How did we go from ancient apes to the dominant species on Earth? The story of human evolution is one of survival, adaptation, and extinction - stretching back 7 million years.In this episode of The Ancients, Tristan Hughes is joined by Dr. Henry Gee to unravel the complex origins of humanity. From the first bipedal hominins to the evolutionary leaps that set Homo sapiens apart, together they explore why humans evolved from long-armed tree dwellers to upright walkers and discuss the the advantages that bipedalism gave our ancestors over other species.More from Henry Gee:The Origins of Life on Earth: https://open.spotify.com/episode/3Rb4OcjbmsjIHpFemJ7mmOFeathered Dinosaurs: https://open.spotify.com/episode/05wbG2dMp174D10gP30kIjMore on this topic:Homo Erectus: https://open.spotify.com/episode/3MjgWtiENDpVXc5qv77oTyHuman Evolution: Dragon Man: https://open.spotify.com/episode/128XsUffcThVirTghas7OAPresented by Tristan Hughes. Audio editor is Aidan Lonergan, the producer is Joseph Knight. The senior producer is Anne-Marie Luff.All music courtesy of Epidemic SoundsThe Ancients is a History Hit podcast.Sign up to History Hit for hundreds of hours of original documentaries, with a new release every week and ad-free podcasts. Sign up at https://www.historyhit.com/subscribe. You can take part in our listener survey here: https://insights.historyhit.com/history-hit-podcast-always-on
Chapter 1: What is the story of human evolution?
It's The Ancients on History Hit. I'm Tristan Hughes, your host. Today we're covering the rise of humans. Yep, that's right, human evolution. It's a story that stretches back some 7 million years, one that begins with ancient apes and ends with us, with many different species of early humans emerging and disappearing in between. The story of human evolution is one still shrouded in mystery.
Not only is the fossil record for early humans extremely limited, but so much of it is still debated. Including the all-important question, why did early humans, or hominins, why did they become bipedal? How did they evolve from long-armed tree dwellers to two-legged runners? These radical changes in bodily structure that have occurred over millions of years.
Joining me to talk through this evolution story is a fan favourite of the podcast, Dr Henry G. Henry has been on the podcast before to talk about both the origins of life on Earth and the dinosaurs. Quite a few of you have been clamouring for us to have him back on the show and I'm delighted to announce his return to talk about the fascinating story of the rise of humans.
Henry, welcome back to the podcast. It has been too long. Thank you very much, Tristan. We've done Top 5 Dinosaurs. We've done the wonderful story of the origins of life on Earth. And this feels like another story, the rise of humanity. And Henry, this is a story, I mean, to start with, it takes us back more than 5, 6, 7, 8 million years.
There's a lot of history and ancient history and prehistory to cover here.
Yep, that's right. The human history, well, ancient history, has a very, very long run-up. I mean, recorded history is barely 5,000 years, but this one goes into 98% of human history, which has no written record, and we just pick up from fossils and other scraps of information that we can tell from rock.
And to tell the story of human evolution, as we're going to be covering several million years of history... You mentioned fossils. How rich a record do you have for studying human evolution? Do you have many examples of fossils from millions of years ago surviving?
No, that's the thing about human evolution. The fossils are very uncommon generally, except in certain places. You can count the number of fossils on the fingers of one hand, but the amount of fossils that tell you anything about human origins, you can count on the fingers of one thumb. They are very, very, very tiny, very scarce, mostly teeth like mammals generally.
But the thing is that humans in the very broadest sense, meaning all our ancestry going back to apes, were always very rare in the landscape. I remember going to East Africa to join an expedition looking for fossil humans living 3.3 million years ago.
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Chapter 2: How did bipedality evolve in early humans?
Oh, absolutely, for sure. Not only were there likely to be more, but the thing about fossils is fossils is where you find them. And they tend to be more common in some places than others. So people tend to look in the places where they already know fossils tend to be common. So the caves of South Africa have always had top billing. The Rift Valley of East Africa has been a plentiful source.
And people have been looking in other places and finding new things in Southeast Asia, for example. And there are quite a lot of very mysterious fossils from China. And places like India have hardly been explored because maybe the relevant rocks are not found. West Africa. It looks likely to be a focus of renewed interest. There are all sorts of interesting stone tools.
But one of the problems with West Africa, it is covered in forests, which is very untidy for paleontologists who like to look at deserts where the rocks are more exposed.
So there are all sorts of places that people are beginning to look, and West Africa has some very interesting archaeology, that is their stone tools, going back, and there are beginning to be some surprising results coming out of there.
But the biggest surprises of the past 25 years have been in Southeast Asia, where there are a lot of limestone caves, huge numbers of limestone caves that are barely explored. And there is also... Now we can look at the whole genome, the whole DNA of modern people, but also the whole DNA of some extinct species such as Neanderthals. and another species called the Denisovans.
We know more about these species from their DNA. And also we find some of the DNA is incorporated into the genes of modern people, such as you and me. Neanderthals particularly, I think, looking at me, I probably have more than you do. But there are some species, human species, which are only known... on bits of DNA in the genomes of living people.
It's a bit like identifying Cheshire cats from their smiles. And so there are more. Whether we'll discover more is an open question, but there will be more discoveries. They do tend to happen rather unexpectedly and not very often.
Right, Henry, now let's delve into the story. We are sitting comfortably. When does the human story begin? We go back to apes, I'm presuming.
Yes, 10 million years ago. Cast your mind back, if you will, to the earth 10 million years ago. There were more forests on the earth. And we're talking about what we used to call the old world, Eurasia and Africa. And there were a lot of apes. There were quite a few apes in Europe and in Africa and in Asia.
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Chapter 3: What evidence do we have of early hominins?
And in the tropics, the cooling is manifested as forests dying out to be replaced by a more mixed habitat of what you might call savanna or parkland with grasslands and a few trees here and there. And the number of apes diminished, and monkeys became more prevalent. So there were a few apes hanging on. But after about 10, 9 million years, the fossil record of apes almost disappears completely.
And so until the turn of this century, there was essentially no record of apes or humans or possible human relatives between 10 and 5 million years ago. None. None at all. And then suddenly, just after 2000, an entire skull dropped right into the middle. It was about 7 million years ago. And this came from Chad in Central Africa, which hadn't been very well explored.
And it was an entire skull of a creature called Sahelanthropus chadensis. Sahelanthropus. And it's an unbelievably hard place to work. I mean, it really does look like a blasted desert. And people, I've seen people come, I haven't been there, but I have seen people who've come direct to France, because it was a French and Chad joint expedition.
I've seen people come back to France directly from Chad without washing, and they look yellow, they look completely sandblasted. So, but Salampus chalensis was a whole skull, and also there was a couple of elbow joints and a bit of a leg bone that was described later. And these vines, they haven't been directly dated, but there are lots of other animals found there.
And looking at the complexion of the fauna, you can tell that it's about 7 million years old. But the interesting thing about Sahelanthropus is it looks like an ape. The skull's about the same size as a chimpanzee. But the hole in the base of the skull, where the spinal cord goes in,
is right in the middle at the bottom or almost rather than at the back and that's crucial because a skull that balances on the spinal cord that's on the bottom it comes from an animal that's a biped it walks on two legs if the hole that the spinal cord goes in is at the back of the skull that suggests that the animal is like your sheep or your cat or dog I have a sheep skull here.
Henry is standing up to fetch the sheep skull, which is right above his office setup.
Here is a skull I prepared earlier. This was a sheep skull I found when I was nine. And if you look, that's the hole where the spinal cord would go in. And it's right at the back of the head. It's right at the back. So if you look at the base of the skull, there's the hole. It's called the foramen magnum, which is Latin for big hole. So let's call it a big hole where the spinal cord goes in.
In hominins, that is members of the human family, that hole is moved much further to the center. So the skull would balance on top. And that indicates the one thing that suggests that the owner of the skull was a hominin. And that means a member of the lineage that led to humans as distinct from our closest relatives, chimpanzees. And so Sahelanthropus
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Chapter 4: What role did the genus Australopithecus play in human evolution?
It'd be fascinating to know, hopefully in the future more evidence will emerge, learning a bit about that whole evolutionary step, diversity of early bipedal chimp phase. What could come in the future there?
Well, you know, the thing about paleontology is you must expect the unexpected. So who knows what would come? But I would imagine that when people start looking, if they find deposits of that of a similar age, they will find a greater variety of the bipedal chimp kind of thing until about two and a half million years ago when things kind of changed a bit.
And so we get to Australopithecus, and I know with Australopithecus there are various almost subspecies of Australopithecus found all across Africa. We're still centred in Africa at this moment in time. But would you argue, are they the most successful in the bipedal chimp phase? Are they the most bipedal of them all too?
It's very hard to say because there were quite a few species of Australopithecus. The first one described, Australopithecus africanus, was described exactly 100 years ago, and that came from South Africa. So that was Australopithecus africanus. And so the paleoanthropology world is celebrating that centenary this year.
But there were a number of different species, and whether they were all actually different species or not is a matter of very refined argument. But that genus Australopithecus seems to have been pretty successful throughout Africa. There is another one, indeed, from Chad, Australopithecus bar-el-gazali, which is almost indistinguishable, actually, from Afarensis.
And there's another one in, there's some more in Ethiopia, Australopithecus, but there were some later ones and there were some slightly different ones. So there were quite a few of them. Now, whether there'll be a shakedown and they'll all be the same species or not, or whether there'll be more species, it's very hard to say.
But certainly, as much as anyone has looked between about five and two and a half million years ago, the Australopithecus model of hominin, which is basically a bipedal chimp, was the kind of hominin that existed on the Earth.
It's also interesting that you've got Anamensis, Sediba, Africanus, as you mentioned, all these different types of Australopithecus. Just imagining them walking around, strutting their stuff, maybe the people who left those footprints at Laetoli, as you mentioned, those original footprints found by Mary Leakey and her team.
If it seems that these bipedal chimps, by the time we get to Australopithecus, they're becoming more capable of being bipedal and they're almost walking like we would do, at least for some stages. The big question is why? Why do you think these early hominins, they start becoming more and more bipedal?
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Chapter 5: What are the key features of the genus Homo?
Now, everyone's seen three-legged dogs running along quite happily. But, you know, a one-legged hominin, if you broke a leg, you'd be killed. You'd be eaten instantly by some animal. I mean, I broke an ankle in a trivial accident at home.
few years ago and i was only rehabilitated thanks to the national health service so i was carted off in an ambulance i will have the administration of surgeons and anesthetists and physiotherapists and a wheelchair alone from the red cross and the long-suffering mrs g to pull me to to push me around in it and a circumstance which definitely led although she denies it to her
going back to university to qualify as a nurse, specialising in people with learning disabilities, go figure. But without all these things, I would have died. So natural selection ensured that when hominins started to be bipedal, they had to get very good at it very quickly. Otherwise, so once they started to be bipedal, there was no way back.
And so that's why you get all these bipedal hominins around that time.
It's interesting. It's such a key stage in the story of evolution. And thank you for explaining that there, Henry, the importance of that change in the backbone and bipedalism. So we have got to, let's say, about three, 2.5 million years ago. And it feels like this is when the next overarching phase comes in, the beginning of the genus that we belong to, the homo genus, the homo phase begins.
Yes, 2.5 million years ago or thereabouts was a big change in the Earth climate. It suddenly began to get much cooler than it had been and more seasonal. That's when in the north and far south and in mountain ranges, the ice ages, the sequences of ice ages began to take hold and become more serious. And the result of that was in the tropics,
The forest shrunk further, and something opened up this tropical grassland called the savannah, which opened up. And around that time, two new kinds of hominin appeared. One was called Paranthropus, which was a specialist vegetarian. Now, all hominins before that had been kind of scavengers, omnivores.
Like chimpanzees today, they would have ate all kinds of things, you know, honey from bees, insects. a bit of plants, nuts, seeds, fruits, maybe some other animals, chimpanzees, hunts and monkeys. And so they would have eaten a bit of everything. But Paranthropus became a vegetarian specialist. It had huge teeth and crunched up fibrous nuts and roots.
It's known as the robust one, isn't it, or something like that? Yes, they have been called robust Australopithecines, but they're usually classed in their own genus Paranthropus, and there were several of them. And life for them started hard and just got harder and harder. And they became extinct about half a million years ago. The other genus was Homo. That's the genus that includes ourselves.
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Chapter 6: How did climate change influence human evolution?
They had kind of a bit of a pot belly. And they were good at walking about. But one thing that Homo erectus could do was run. And Homo erectus was a specialist meat eater. It was a social carnivore, much like hunting dogs, and probably behaved in the same way.
Now, a friend of mine, Dan Lieberman, and his colleague, Dennis Bramble, came up with a whole scenario of long distance running as a key feature of the development of Homo. And I'm not surprised. Dan is a very keen ultramarathon runner and runs in bare feet. And he works on human locomotion. So he's really invested in this. But it's the whole syndrome.
One thing that Homo has that you don't have except in other predators such as dogs is a ligament that holds the back of the skull to the neck. So it keeps your head up even without effort. Another thing is if you have a neck and if you have a waist, you can keep running with your arms in contra rotation to your legs. In other words, your left arm moves with your right leg and vice versa.
And you can keep your neck pointed at where you're looking at, whether it's the finish line of the marathon or the antelope you are chasing. At the same time, humans became more hairless. I mean, humans have the same amount of hair, but it's much sparser. And in between, there are sweat glands that most other animals don't have. I mean, your dogs will pant if they're hot.
And animals such as antelopes and cheetahs and that sort of thing, they can run really fast for a short distance. And then they have to stop because they become exhausted and the heat catches up with them. But humans, humans can't sprint very well compared with other animals. But humans are much better than many animals at long distance running. It's the stamina part. Yeah, it's the stamina.
It's the endurance. It's the sweating. It's the hairlessness. It's the... the fact that the human cost of transport, in other words, human walking is extraordinarily efficient. This is why just walking about won't lose you many calories, because it's very, very efficient. Running is slightly less efficient, but humans can manage it mile after mile after mile after mile. So
Hunter-gatherers, when chasing down some antelope, will chase it for a bit, and then the antelope will stop, and everyone else will stop, and they'll recover. And then the antelope goes on a bit, and the humans chase it. But the humans are relentless, and eventually the antelope will just collapse from heat exhaustion. And this is what happens in real life.
And there's also a cooperative element, because as you find in many carnivals, like lions and hunting dogs, they kind of, different individuals head them off and ambush them, and one of them flushes it out while the other one jumps on it. This would have been true for Homo erectus as well.
So the human body shape that we associate with humans today came with Homo erectus, and it seems to have been associated with a capacity for long-distance running that the earlier hominins didn't have, or at least not as well.
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Chapter 7: What significant discoveries have been made in human ancestry?
They may also have been capable of some limited watercraft because there are remains of homo erectus, homo erectus certainly there, artifacts in islands in island Southeast Asia that they could not possibly have reached over land even when there were land bridges joining them.
So Homo erectus was quite inventive and widespread, but not quite the same as us because, you know, Alan Walker and Pat Shipman in their book, The Wisdom of Bones, which is about Homo erectus. So if we looked into the eye of one, we wouldn't see a human. We'd see a savanna predator. They were very much that. They made tools, but they made tools in a quite different way than we would.
And the reason we know that is nobody knows what a hand axe is actually for. So they made hand axes in a very stereotypical way, in the same way that bees make honeycombs or birds make nests. It was a kind of intrinsic thing.
Homo erectus is one of, if not the most successful, I would argue, and longest lasting of early humans, isn't it? And it's a fascinating story. If anyone wants to learn more about the story of human evolution, you start at Homo erectus because it is such an essential hominin to learn about in ultimately the emergence of Homo sapiens and all of that.
And I wish we could cover so many different examples, but Henry set the scene just before the arrival of Homo sapiens onto the main stage. How many different types of early humans are there, and how diverse are they?
Homo erectus, well, you said earlier that, in your opinion, Homo erectus was the most successful hominin, and I would completely agree, because Homo erectus was around from 2.5 million, and the last ones probably died out, maybe 100,000, maybe even more recently in Java. So almost 2.5 million years of very successful hominins.
history, which is an incredibly long time for a mammalian species that's generally lived for only a million years. But by that time, Homo erectus had more or less retired to a comfortable retirement home in Java, and its successors were all over Europe. And some of them were big and beefy. I mean, Homo heidelbergensis, which is probably not a real species, but a kind of mishmash of other ones.
These were big people. There was a shinbone was discovered at Box Grove in Sussex, which is about the size of a large modern male shinbone, but really thick and beefy. I mean, these people could have played for the British Lions. I mean, they were big people. There were some spears, wooden spears found at Schöningen in
In Germany, about 300,000 years old, these were fence posts, and yet they were used as weapons. In East Asia, a marvelous skull was discovered quite recently. There's an amazing story about the discovery of Homo longi, or dragon man. Ah, yes. And the skull, it's only a skull in Manchuria. The skull is at least as big as a modern human.
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