt talk about in due course.

We are at the Natural History Museum today.

And Chris, I mean first of all, the past era for research into looking at early humans and early modern humans, early hominins more generally, it's been a really exciting era for discoveries, hasn't it?

Yes, it has.

So we've had obviously wonderful new discoveries of actual fossils.

We've had better dating of some of the fossils that already existed.

And of course, really excitingly, at least for the later part of the record, we've got DNA added to the story for people like the Neanderthals and these people we discovered from DNA data the Denisovans living over in East Asia.

Well you mentioned Neanderthals you mentioned Denisovans we will definitely talk about those but I mean first of all regarding fossils and looking at fossils what qualities what features of a fossil are you looking at when you're trying to decide whether this fossil of an early homonym is an early modern human?

Well yes, so if we haven't got the DNA we're left with what will fossilise and that's obviously the bones and the teeth.

So I've got here a replica of a modern human, recent human skull

and you can see some of the features that typify our species and things we can look for in the fossil record.

So we've got a high and rounded brain case and it's expanded up here at the back.

We've got a small or non-existent browriage.

We've got a small face that's tucked under the brain case.

relatively small teeth.

If we had the lower jaw, there'd be a nice chin on it and here's an example of that on another fossil.

We've got relatively large mastoid processes, even down to our earbones.

So we know from CT data we can look at the inner earbones of fossils and we can see that even down at that level we're distinct from people like the Neanderthals.

And in the skeleton, if we have the skeleton of this individual, our skeleton is lightly built.

So we're not highly muscled compared with some of these earlier humans.

We've got a relatively narrow rib cage.

We've got a relatively narrow pelvis.

Our joint surfaces are smaller.

So even in the skeleton, we've got a whole suite of differences and these are are the things that we look for in fossils to mark the evolution of Homo sapiens.

And the evolution of Homo sapiens, but of course Homo sapiens are just one of the Homo species, isn't it?

So if we delve into the background now in regards to the origins of modern humans, because what do we know going really far back about the earliest hominins that we know of?

Well yeah, so geneticists estimate that we had a common ancestor with our closest living relatives, the chimpanzees, maybe seven billion years ago.

And for the first five million years of that period or so, human evolution took place only in Africa as far as we know.

And then in the last two million years, early humans started to spread from Africa to places like Asia and Europe.

So we start to see fossils in those areas and of course evolution is still going on within Africa and we start to see a diversification.

So for the earliest stages of human evolution we've got fossils in Africa that are close to 7 million years old and some people think that these are actually on the human line other people are not so sure because because of course when you go back to that common ancestor with chimpanzees, it's not going to look very much like us because we've had seven million years of evolution and it probably won't look much like a chimpanzee either because the chimpanzees have had seven million years of evolution from that common ancestor.

I mean does it seem important to stress therefore that by the time we get to the origins of Homo sapiens, the emergence of modern humans, does there seem to be this rich diversity of different Homo species present in the world at that time?

That's right, yes.

So what we see now from the fossil evidence is a great diversity.

At every level where we've got good evidence, we see there are a number of species coexisting.

It's as though nature's experimenting in how to be human with all these different lineages.

And so even 70,000 years ago, which is like yesterday geologically speaking, there were at least five kinds of humans around on the earth.

So we were evolving in Africa and starting to emerge from there.

The Neanderthals, we've got an example of a replica Neanderthal here, they were evolving in Europe and Asia.

Over in East Asia, we had these Dinisovans, who we know about mostly from their DNA.

And we also had on the islands of Southeast Asia two strange dwarf species, one of them nicknamed the hobbit, Homophloresiensis, and one in the Philippines that we've only learnt about in the last few years called Homo luzinensis.

So that's at least five kinds of humans.

70,000 years ago, now there's only one.

So all those other forms disappeared.

As we go back in time, there's even more things like Homo harderbagensis and homo naledi and so on.

So it's a much more complicated story than we used to think.

Well Chris, and there we go, there's the story of the prehistoric Bilbo Baggins, isn't it?

At the same time.

That's right.

Yeah, we can cover that.

All right.

Well, let's delve into the big, big questions surrounding the origins of Homo sapiens now.

When and where do we think Homo sapiens originated from?

Well, the geneticists estimate we had a common ancestor with the Neanderthals and the Denisovans maybe 600,000 years ago.

And I don't think we know what that common ancestor looked like.

I used to think it was this species Homo hydrobergensis sometimes also called Homo rhodisiensis.

So this is a replica of a fossil that was found in what's now Zambia and it was found in 1921.

It was the first important ancient human fossil ever found in Africa.

Just to describe that skull which you're holding now Chris, I mean looking at it at first glance as a Joe Brogs it doesn't look that dissimilar from the skull of a modern human.

I mean his eyes look bigger as well but what are other key features of of his eyes?

Yeah, so we can put them side by side, and you can see there that, you know, the brain case is much longer and lower.

The forehead's much flatter.

You've got this, as you say, great big brow ridge over the eyes.

The face is bigger and it's pulled forwards more.

The teeth are larger.

When we look at the back of it, it's got this strong ridge of bone across here, an occipital torus and strongly angled, so that's a distinction.

And when we've got the skeletons of these early humans, we see that they're very strongly built, very robust compared with our skeletons.

So different from us, I would certainly say a different species.

Sometimes called Homohyderbergensis after a jawbone that was found in Germany in 1907.

Other times, I think I'm switching over to using the name given to this fossil in 1921, which is Homo rhodesiensis, because that was the name given to what's now Zambia, was then northern Rhodesia.

So Homo rhodesiensis.

So this, I used to think, was a common ancestor of us and Neanderthals.

Now I think it's not because it's got some derived features that take it away from what we think the common ancestor was like, especially in the face.

And also we've directly dated this fossil and it's only about 300,000 years old.

So it's too young to be the common ancestor of us and Neanderthals.

And there are other fossils which certainly are closer to that position.

There's a species we know from Spain called Homo antisesaur, pioneer man.

Now that material is 850,000 years old.

It may be be too old to be the common ancestor, but in the face it actually looks closer to what we would predict the common ancestor of us and the Neanderthals look like.

Even though, as you say, we don't think Homo heiderbergensis, I apologise if I butcher the name of that homo species now, might not be their common ancestor.

Is the theory that Homo sapiens emerged from Africa, the out-of-Africa theory, is still dominant?

Yes, so if we go back to that common ancestor, maybe 600,000 years ago, I would say we're not even sure where it lived.

So that common ancestor may have lived in Africa, may have lived in Europe even,

maybe lived in Western Asia.

And then from there, these different groups diversified and evolved.

But after that time, yes, the evolution of homo sapiens takes place in Africa, only in Africa as far as we know, until we get to the last couple of hundred thousand years, we start to see sporadic signs of homo sapiens emerging from Africa, but not surviving, not established long term.

And then there's a major dispersal about 60,000 years ago.

And that is the dispersal that really makes its mark and gives rise to humans today outside of Africa.

So that 60,000-year event is the really important one in terms of modern human diversity outside of Africa.

And humans, of course, stayed behind in Africa.

So the out-of-Africa theory is, you know, I prefer to call it the recent African origin model.

I think that is still the dominant one.

But whereas 20 years ago, I would have said, yeah, we're recent African origin, pretty well 100%

now I would say we're mostly out of Africa because we do know even that story has got a bit more complicated and why I don't use out of Africa as the sort of short term for it is because actually there were other out of Africas so this species Homo erectus most people think that that evolved in Africa more than two million years ago and it came out of Africa around two million years ago.

So that's a very early out of Africa event and there could have been more since then.

There were probably some back to Africa events that we have a very poor picture of and so there were actually a number of outer Africa events.

The most recent one, the 60,000 year one is the one that is the most important in terms of our story and so recent African origin I prefer to use that term for this model of an African origin for our species.

We definitely can.

It's amazing that there were these multiple people going out of Africa in prehistory, in the distant, distant past.

I mean Chris, I'd love to focus in on a few examples of the earliest modern humans we know of from Africa now.

And it seems one of these places in Africa where there seems to be been a lot of discoveries in recent history is in the northeast, is in the area around Ethiopia.

Now what examples do we have from this part of Africa?

Yes, important discoveries there of course at various stages of human evolution but for the Homo sapien story, yes, some fossils were found in the late 1960s from Omo Kibish in southern Ethiopia, close to the border with Kenya.

And one of them, Omo 1, is a partial skeleton with a reasonably complete cranium and jaw.

And for me, that is probably the oldest fossil that has the features that I talked about for Homo sapiens.

So it has a high and rounded brain case, relatively small brow ridge, a chin on the lower jaw.

Pelvis that we've got suggests it's got a narrow pelvis.

Now that fossil has recently been dated to over 230,000 years old.

So that is the oldest fossil that I would call a derived Homo sapiens, a fossil that shows the features of Homo sapiens today.

When we go back further on the Homo sapiens line, we find fossils that have some Homo sapiens features, but not the whole complex that we find today.

And one of those is also from Omo Kibbish.

There's a fossil called Omokibish II found a few kilometers away from the site of Omo Kibish I.

thought to be around the same age, but it's quite different.

I don't have a replica to show you, but in some ways it has Homo sapiens features, like a small brow ridge, but the back of the skull looks more like a hydrobegensis, so more much more primitive.

So Omo II I would call a basal homo sapiens, one that's closer to our common ancestor with the Neanderthals and Denisovans.

So there's diversity in Africa and as we go back there's a site in Morocco called Jebel Ihud

which is a cave site and Finds were made back in the 1960s, but recent work there has found more fossil material and dated it better.

And that material is about 300,000 years old.

So for me, that's a basal homo sapiens, that group of fossils.

And they show some homo sapiens features in the face, for example, in the teeth, but they still have the long, low brain case that we find in these other species.

So, it's a kind of very early Homo sapiens, closer to our common ancestor with the Neanderthals and Denisovans, and therefore less like us because it's further back in time and less derived.

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It's interesting how you got these examples from Eastern Africa.

You mentioned Omno there, and you just mentioned Morocco, so Northwest Africa.

Do we also have examples from South Africa too?

Yeah, so the South Africa story is interesting, and I think we still have a lot to learn about that.

So there is a fossil from a site called Florisbad, thought to be about 260,000 years old, and that looks a little bit like those ones from Jebel Ichud.

So similar in age maybe and similar in morphology, but also down in South Africa, we've learned in the last 10 years that there's a much more primitive species down there around 300,000 years ago called Homo Neledi.

Now the remains of Homo neledi have been found deep in a cave system not far from Johannesburg and this is a much more primitive species.

In some ways it looks much more like fossils that are one or two million years old and yet it's only 300,000 years old.

So the skeletons and there are partial skeletons from there show a creature which was walking upright, well adapted to walking upright with quite dexterous hands apparently but when you look at the shoulders when you look at some aspects of the hands it looks like this creature was probably still climbing around in the trees as well.

So, and it's got a small brain.

It's only got an basically the brain size about the size of a gorilla's brain.

So even though this is only 300,000 years old, it seems to represent a much earlier stage of human evolution that has survived in South Africa until quite recently and must have lived there.

Just as Homo sapiens was evolving in the north of Africa, we had Heidebergensis probably still in Zambia or Odysiensis.

And there's this weird primitive species still around in southern Africa.

So I think there's more to learn about that story down there.

And Chris, it is so interesting and I was literally about to repeat what you say because I've got in my notes places like the Kalahari Basin as well as Border Cave.

These seem like areas where there might be future discoveries made in the years ahead that cast more light, put more light on this area of...

I think so.

I mean the Naledic finds were a complete surprise.

No one predicted there would be something so strange still there 300,000 years ago in a cave that was thought to have been quite well explored.

But just in this deep little side chamber very difficult to get into they found this treasure trove of fossils thousands of fossils of this homo naledae so that's an example of what can still turn up and surprise us and for africa as a whole you know i would estimate we've only got fossil finds from maybe 10 of africa so central and west africa have produced virtually nothing of the early evolution of homo sapiens or homerodisiensis so who knows who was living there 300 000 or 500 000 years ago we know people were there from stone tools but we have no fossils to show what they look like.

So I think even the African story, we're getting good detail in some parts of Africa, but other parts are still a blank sheet and a lot still to learn about that.

So we've covered case examples from the east, from the west and from the south of Africa.

Do you therefore think it's likely that Homo sapiens evolve in one or from one particular place?

or from many different places?

Yeah, that's a difficult one to answer, of course, when, as I say, we've got evidence lacking from much of Africa, but I've certainly moved away from the position of thinking there was one area that was the most important.

I used to think East Africa was the most important because that's where we had fossils like Omo Kibbish.

But now I think, you know, I'm part of a group who have developed an idea of a pan-African origin for homo sapiens, that we didn't just evolve in one place.

Some people have suggested from mitochondrial DNA that we evolved in southern Africa.

Other people point to, you know, the white chromosome DNA suggesting we came from West Africa.

But the reality is that it's a more complex origin.

I think what we call homo sapiens today is a kind of an amalgamation of different lineages in different parts of Africa that at times were evolving separately.

At other times, when the climates allowed it, they spread and they met and mixed and they exchanged genes and ideas.

So we actually get a kind of complex web of interactions in Africa.

Some of these populations become extinct when the climate turns against them.

Others carry on.

And so we finally get a merging of these groups in the last 100,000 years to become homo sapiens as we know it today.

Well then let's you mentioned their DNA because I'd like to therefore talk a bit more about the science behind what you and your colleagues have been doing over the past few decades around this topic, the origins of modern humans.

And particularly this key paper from the late 20th century that seems to be really important,

the mitochondrial eve.

Now I hope I've said that right because Chris, what is this?

Why is it so significant?

Yeah, so I think it was significant as representing a kind of turning point in the story about a recent African origin.

So I and a few of us were developing the idea from the fossil record that we had an African origin maybe in the last 100,000 years, I would have said then.

But there was probably a dominant view that Homo sapiens had evolved all over the world where ancient humans lived.

This is called the multi-regional model.

So the multi-regional model said that, yes, in Europe there was a line of evolution from the Neanderthals to Homo sapiens.

In Africa, there will will be a line of evolution from hydrobodensis or rhodisiensis to homo sapiens.

In China Homo erectus would have evolved through to homo sapiens.

In Indonesia Homo erectus would have evolved through to recent native Australian populations.

So there was this view of a long-term evolution of homo sapiens covering the best part of two million years.

So this evolution of homo sapiens all over the world but exchanging genes so they didn't speciate into different species.

They remained homo sapiens but they evolved everywhere.

Now that was probably the dominant view in the early 1980s.

But mitochondrial DNA came into the picture.

So a group of scientists based in Berkeley in California studied the mitochondrial DNA of modern humans based on material from modern human females.

So mitochondrial DNA is inherited through mothers to daughters.

So it's a female inherited DNA.

It's only a tiny bit of the genome.

It's actually a separate bit of the genome.

Mitochondria have their own bits of DNA.

And so when you look at mitochondrial DNA in people today, you're tracing back a lineage of females into the past.

So these scientists published a paper in Nature in 1987, arguing that if you took this DNA from around the world, mitochondrial DNA, it coalesced back to a single female individual, a single mother, if you like, for humanity.

She's been nicknamed mitochondria leave.

and she lived on their estimate about 200,000 years ago in Africa.

And so all of the mitochondrial diversity today will trace back to this woman.

So I think it was great in terms of really changing the picture because here was a completely independent line of evidence, nothing to do with fossils that said we had a recent African origin.

So it was very important, it made the headlines all over the world.

But in a sense, it was good and bad because it gave this strong signal of recent African origin.

But of course, mitochondria DNA is only a tiny bit of our whole genome.

And to get the story of Homo sapiens origins, we of course need to look at all the rest of our DNA.

And as we'll see later in this talk, that may give you a more complicated picture and even the picture I've said already about just one area of Africa being important some people have used the mitochondrial DNA data to say yes we can place modern human origins in southern Africa about 200,000 years ago based on mitochondrial DNA and others have argued that that's just one bit of the evidence and when you look at the whole pattern when you look at the fossils the archaeology and the rest of our genome it's much more complicated and southern Africa could be part of our story but it's certainly not the unique place where homo sapiens originated.

Well Chris this is all really great so far and I know we've covered quite a lot of ground already so I hope you don't mind if you give us a quick a summary almost of what we've been talking about you know what we know today in May 2022 what do you think is most likely about the origins of Homo sapiens given all this fossil evidence that we have also this DNA evidence and all the research that's gone into it?

Yeah, so just to do the most simple story is that probably around 600,000 years ago, there was a common ancestor for us and the Neanderthals and Denisovans and we don't know where it lived but it gave rise to these different lineages so in Europe and Asia it became the Neanderthals in Western Europe and in Western Asia it became the Neanderthals over in Eastern Asia it became the Denisovans and in Africa it became Homo sapiens so in Africa we then had the evolution of Homo sapiens probably not just in one area but sort of mixing and matching across Africa and then finally coalescing to what we call Homo sapiens about 100,000 years ago and then about 60,000 years ago a major dispersal from Africa to give rise to the people we find today outside of Africa.

Well let's now focus therefore on this dispersal from out of Africa.

So what do we know about the nature of this dispersal of Homo sapiens out of Africa?

Well yes, so it's known really from a reconstruction of working backwards from the DNA today of people outside of Africa.

It coalesces to around 60,000 years ago.

So it's thought that a small group of Homo sapiens got out of northeast Africa into Western Asia and from there gradually dispersed to where we find homo sapiens today outside of Africa.

And as I say it wasn't the first movement of homo sapiens out of Africa because we've got fossils of homo sapiens for example in Israel that are maybe 120,000 years old at sites like Shkul and Cafsay but in a sense it looks like they didn't go further with their dispersal or if they did it didn't ultimately give rise to the populations we find today.

There's even a fossil from Greece that's over 200,000 years old from a site called Apidima.

Just the back of a skull, but the back of that skull looks very like a homo sapiens, even though it's more than 200,000 years old.

That again looks like a, you could call it a foul dispersal, because there are Neanderthals that come back to the site afterwards.

So there may have been these early attempts at dispersal by homo sapiens, but it's the one at 60,000 that is successful.

But of course, going out of Africa 60,000 years ago was going to take these homo sapiens into the territory of these other humans who were already living outside of Africa, the Neanderthals and the Dinisovans and even these other species that were living down in Southeast Asia.

So that's where we get the possibility of contact between these different forms of humans who've been largely evolving separately for hundreds of thousands of years.

Well let's talk about these interactions with these different types of humans then now and let's focus on the big one then the Neanderthals.

What do we know about Homo sapien interactions with Neanderthals as they spread out of Africa?

Yeah so 20 years ago if you'd have have interviewed me, I'd have said, well, we and the Neanderthals were closely related.

There could have been a bit of interbreeding because, you know, we know that modern mammal species that are closely related can interbreed.

So jackals and wolves, brown bears and polar bears, and many species of baboons in Africa can do a bit of interbreeding.

Now, I knew that was there, but I thought, well, 40,000 years ago, this wouldn't have been normal behavior.

These were small populations.

They probably didn't meet each other very often.

And then we've had 40,000 years since to lose any trace of the interbreeding.

So I thought, yes, it could have happened, but it's trivial in the big picture.

We're never going to find evidence of it today.

But in 2010, work started to appear that showed that clearly modern humans today have Neanderthal DNA in their genomes.

So there was interbreeding, and you and I probably have around 2% Neanderthal DNA in our genomes from this interbreeding that happened.

between about 40 and 60,000 years ago.

And that's true for pretty well everyone living outside of Africa today has around that level of Neanderthal DNA in their genomes.

So it happened.

And the first view was it must have happened when we first came out of Africa in Western Asia.

We now know it was happening in Europe.

It was happening even across Asia.

So there were multiple interbreeding events with the Neanderthals contributing little bits of their DNA eventually to our genomes.

To begin with, it would have been a high level.

So here we've got a replica of a jawbone from Romania that's directly dated to about 40,000 years ago.

Now that's the time when the

were going extinct physically.

Now this jawbone, it's got a nice chin on it, so it looks like a modern human jawbone, but people noted that it had unusual features in the teeth and a little feature here that you often find in Neanderthals.

And what's that here?

What's the Aldoto feature?

It's a little foramen, just a little bridge across the bone here, which you find in about half of the Neanderthal fossils.

That's right to the back of the mouth.

That's right, back of the jaw, inside the jawbone here.

So people were saying, well, it's got some strange features.

Maybe it's got mixed features.

Well, when its genome was analysed, it was found that it had around 9% of Neanderthal DNA.

So that's the highest level known in any Homo sapiens fossil.

And that suggests this individual had a Neanderthal ancestor within the previous four to six generations.

So we're very close to that interbreeding with the Neanderthals in this fossil from Romania.

It's so interesting, you know, how in really recent research this has come to light.

It must be one of the great,

shall we say, discoveries, uncoverings of recent history looking into early humans.

That's right, yeah.

It is a very important discovery, and it shows that we are not purely recent African origin.

We're more than 90% in our genomes recent African origin, but these extra little bits are added on from Neanderthals, from Denisovans.

In Africa, too, there are suggestions that there was some interbreeding, even in Africa, of these other pre-Homo sapiens or alongside Homo sapiens and lineages, even though in Africa we're doing a little bit of interbreeding with Homo sapiens.

So it's it's a more complex story.

We're mostly out of Africa, mostly recent African origin.

And of course people are looking at what that DNA is doing.

So even there's about 2%, as I say, in us, you know, most people outside of Africa today.

And some of that DNA is active.

So it seems to be active in our immune systems, for example.

And that's interesting because, of course, we, having evolved in Africa, coming out of Africa to live in Europe and Asia, we had no natural immunities to the local diseases and pathogens.

The Neanderthals had evolved some of those natural defenses.

So by interbreeding with them, we got a kind of quick fix to our immune system and picked up some of their natural defenses.

And that was good news 40 or 50,000 years ago.

Now it is also linked with some autoimmune diseases.

So this even has medical importance.

So it's kind of swings and roundabouts that this interbreeding can give you benefits in terms of picking up lost diversity.

It has benefits in picking up innovations in other lineages that they've evolved.

You can pick those up as well.

But of course, when your genome integrates these bits of DNA from other lineages, they may or may not fit perfectly and it may be useful, but it also may have some side effects which aren't so good.

So it's a balancing act really.

And we now know that many close-arated mammal species do hybridize and they do this, so this helps to increase the diversity and pick up innovations from other lineages.

But of course, it may also have some less good effects in some individuals.

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So you mentioned Denisovans there.

So what are the Denisovans and how do they relate to our Homo sapiens origin story?

Yes, so of course we didn't know about Denisovans.

You know, if I was talking to you more than 10 years ago in the Altai Mountains, they'd been digging there for more than 50 years and they'd found fragmentary human fossils.

But apart from that the teeth were very large, it was impossible to say what species they were.

And then DNA was recovered from some of these fossils, really high-quality DNA.

And what it showed was you had a different kind of human.

You had a human that was different from Neanderthal genomes and different from Homo sapiens genomes.

And these became known as Denisovans.

So from 2010, we've known about the Denisovans.

They represent a distinct line of evolution over in Eastern Asia.

One that probably branched off the Neanderthal line very early, probably more than 400,000 years ago.

An early branch from the Neanderthal line and a diverse branch too.

So these Denisophans, we know even from Denisova Cave, they were there for at least 150,000 years.

And remarkably, not only were they there, but at times the Neanderthals were there as well.

So we actually have some fragmentary Neanderthal fossils from Denisova Cave and we have their DNA as well.

And incredibly, we even have what seems to be a first generation hybrid between a Neanderthal and a Denisophan.

So there is a bit of fossil of a girl that lived there probably around 100,000 years ago and she had a Neanderthal mother and a Denisovan father.

So quite incredible.

So not only were our ancestors interbreeding with Neanderthals, but the Denisovans were interbreeding with Neanderthals as well.

And even more than that, once we had the Denisovan genome, geneticists started to look at genomes of modern people today and they found chunks of Denisovan-like DNA in people today, particularly over in Southeast Asia and Australasia.

So populations in the Philippines and Australasia, some of them have about 4% of DNA from a Denisovan-like ancestor interbreeding maybe 40 or 50,000 years ago.

That's in addition to having the 2% that they have from Neanderthals from when Homo sapiens first came out of Africa.

So it's really quite an amazing story.

And it looks like Denisovan DNA is around also in mainland Asia.

It's found in Native Americans as well.

So that's been carried across into the Americas.

And it looks like Denisovan DNA has come from separate interbreeding events by separate populations of Denisovans.

So a lot of diversity.

It looks like Denisovans must have been widespread.

They were not only up in Siberia, probably in China, we might get onto that later, but also they must have been down in Southeast Asia.

So when modern humans dispersed through southern Asia and through Southeast Asia, somewhere down there, there was interbreeding with the Denisovan-like population, and then they took it with them when they colonized the Philippines and New Guinea and Australia and so on.

That's insane how DNA is mentioned.

You You can see Neanderthal DNA, you can now see Denisoban DNA.

You mentioned we're going to China now and the Far East because is it a similar story with Homo erectus?

Yes, well Homo erectus of course is a more ancient species.

So erectus was around in Africa around two million years ago and this species ultimately is probably the ancestor of us and the Neanderthals.

You know all of these later humans ultimately derive from erectus or something very like it.

And erectus was a species that was long-lived and it was the first human that we know of that got out of Africa and into Asia certainly, possibly into Europe as well.

It's not certain that erectus was in Europe but there were humans in Europe more than a million years ago and it's not clear what species they were.

But erectus was a long-lived species.

We find its remains in Indonesia, in China.

First remains of erectus were found in Indonesia in the 1890s.

So that species, as far as we know, is the longest-lived human species and until Homo sapiens, the most widespread.

Now, some people, and I'm one of them, really, think that probably when we study these erectus fossils in more detail using the latest techniques, sadly probably not going to include ancient DNA, but there's also a parallel method that looks at fossil proteins called proteomics.

And that method might be applicable to Homo erectus fossils.

So I think erectus probably had great diversity and probably actually when we study it in detail, we'll find that there are more species.

So some people have got the name homoagaster that they use for the earliest erectus fossils that we find in Africa and some people use it also for fossils found in Georgia in the Caucasus.

So these are ones that are over one and a half million years old.

So primitive erectus sometimes given a different name homoagaster.

I don't think that division works very well but I think probably if we look at those earliest African and Georgian erectuses they will eventually turn out to be different from the ones we find in China and Java at a much later date.

And erectus seems to go on a long time in places like Indonesia, probably down to 100,000 years ago, possibly even younger.

So it's even possible that erectus was still surviving there when Homo sapiens moved through the region, but that's not clear.

The youngest erectuses in Java are probably 100,000 years old.

In China, we think erectus may have disappeared about 300,000 years ago.

But again, that's not really clear.

Well, let's talk about one other species before we really start wrapping up.

We've got to talk about the prehistoric Bilbo baggins, of course.

Now, Homoflorenciensis.

I might have once gone that wrong.

Homo floresiensis, what is this species and how can that species potentially relate to our origin story?

Well, I think it's still a very mysterious species.

It's a remarkable find.

So this was published in 2004.

And again, it was a great surprise for pretty well everyone that on the island of Flores, which is beyond where we thought ancient humans ever got because they didn't have boats.

So this is is an island, quite a remote island beyond Bali, sort of heading towards Australia.

So this island, there were claims that humans were there from stone tools, but these were disputed.

Early humans were there.

And then these fossils were found and published in 2004 of what seemed to be a dwarf species of human.

So really a small stature, just over a metre tall.

There's a reasonably preserved skeleton with a cranium, small brained, brain about the size of a chimpanzee, very human teeth, but no sign of a chin, a brow ridge over the eyes, and a skeleton that had a mixture of features that we expect in humans.

So walking upright, but in the feet, in the hands, in details, it seemed much more primitive.

It was really much more like in some ways fossils that are two million years old than ones that are, well we now know, 60,000 years old, some of these fossils.

So as modern humans were coming out of Africa, this strange species was still surviving, probably having evolved there.

on Flores for over a million years because Flores has got stone tools over a million years old and and there are even fragmentary fossils about 700,000 years old which look like the ones that we find later on of Homo fluoresiensis.

So a long deep lineage evolving separately in isolation for a long period of time and then going extinct and you know that's one of the questions of course is why are these other human species going extinct around this time?

But that's so interesting that you actually mentioned there around tools because it might seem obvious to you but to many people, myself included, you might get the mistaken impression that Homo sapiens are the ones with tools and stone tools and the like, but there are many previous, many other types of hominins that were able to use tools long before Homo sapiens.

Yeah, that's right.

Yes, I mean we are a tool using human and tool making human, but this is something that's been around for over two million years.

So we know that something was making stone tools in Africa more than two and a half million years ago, and this is even earlier than some of the earliest homo fossils.

So it's likely that this earlier stage of humans, the Australopithecine, the southern ape phase in Africa, some of those creatures, which in many ways were ape-like in terms of their brain size, they were probably already using and making tools.

Fairly basic, of course, at that stage.

And things like wood, that would have been used, but of course, pretty well all the evidence has disappeared.

So what survives are stone tools, but they're certainly there more than two million years ago in Africa.

We may find them around butchered remains suggesting that these stone tools have been used to butcher animal carcasses, to cut off the meat, break open bones to get the marrow.

So that's something that's there over two million years ago.

And so by the time we get to the Neanderthals and us, we're talking about very sophisticated tool makers and tool users.

So much more complex technology, specialized tools for cutting meat, for cutting wood, for breaking open bones, for processing skins, things like that.

We get quite specialized tools.

Yeah.

Chris, this is all so, so interesting.

I could ask questions for hours about this, literally, but we're going to have to start wrapping up now.

I mean, a last kind of question and statement.

It's absolutely extraordinary for what you've been saying about the progress, the advancements that have been made over the last 30, 40 years, a really exciting era for looking at the origins of Homo sapiens and other homonyms.

But from what you've also been saying, these new discoveries, new DNA research, even to this day, it's really exciting for the future, isn't it?

When we're starting to learn even more, we're going to find even more discoveries shedding new light on this very distant but important part of our past.

Yes, absolutely.

I mean, we've had important discoveries and those are going to continue and as I mentioned there are these empty spaces on the map.

So large parts of Africa with no human fossils for this time period.

The Indian subcontinent with only one significant human fossil from that whole area.

So many parts of the world still yield important evidence, DNA data to come.

I mentioned this method of proteomics where we can look at fossil proteins which have a longer term survival than DNA and that method is going to be increasingly applied to these fossils and that will help us also relate these fossils to each other.

Better dating techniques of course.

So all of this I think we can look forward to a very rich story still to come.

More complexity, but also probably sorting out some of these questions that I've raised that are still doubtful.

So where did homophyzensis evolve from?

We don't know that.

Where was the common ancestor of us and Neanderthals living?

We don't know that now.

We may get discoveries.

I hope we'll get discoveries that will help us home in on those.

And also, what did the Denisovans look like?

We haven't talked much about that.

But the Denisovans, of course, are known from fragmentary fossils.

There is a jawbone from China that's thought to be Denisovan, but somewhere in China, I'm sure there are some much more complete fossils that are Denisovans.

And so that's something that we can look forward to for the future.

Well, China seems to be this key place, doesn't it?

You mentioned just before we started recording Dragon Man, this new discovery, it also seems to have seized the world and its importance.

Yes, yes, it's a fantastic.

It's a beautifully preserved fossil, over 150,000 years old.

And it seems to represent, for me, a distinct species living in China.

I'm calling it Homo daliensis.

And of course, people are saying, well, that's a Denisovan.

For me, that's not yet resolved.

It may well be a Denisovan, but we have to demonstrate that scientifically.

Well, Chris, this has been absolutely awesome.

And it just goes for me to say thank you so much for taking the time to talk to History Hit today.

I've enjoyed it very much.

Thank you.

Well, there you go.

There was Dr.

Chris Stringer talking through the origins of Homo sapiens.

And that was the first ever episode I recorded with him.

We did it in person at the Natural History Museum and ever since then we've recorded quite a few episodes together on The First Britons, Dragon Man and of course most recently our Blockbuster episode on The Last Neander.

So Chris, thank you so much for being such a wonderful expert and it all started our journey on the ancients together back with the episode you've just listened to.

Thank you for listening to it.

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That is enough from me, and I'll see you in the next episode.

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