Ancient Human Species We Once Co-Existed With

For most of us, the story of human evolution feels straightforward, inevitable, kind of familiar. If I was to ask you to conjure up in your mind the image [music] that most represents human evolution, it would probably be that much of progress illustration. One species leads to another species leads to another species until eventually we homo sapiens [music] enter the scene and it is game over for everyone else.

Only it turns out that human evolution isn't actually linear. [music] It's much more complicated than that because this is the only time in our species history that only one species of human walked this earth. We previously for tens of thousands of years shared the planet with many, many other species of human. Some were stronger than us, some were tall, some were tiny, some were incredibly [music] smart.

Today, with the help of some of the leading experts in the field, >> you have to remember that you could go your entire life and never make one of these discoveries. not even a piece, not even a tooth. And yet now we're in this period where it's exploding. >> So what we see from this whole fossil record and indeed the genetic record is that human evolution is a process of diversification. >> We introduce you to six ancient human species we once lived alongside, hunted alongside, and in some cases even had children with. [music] From the intelligent Neanderthalss to the island dwarf hobbits to the long-lost Denisvens who gifted millions of us with their genes, this is the real story of the extended human family tree most of us never learned about in [music] school.

A lot of the things that we think make us uniquely human aren't actually unique at all. In fact, some of them we actually got from these earlier species. Now, many of our ancient cousins were so similar to us modern humans, but some were true evolutionary oddballs. So, let's play a game. Which of these species are the most surprising? We'll keep score along the way, and in the end, we will crown a champion.

We're going to cover the gamut. From the birth of paleo anthropology almost 200 years ago when a discovery was made that was so baffling that it took decades [music] to understand its full implications up to the present day which many of us would argue is the golden age of the [music] study of paleo anthropology. The discoveries that are being made today are often baffling and always lead to debate, [music] including about one ancient human species whose behavior is so strange it's still dividing scientists today.

Well, I think the fact that it's there at all, the fact that Fizianis is on this small island isolated suggests that there could be many more examples of species like this to be discovered in island Southeast Asia. So this experiment in human evolution that happened on Flores could have happened on many of the other islands as well. So there could be many more exciting discoveries to come. >> While some of these species may have vanished without a trace, some have legacies that are alive and well. As you're about to see, the homogenous is anything but [music] homogeneous. And the saga of our ancestors is anything but ancient history.

The brains. What separates humans from all other creatures, large and small, that helped us spread to every corner of the world? Now, many would say it's down to our large and complex brains. Homo [music] sapiens, Latin for wise men. I love that we gave ourselves that particular name. But then again, we had mastered fire. We could make stone tools. We built the pyramids. How special are we? For millennia, we have reigned supreme as the last human species [music] standing and also it was long assumed the only one.

All that changed though in 1829, even if no one realized it at the time. That year, amateur scientists entered a cave in Belgium and stumbled upon an unusual skull. Now, the explorers identities are unknown. The significance of their find was utterly lost on them as well. They assumed it belonged to some long deadad person who'd suffered from maybe disease or deformity. Now some historical context. Darwin had not yet published on the origin of the species. That would not happen for another 30 years. The word dinosaur wasn't coined for another decade. And the idea of evolution or for that matter extinction was heretical to the widespread western world view which longheld creation as it is described in the Old Testament.

But then 27 years later, quarry workers uncovered more bones in the Neander Valley in Germany. And this time the world took notice. Long before homo sapiens, a species arose that was in many ways our equal and in others even more than that. Chris Stringer is a leading British paleo anthropologist at London's Natural History Museum. He has spent decades unraveling the story of our species and others. >> So Neanderls, of course, are really the best known ancient humans. We've got a lot of material from sites in in Europe and Asia, nearly complete skeletons and a lot of behavioral information. And what's interesting about them, of course, is they are very evolved humans. >> Homo Neanderthalencis came into its own around half a million years ago. Their ancestors migrated from Africa into Europe and Asia. Their men stood at around 165 cm tall. That's about 5 1/2 ft. So that is shorter than your average modern human today. Although it's more in line with, let's say, Europeans from the Middle Ages. They were strong. They were incredible Ice Age hunters. They traversed long distances. They were probably built for endurance. They had dense bones, thicker muscle mass than most of us. And let me show you their profile. You might think that they [clears throat] have really prominent foreheads. Well, they have very, very prominent forebrows, but the forehead itself, look at it. It recedes. It's actually the opposite of a protruding or prominent forehead, but it's what's behind the bones that you might find most surprising. >> They walked as upright as we do that brains as large as ours. They had complex behavior. >> Brains don't [music] preserve in the fossil record, but the brain case does. And it suggests that Neanderthalss boasted brains very similar in size to our own brains, which seems shocking [music] because if they have big brains too, where are they? >> Not that bigger brains are more intelligent, but certainly with more neural connections [music] and so on, you become a more creative species. >> How might we know this? many potential answers lie in their skulls >> cuz that's that's how we all identify each other. We identify each other by looking at each other's skulls. We don't look at someone's knee and say, "Oh, how nice to [music] see you, Glattus." So skulls have all the clues about who we are. The shape of the Neanderthal skull suggests [music] the region of the brain associated with vision and physical coordination were especially large relative to the frontal lobe which [music] is the area responsible for reasoning. Still, contrary to modern connotations associated with their name, Neanderthalss weren't dummies. >> [music] >> And recently there's evidence that at least 400,000 years ago in Britain, people probably early Neanderals were making fire at the site [music] of Barnum in Suffukk. There are traces of fire. There are traces of stone tools that have been cracked by being in that fire. And there are even pieces of iron pyite. And this is a mineral which we know can be used. It can be struck by stone to make sparks [music] and then give rise to fire. And that iron pyite is not native to the area. [music] So, it's been imported to the site and we think those people were making fire there 400,000 years ago and yet they're not here. So, there's one of that longl lasting questions is, you know, why are we here and not the Neanderthalss? So, why aren't there any Neanderthalss left? The truth is, no one really knows for sure. But our best guess is that they all went extinct around 40,000 years ago. >> But it wasn't long after our appearance in Europe that Neanderls vanished. Uh, was there a tropical disease? Was did we simply uh outbreed them? Was climate change involved that it was getting warmer? >> Did we out compete them? Or perhaps an unspoken alliance was formed? At this point, we simply can't be sure. It is tempting to picture one ancient human species passing on the baton to another. Neanderthalss and homo sapiens, however, coexisted on this earth for over 200,000 years. And we did more than simply cross paths. >> Everyone outside of Africa has a little bit of neanderal DNA in their genomes from ancient interbreeding 40 or 50,000 years ago. >> Everyone with ancestry from outside of subsaharan Africa [music] have about 2% Neanderthal DNA in them. In fact, some people within subsahara and Africa also have Neanderthal DNA. But here's the fun part. They don't all have the [music] same 2%. Collectively, scattered through the DNA of modern humans today, we find as much as 20% of their total genome, a living vestage of a vanished species. Meaning, if someone has ever called you a bit of a Neanderthal, they might actually be right. >> You know, Neanderal is used an insulting term. Politicians with with reactionary policies are called Neanderal. Soccer hooligans are called Neanderal. And I think that's an insult to the Neandals. Um, they were very evolved humans in their own way. Uh, they walked upright as well as we do. They had brains as large as ours. They certainly had many elements of our complex behavior. So, they were certainly not uh the the traditional caveman beastlike image. >> So, how close were they to [music] us? Very. They are our sister species, likely our closest relatives. so similar to us that some of our ancestors interbred with them and many of us are the result of those let's say diances and so when it comes to giving them a score how surprising were they really they were so similar to us that they're not really that surprising at all I'd probably give them a three out of 10 but in of itself the fact that they are so similar to us should blow our minds because to think [music] that an ancient species was so similar to us and no longer is with us is in of itself fascinating to me.

The survivor [snorts] well before the Neanderthalss came the ancestor of them all really the greatest survivor our genus has ever known Homo erectus. Now to be clear they didn't invent bipedalism which is walking upright on two legs. Other species before them were also doing it. But those earlier species were also in the trees. Whereas erectus was exclusively walking upright. >> As Darwin said, one of the cardinal features of being human, which is walking upright. A very strange mode of locomotion. There aren't many bipeds [music] on this planet. But certainly with 8 billion of us on the planet, it's been very successful.

Back in 1890, what began as a hobby for a Dutch surgeon named Eugene Dubois blossomed into an all-consuming passion, one which would change the course of paleo anthropology. Captivated by Darwin, Dubois became obsessed [music] with finding a bridge species from ape to man. He abandoned his career and joined the Dutch colonial army just so he'd be sent to Southeast Asia where he believed his so-called [music] missing link might be found. And as you might have guessed it, he was kind of right. Now, as with the Neanderthal discoveries, skepticism again prevailed. Critics claimed the elongated feur Dubois uncovered belonged to Homo sapiens. But thanks to subsequent finds over 30 years later, Dubois's vision was vindicated. So this is an example of Homo erectus and but compared with us many more primitive features great big brow ridge a smaller brain a very angular cranium and [music] this is one of the really longest lasting of human species so examples of homo erectus are known from Africa at uh [music] more than one and a half million years ago and it seems to have survived as late as 100,000 years ago on the island of Java. So, a very successful species. >> With a track record that long, it is no surprise that Homo erectus claims many potential firsts amongst our ancestors. We think they're the first species to control fire, for example, which is critical, of course, for cooking, warmth, community building, and warding off predators. The excavation of a site inside a South African cave dating back 1 million years revealed evidence of [music] a repeated series of small fires all in the same spot. >> But in those early stages probably people were [music] capturing natural fires perhaps from volcanic eruptions perhaps from natural forest fires perhaps from [music] lightning strikes and they were then keeping that fire going as long as they could. But it took a long time, it seems, for people to develop the ability to make fire at will. >> Her erectus may also be able to claim the first major innovations of stone age technology such as handaxes and possibly [music] possibly also Earth's first artwork. The disappearance of Homoctus and other ancient human species just as Homo sapiens were coming into their own does seem to support this idea that we [music] simply out competed them. But a lot of research indicates that it is a much more complicated [music] and nuanced picture than that. >> So the pattern of human evolution overall for millions of years has been a diversity of species uh living at least in proximity to each other if not in exactly the same places. So there's all that diversity which is typical of the whole of human evolution until this last 30,000 years when we're left alone on the planet and [music] we're the only survivors of all these experiments in how to be human. We really don't have the answer. We don't know if our species got lucky or whether there was a real element of, if you like, superiority in our brains or our behavior that led us take over the planet and cause these other species to die out. So, it's still unclear to what extent we were responsible for the extinctions directly [music] of these other human species. In the case of Hermerectus, it's possible they failed to adapt as the grasslands in which they had flourished grew into less forgiving jungle. Or maybe [music] they failed to compete with smarter species capable of fashioning more advanced tools and formulating superior hunting strategies. But maybe, just maybe, after their enormously long day in the sun, 2 million years on this planet, that's 10 times longer than we homo sapiens have existed on Earth. Maybe it was simply their time. So, in [music] conclusion, how similar were Homo erectus to us? Well, if they hadn't have perfected their posture, our lives would be very, very different today. In fact, it's not just us that owes him that huge debt of gratitude. We think that many of the other human species that were around at the same time as us were also descended from that species Homo erectus. And it makes you think they are kind of remarkable and surprising. They make sense in terms of their place in the evolutionary tree. That longevity is slightly bonkers. And so I would probably give them a 6 out [music] of 10.

The builder. Across the ancients, we find many reoccurring achievements using fire, for example, and making tools, but Homer Hydroenzis may be able to claim the achievement of the first homes built by human hands. >> So, Homer Haidobensis, and I've got an example here of from Cabway or Broken Hill. This is a replica of a fossil that was found back in 1921. >> In 1907, a German quarry worker happened upon a massive jawbone. An anthropologist determined this oversized and mostly chinless mandible belonged to a species distinct from any yet known. Naming this human ancestor after the town which it was found in, the so-called H Highleberg man, aka Homo Hidleberenis. The history of Homohyleberenzis may stretch back as far as 1.3 million years, but conservative estimates place their dawn closer to 700,000 years ago. The Homo H Highleberg male stood a relatively strapping 175 cm or 5'9. Compared to the earlier Homo erectus, the brain was larger, approaching modern human proportions. >> It's more derived than erectus, a larger brain, a more expanded cranium, but also still some primitive features. So the back of the skull has this strong ridge of bone like erectus with angulation and the cranium is not so expanded and filled out as it is in us or or neanderals. So a mixture of features and this seems to have been a very successful species certainly complex behavior in hydrogensis perhaps not as complex as ours or neanderals or longi but certainly more complex than erectus. Proof of Homer H Highleberg's complex reasoning and physical abilities lie most dramatically in how they address the need for shelter. >> In terms of behavior, we think that Hydeensis did have complex behavior. The brain is certainly approaching the levels of of people today and Neandertos um and we look at something like like this and we've got examples of Haidobensis even from Britain uh probably from the summit of Boxgrove from about 480,000 years ago. Homoid Beenza's homes may have been built with wooden poles or bones fixed in place by heavy stones [music] and we think they were covered with animal hides or branches. One H Highleberg's community discovered in Germany and approximately [music] 400,000 years old may have even featured fences perhaps to keep large predators out or to contain freshly captured game until it was time to feast. Homo had begun may have [music] been the first big game hunters. >> And there we've got evidence that these people were able to hunt actively horse, deer, probably even rhinos. They were butchering all these animals at the site, making uh beautiful hand axes and then systematically dismembering these carcasses, getting all the meat off of them in what was a dangerous landscape with many dangerous wild animals around. So they were kind of possessing that carcass and fully in control of that local environment. >> Homo hydroleenzis migrated [music] throughout Europe. >> Opinions differ about what's in haidensis, how widespread it was, but in my view, hide against was a long live species. It was present in Europe and Asia and Africa. >> Their trail goes cold some 200,000 years ago. And the usual suspects may well apply. Climate change, food scarcity, disease, competition. But some scientists would argue that their story never ended because for them hidelenzis may have given rise to the Neanderthalss [music] and us. So in terms of how similar they are to us, well if they were our ancestors, very similar. But H Highleberg is in many ways a [music] mystery because were they our ancestor or weren't they? [music] So, in conclusion, when it comes to how surprising of a species are they, well, they were capable. They were not primitive, but it would be nice to know if they were our grandparents. So, I give [music] them a seven out of 10. >> And also, it provides a kind of evolutionary bridge between the more primitive erectus and the more derived humans, us and Longi [music] and Neander.

The Hobbit. Up till this point, we've covered what might be called the first golden age of paleo anthropology. So from the mid [music] 19th century through to the turn of the 20th century, scientists had unearthed and analyzed evidence proving that homo sapiens both sprang from and once shared the planet with other [music] human species. But then the new century brought in the second golden age of paleoanthropology with miniature skeletons, DNA bombshells, and possible mysterious rituals. And it all kicks off in 2003 when paleo anthropology leaped back into the headlines with some very big news about some very small humans. Meet Homo Floresensis, aka the Hobbit. >> So Homo Floresensis is a remarkable species. um homophoresensis suggesting it's genus homohouan although I'm not sure it really is. Um but this is a really tiny species. This is the cranium. It has an apesized brain there. The whole [music] skeleton suggests these individuals. Some of them were barely more than a meter tall as adults. So this is very smallbodied small brain. So it looks like a completely separate line of evolution that evolved [music] there for hundreds of thousands perhaps even a million years. Inside a cave on Indonesia's Flores Island, a joint Indonesian on Australian research team was stunned to find a nearly complete and extremely petite skeleton of an adult female who lived and died about 80,000 years ago. The typical adult homoizenzis stood on average of 3 and 1/2 ft tall. So that's about 105 cm and weighed all of about 30 kg or [music] 65 lb. The origin of this species of course is still unknown. Some people believe it's a dwarf form of Homo erectus. So it may have come from somewhere like Java. But others and that includes me think that it's something much more primitive. It may be a relic of a group that spread into the region maybe 2 million years ago and then evolved for a long time in isolation. Homo floresensis was likely pintsized because of this incredible phenomenon known as island dwarfism which basically means that on an island the large animals get smaller thanks to a reduction in resources but weirdly the small things on the island get bigger because [music] there are less predators on that island. Homo floresientists challenges many of the assumptions about ancient [music] human species not only in regards to their physical stature but in their brain size and therefore brain power and capabilities. Now we typically equate brain size with intelligence and we humans are supposed to be intelligent and yet somehow homophorizes has a brain the size of the brain of chimpanzees and yet they were able to make stone tools. So really it does challenge what we think it is to be [music] human. >> So I think that in terms of its behavior homo floresensis was much less like us. [music] I think it although it's using stone tools I think its way of life is much simpler and I think it really wasn't showing the complexity of behavior that we find in us in the Neanderles. >> How and why did homophoresensis disappear 50,000 years ago. So it turns out they weren't the only striking and exotic species on the island of Flores. So from what we know of Florizens, yes, it was using stone tools and it was eating meat and obviously plant resources as well, but it may well have got much of its food from scavenging the kills of Komodo dragons, which were the main predator on the island of Flores. [music] >> In addition to those giant lizards, there were also species of giant stalks and giant [music] rats. And if it was acquiring its own food by hunting, it probably was getting things like giant rats and much smaller beasts than the large animals on the island. >> Homophoresensus' diet may also have depended on a another island um creature, a rather remarkable elephantlike mammal called a stegodon that on this island was so small, so dwarfed that it was the size of a cow. And so you have a human the size of a 4-year-old hunting elephant-like creatures the size of cows on this island. The stegodons died out, possibly even hunted to extinction. And when that happened, the problem it presented for homo floresiansis might have [music] been anything but small. Now we're not sure why homopesis went extinct. The stegodons might have been a contributing factor, but volcanic eruptions do look like they were incredibly detrimental. It's also possible that we were a final nail in the coffin. And the final question, how surprising are they as a human species? >> So I think for Floriziansis, of course, there's the whole question of whether it is human. The name Homo Floresensis implies it is, you know, a member of the genus Homo, which I call human. But in fact, many of its features are much more primitive, more apeike. It suggests it was probably still spending time in the trees. In many ways, I doubt that it really is showing human features in the way that say Neandertos or Holongi are showing human features. >> Well, they're humans the size of fouryear-olds making stone tools and hunting elephant like creatures on an island. [music] So, I'm going to go for a 10 out of 10 for surprising or an 11 out of 10 or 100 out of 10. [music]

The Enigma. So if it wasn't for modern DNA analysis, it is not clear when we would have discovered the Denisven, a remarkable species that does blow my mind. >> So I've got here a replica of the harbing cranium and we're pretty sure that this is the most complete fossil of a denisan that we've got. >> So in 2010, a bone, a finger bone to be precise, was sent off for analysis in a German laboratory. Now this particular finger bone came from a Neanderthal in Denisa cave in Siberia and they crushed it up to analyze its DNA [music] only they extracted its DNA but it wasn't Neanderthal DNA that they found and it also wasn't homo sapiens DNA but it was human DNA. So it turned out that this fingerbone belonged to a human that was as yet an undescribed unknown species to science but it was human. And so the question was who were the mysterious Denisans? The analysis of Denisven DNA showed that their DNA is inside many many modern humans living today. In fact Tibetans who are able to live at very high altitude are able to live at high altitude. Turns out because of a mutation that they picked up off Denissance. [music] >> So these people were widespread across eastern Asia, very successful living in a range of environments up in northeast China, [music] in Siberia, up on the Tibetan plateau. And from their DNA, we think that they were also down in places like Ireland, Southeast Asia. [music] >> The big question remained, what did the Denisans actually look like? Because we didn't really have a fossil for them. Now there was one part of a jaw that [music] was found in Tibet by a monk and upon further analysis [music] it turned out to be a denissant but it was only a part of the jaw. It wasn't the full face. [music] >> It is very much like one of those detective shows seeking evidence and trying to identify clues [music] that will allow us to interpret the lifestyle or the anatomy of these creatures. [music] And so the mystery continued. It became almost like the golden chalice was the holy grail of paleo anthropology. [music] What did the Denisans look like? And then another discovery was made in Denisa cave. Again, a bit of bone was analyzed and it was found [music] to have a Neanderthal parent and a Denisven parent. And so we effectively had a hybrid individual. Now they called this girl Denny. But again, we still had no [music] face for the Denisven. And then in 2001, a skull [music] was analyzed that they called Dragon Man. Now, there is a whole story behind this skull. It was apparently found at the bottom of the world, but some people question this [music] story cuz it goes all the way back to World War II. But when they did the analysis, they were able to confirm that it was a new species [music] called Homo Longi. But when they did the DNA analysis, they were able to confirm that it was also [music] a Denisven. So we finally knew what the Denisans actually looked like. By the way, [music] they looked a bit like Neanderthalss, but perhaps a bit more robust, a bit kind of more rugged, shall [music] we say. And so when it comes to how similar they are to us, honestly, like the Neanderthalss, their DNA lives on in many, many of us walking around today. The denisan seem to have been capable of living in very cold conditions in high altitude conditions and also down in the south of Asia and island Southeast Asia in tropical and subtropical conditions. So for example, it seems to have helped populations adapt to high altitude conditions in Tibet and down in island Southeast Asia. It's certainly part of disease protection uh down there helping the immune systems. So they're incredibly similar to us because clearly [music] our ancestors were at times frolicking with the Denisven. They're also very similar to us in many kinds of [music] uh technology and behavior. But when it comes to how surprising of a species they are, a species that was discovered from its DNA, I'd give that a solid 8 out of 10 for surprising.

The mourner. Now on first glance our final species may appear primitive compared [music] to modern humans but in homonyi we do find an echo of an attribute that is decidedly us. >> And here we've got examples of homonyi. So this is a really interesting species. We've only known about it in just really the last 10 years or so. >> They were in South Africa 2 to 300,000 years ago. Their history may stretch back as far [music] as 2 million years. They are yet another thread in the tangled web of the so-called muddle in the middle. A phrase which we use to describe many different human species that existed in the middle plea scene whose relationship with each other and with us remains very unclear. The discovery of Hermoni is worthy of Hollywood. It begins in 2013 near Johannesburg inside the cradle of humankind. A world heritage site and as the name implies an established paleropological hotspot. A group of explorers spotted a narrow opening inside a cave which they discovered offered a small entrance [music] to a hidden chamber. Inside it the largest collection of a single homminin species ever found in Africa. One that lay undisturbed for hundreds of thousands [music] of years. Enter paleanthropologist Lee Berger. >> It had instantly become the richest fossil homminate site discovered in all of history on the continent of Africa, perhaps in the world. working in confines so claustrophobic only a team of small pale anthropologists known as underground astronauts could negotiate [music] them. The remains of at least 15 ancient humans were painstakingly recovered. Hermani was small. Adult males stood at about 5 ft tall. So that's 150 cm. [music] On average they weighed about 100 lb or 45 kilos. >> Like homophorizensis it's got very small brain. This is an apesized brain here. And yet the teeth show, you know, quite derived features. They're quite small. [music] The diet seems to have been very humanlike. And yet this is a small brain creature with a skeleton that combines some humanlike features in, for example, the legs and the feet and the hands, but also some much more primitive features, suggesting that the creature was still spending a lot of time climbing uh maybe up on rocks, but also up in trees. >> While hermoni brains were not much larger than a chimps, they were asymmetrical. and the frontal loes were elongated each in ways that recall another species, namely [music] us. Some controversially believe that homeowner practice behavior previously thought to be unique [music] to modern humans and perhaps Neanderthals, symbolic and ritualized disposal of [music] the dead. A possibility which it turns out offers the suggestion that brain shape may [music] ultimately trump size. Now, given the location of those fossils, remote and hard to reach, a tantalizing theory holds that fellow homei intentionally put them there. Perhaps as a way of paying final respect. Is it possible these ancient and seemingly primitive creatures had a fully developed concept of a soul of an afterlife? >> It's claimed that Hommoni was engaging in very complex behavior, burying its dead, engraving the cave walls, and building fires deep in the cave. And that is still the subject to a lot of scientific debate. So I think for Homundi, one of the outstanding questions is how complex was its behavior with that small brain? And I think some of us really doubt that it could have had such complex behavior with basically an ape oropithesine sized brain. Um, and I think it really will be a big test of of of the whole question of why we have big brains because it's assumed, you know, brains are energetically very expensive. And it's assumed that evolution drove the development of larger brains along with complex behavior. Um, and if Nledi shows that complex behavior with such a small brain, it really raises the question of of how Nledi could even do that with that small brain. Lee Burgerer is more convinced on the idea that homeowner Lei deliberately buried their dead. Here he discusses what he sees as a clue, one left for us some quarter of a million years ago. Discovered in the deepest recesses of the rising star cave system. This little child's skull is a great mystery. It's found in one of the most inaccessible places and it's there alone. There are no parts of its body. There are no parts of its mandible. It's just [music] a skull and it appears to have been placed on a ledge in a place that's probably the most difficult place to get in the entire rising star cave system. Uh so it's a great mystery and we think possibly several hundred thousand years ago a homonyi placed that child's skull there. >> Burger notes that in his experience one rarely finds bones of any one species without finding remains of others close by. During the expedition itself, only hominids were coming. There's always other stuff. There was no other stuff. They were alone. >> If Burger is correct, the implication could hardly be bigger. >> We've already claimed that this is a site of deliberate bodies disposal. What I think a lot of people may not really understand is if that's true, then Homoleti is already operating at a level that we're not claiming for Homo sapiens for another 200,000 years. [music] It's already operating at a level that borders on the symbolic likely. >> Why might Home and Ali have ritually buried their [music] dead? For the same reason we still do today. >> Why? Cuz we spend all our time trying to explain why we're separate from [music] nature. And so did our ancestors. And all of them did it in the past. They saw themselves as separate from nature and separated. They didn't want bodies going undergoing those >> [music] >> uh natural processes for whatever reasons. And that does vary. But it's almost a universal truism in human behavior into the relatively deep past where we know they're humans. So if it's true in homonyi, then it's astounding. [music] Beyond questions regarding potential burial practices, many other fundamental mysteries remain surrounding homonyi. [music] >> The questions that we all have. Is homonyi related to us? But did homonyi ever meet [music] Homo sapiens? Or maybe more appropriately, did homo sapiens ever meet homonyi? And if so, what happened? We don't have an answer for that yet. Is Homonyi that elusive species X that interbred with modern humans in Africa around 200,000 [music] years ago? Is homonyi another thing that is related to us and not species X? And how is it [music] related to us? Is homttleti not related to us at all? That would almost be more remarkable. And yet homonyleti is so primitive. It would be remarkable. There's no no answer that's not going to be striking within that. >> The bad [music] news is the answers to many of our questions are as yet unknown. The good news, as only small sections of Hermoni's caves have been excavated, there's reason to hope the answer [music] to this and many other mysteries still waits us inside their walls. If it could hide from us, if it could remain and invisible from us [music] for likely millions of years as it existed in parallel to all these other things we're finding, other things could too. There's more out [music] there to find. >> We asked the question one final time, how close were they to us? A potentially well-developed spiritual side helps their case immensely. However, whether they really did have a spiritual side is one of the most hotly debated questions in the field, which helps me when it comes to [music] scoring how surprising of a species they are. Because if they are doing that, tiny brains practicing spirituality or shamanism, that is a 9 and a half out of 10 for me.

When it comes to the homogenous, that which unites us all may ultimately trump that which made [music] each ancient human species unique. But in conclusion, which species is the most surprising? Denisven, sure. NDI, why not? Homo floresiansis, the hobbit, definitely. But perhaps the most surprising is that they existed [music] collectively alongside us. And which ultimately of all of these species bears the closest resemblance to our species, [music] it would probably be between the Neanderthals and the denissipants. Now, [music] in each of the ancient species with whom we once shared the planet, we see elements of ourselves. Some, like the Denisvens and the Neanderthalss have been shown to literally live on in contemporary human DNA. [music] And as research and genetic testing improves, it's likely others will join their ranks. >> So, I think the evidence suggests that we and the Neanderles and Homolongi diverged probably more than a million years ago. Our Linges went their separate ways. Neander was evolving in Western Eurasia. us evolving in Africa most of the time and the longe denisman lineage evolving over in eastern Asia but now and again these lineages came together and did some interbreeding and certainly within the last 60,000 years as homo sapiens spread more widely there was distinct episodes of interbreeding with neanderals in the west that was then carried around the whole of the rest of the world as as homo sapien spread but also over in the far east and island southeast Asia there were separate phases of interbreeding with different groups of denisants and that DNA is found in humans today. >> Our genetic connection to the ancients is far more than academic. Interbreeding provided benefits for all parties involved. >> So what we see from this whole fossil record and indeed the genetic record is that human evolution is a process of diversification. And we've got these branching patterns of [music] species diverging from each other, adapting, developing different behaviors, developing [music] adaptations to live in particular environments, but it wasn't a complete separation because these branches now [music] and again in some places came together and exchange DNA. And this is a pattern we see today for closely [music] related species that they'll go their own way, but now and again, if they get the [music] chance, they will interbreed with closely related species and pick up a bit of diversity that they may have lost or [music] perhaps acquire some bits of DNA that are good for them that they hadn't yet evolved. With new DNA studies, what we're find out is they don't [music] all disappear. There's almost always some small introgression of DNA that gets captured by homo sapiens. And maybe that's our trick. Maybe we just keep breeding oursel into the better mousetrap. [music] >> The effects of ancient interbreeding can still show up in ways that surprise [music] us. >> It seems that some of these bits of DNA are linked with autoimmune diseases [music] in people today. And down in Ireland, Southeast Asia, it's certainly part of disease protection uh down there helping the immune [music] systems. Associations have been found with Crohn's disease, CO 19, immunities, and even addiction. [music] Ancient humans remain relevant to modern life. The past is never really gone. Given the [music] recent explosion of groundbreaking new discoveries, at least three possible new species have already been discovered in this very young century. So, who knows what or who else is still [music] waiting to be found.

Well, I think the fact that it's there at all, the fact that Ferosiansis is on this small island isolated suggests that there could be many more [music] examples of species like this to be discovered in island Southeast Asia. So, this experiment in human evolution that happened on Flores [music] could have happened on many of the other islands as well. So, there could be many more exciting discoveries to come. The only thing we [music] absolutely know is that we're alone today. >> What else will we learn about our ancient ancestors? And what more can this tell us about ourselves?