Alien From Earth

Alien From Earth

PBS Airdate: November 11, 2008

NARRATOR: It is the dream of every archaeologist who slogs through backbreaking days of excavation, the find that changes everything.

ABC NEWS REPORTER (Archival Footage): A team of Australian and Indonesian archeologists has discovered the remains of what's believed to be a new species of human.

HENRY GEE (Nature Magazine): This is a major discovery.

CHRIS STRINGER (Natural History Museum, United Kingdom): It implies we are missing a huge amount of the story of human evolution.

NARRATOR: Paradoxically, the discovery is huge because its pieces are not: a skeleton of an adult, the size of a three-year old child; a skull one-third the size of a modern human's. Could a race of tiny creatures, soon nicknamed "hobbits," have thrived at the same time as modern humans?

To many, the evidence is irrefutable.

BILL JUNGERS (Stony Brook University): This is not a little person. Absolutely, we're looking at a new species.

NARRATOR: But some scientists just aren't buying it.

RALPH HOLLOWAY (Columbia University): It just invites tremendous skepticism.

JAMES PHILLIPS (Field Museum of Natural History): I don't believe it.

MACIEJ HENNEBERG (University of Adelaide): There is only one skull, so that's not a proof of anything at all.

NARRATOR: So is the hobbit a momentous find or a career-wrecking blunder? The answer may overturn our understanding of how we became who we are.

PETER BROWN (University of New England): I think we may have to rewrite the human evolutionary story. At the present, every textbook on the planet is wrong.

NARRATOR: An astonishing discovery, a bitter controversy.

CHRIS STRINGER: In this situation, one group of people are going to be 100 percent wrong, so it really is quite an extreme case.

NARRATOR: And now, four years after the unearthing of the hobbit, new evidence that may finally solve the riddle of its existence. Alien from Earth, up next on NOVA.

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NARRATOR: The Indonesian island of Flores is home to an ancient legend. It tells of an elf-like creature with oversized feet, an awkward gait and a voracious appetite. Villagers call her "ebu gogo," "the grandmother who eats anything."

She seems as mythical as all the other tiny beings found in fairytales and big Hollywood films, creatures like leprechauns, elves and hobbits. But is she? Were the storytellers of Flores inventing or reporting?

The first evidence of what might be a new human ancestor came to light in the 1990s. While searching for fossils, a team of Dutch and Indonesian scientists uncovered puzzling artifacts.

These rocks may look ordinary, but to a trained eye, their sharp edges stand out. They are handcrafted and so old, modern humans could not have made them.

CHRIS STRINGER: I was certainly a skeptic to begin with. Were they really stone tools? Were they in the deposits they were said to be in? Were they dated to the right time?

NARRATOR: Archeologist Mike Morwood was asked to examine the tools.

MIKE MORWOOD (University of Wollongong): There were indications that they were at least 700,000 years old. So that started off my first association with Flores.

NARRATOR: Tools this ancient should not exist on Flores. For millions of years, it's been cut off from the Asian mainland by the Wallace line, a bio-geographical barrier formed by deep ocean trenches.

For eons, the line's treacherous currents have barred most animals from crossing over, and kept those who did so isolated that evolution worked some remarkable changes. One that survives today is the carnivorous, poisonous Komodo dragon. At 10 feet long and 300 pounds, it's the world's heaviest lizard.

As for seafaring modern humans, there is no evidence they reached Flores until about 12,000 years ago. So who made the mysterious stone tools three-quarters of a million years old?

To figure out the identity of the ancient toolmakers, Morwood and his colleagues needed more evidence. Their search took them to a limestone cave on Flores called Liang Bua. In the local language the name means "cold cave."

With its cathedral ceiling, it has long provided a refuge from the tropical heat and rain.

MIKE MORWOOD: My first impression was that this is the best archaeological prospect I have ever seen in my 30-year career.

NARRATOR: The explorers hoped the cave's sediments, built up over millennia, would contain secrets from the distant past. But before the dig could begin, the team needed to figure out how to prevent the walls from caving in.

BERT ROBERTS (University of Wollongong): So myself and others went on a grave-digging course in Sydney, to learn how to safely shore up soft sandy deposits. And we needed that for Indonesia because we're going 16, 17 meters underground. You need to make sure that things that are dropping in, coming in on your head, aren't going to actually...it's not going to happen, otherwise, you'll end up dead. So everything has to be properly shored up if you're going to go down to these sorts of depths. And nobody had done that in Indonesia.

NARRATOR: For two years they dug deep pits, removing tons of sediment, sifting every bucket-load, looking for the ancient toolmakers.

Then, about 20 feet down, they discovered a tiny arm bone.

MIKE MORWOOD: Our bone identification person was just totally puzzled by it. It was that different, a single bone, very unusual and very small. We didn't know what to make of it.

NARRATOR: Another year of exhaustive digging yielded little else except a single, possibly-human tooth.

With money running out, Morwood briefly left his Indonesian colleagues, Thomas Sutikna and Rokus Awe Due, digging at the site.

MIKE MORWOOD: A couple of days later, I phoned them up, and Thomas said, very excitedly, "We have the skeleton of a pre-modern individual." It had no forehead, it had significant brow ridges, it didn't have a chin, and so on.

NARRATOR: An apparently pre-human skeleton was a tantalizing find. Its small size and shape suggested a female child, but Rokus soon discovered wisdom teeth, exposed and worn. This skeleton was not a child, but a miniature adult. If she was human, she was one of the smallest adults ever found, barely three feet tall.

Struck by her size, the team classified her as a new species: Homo floresiensis. They labeled her skeleton LB1, for Liang Bua, but it was the name of a fictional character that stuck: the hobbit. And she was not alone.

The team also found fragments of twelve others, equally tiny, including a complete lower jaw. Surrounding them were stone tools, charcoal and the butchered bones of pygmy elephants, suggesting, incredibly, that these tiny creatures hunted and used fire.

BERT ROBERTS: This was something completely out of the sky, seemed to land straight in our hole. But it was genuine, it was real, and now we've got to deal with it.

NARRATOR: To explain these puzzling discoveries, Morwood turned to Peter Brown, an expert in paleoanthropology. The hobbit took him by surprise.

PETER BROWN: Within 60 seconds I realized its lower jaw was totally outside the range of modern human variation. There's no way it could have been a modern human. It was very, very clear cut.

NARRATOR: The most perplexing feature of the hobbit was its tiny brain, smaller than a chimpanzee's.

PETER BROWN: When I first measured the brain volume of Homo floresiensis, my colleagues reported that I went into a sweat, got very, very flushed and was obviously flabbergasted. So I re-measured it, re-measured it, re-measured it. It just didn't make any sense.

NARRATOR: The hobbit brain is dwarfed by a modern human's: At around 400 cubic centimeters, it's less than one third the size. Although her skeleton was surrounded by tools, she seemed to be a throwback to a primitive ancestor.

CHRIS STRINGER: If it is what it is, what seems to be, it's an extremely primitive, human-like form. It has a brain the size of chimpanzee, yet associated, apparently, with stone tools, living in a place where we never knew primitive humans got to, so altogether a very challenging find.

NARRATOR: To make sense of the discovery, the team needed to know how long ago the hobbit had lived. Bert Roberts set out to date the sediment layers surrounding the ancient fossils.

BERT ROBERTS: My specialty is luminescence dating. That's where you look at when the sediments were last exposed to sunlight and entered the cave. And that's great, 'cause then you can work out the burial age of the individual. So straight away we started working on the sediments surrounding LB1, and we came up with a date of less than 30,000 years, which was very surprising.

NARRATOR: If Roberts was right, the hobbits lived recently enough to have co-existed with modern humans. That surprising result opened up the possibility of using another method, radiocarbon dating, to fix the age of the bones even more precisely.

Morwood sought out Chris Turney, an expert in radiocarbon dating.

CHRIS TURNEY (University of Exeter): There were these stunning ages, going back in time, and the main hobbit was the equivalent of 18,000 years. I was over the moon, blown away. I was desperate to go and tell everyone, but I couldn't, because none of the other team was there. And then when the other numbers started coming in, we just thought, "God, these must be real." This was a creature who outlasted Neanderthals in Europe, that was kicking around the doorsteps of Australia, at least 13,...10,000 years ago.

NARRATOR: The bones were between 10,000 and 95,000 years old. These surprising dates challenged the conventional picture of human evolution.

The standard view based on fossil discoveries and genetic analysis has held that about 6- to 7,000,000 years ago, a new kind of animal split from an ape-like ancestor and gave rise to other species, upright like itself. Called hominins, these ranged from small-brained australopithecines–like the famous Lucy–to tool-using Homo habilis–nicknamed "Handyman" –and the first migrant out of Africa, Homo erectus, who journeyed as far as Indonesia, 1.8 million years ago. A million years later, Homo neanderthalensis, the most human-like, had spread across Europe. All eventually perished, except our own species, Homo sapiens, which arose in Africa some 200,000 years ago.

NARRATOR: Ralph Holloway has spent much of his career placing fossils in the timeline of evolution. For him, the small-brained hobbit posed an immediate problem.

RALPH HOLLOWAY: The brain size has almost tripled in the course of human evolution. If we try and take Homo floresiensis and put it in the timeline, we're going to move it up here, right before we come to Homo sapiens. And to find a new species with a brain the size of chimpanzee is really an extraordinary detail that does not seem to fit with anything we know about human evolution.

HENRY GEE: When people discover a fossil, they have enormous expectations about what that fossil can tell us about evolution, about past lives. But fossils actually don't tell us anything, they are completely mute. The most they are is an exclamation that says, "Here I am, deal with it."

PETER BROWN: And so you're working through, in your own mind, ways to try and explain what is essentially unexplainable. If the remains of an alien spacecraft had been found in central Flores, I would have been more accepting of that than I would of this particular fossil. It was in the wrong place at the wrong time.

NARRATOR: So what were scientists to make of the small-brained hobbit found in this remote corner of Asia? And if it was a new species how did it out-migrate and out-survive hominins far more sophisticated?

Just as the discovery team began to search for answers, the priceless bones were taken away. Teuku Jacob was regarded as Indonesia's grand old man of paleoanthropology; no one could refuse his request to examine the hobbit.

BERT ROBERTS: That was really disappointing. I thought that people in Jakarta were looking after our interests, and then it turned out that, behind the scenes, the bodies were getting stolen out the back door.

HENRY GEE: The unwritten rule of paleontology is that people who discover a bone should be able to be given as much time as they need to describe it, and it's not right that people should just take it away. That's actually quite unethical.

NARRATOR: Jacob analyzed the skeleton and declared it was most likely the remains of a modern human pygmy.

TEUKU JACOB(Paleoanthropologist): So everything is the direction of Homo sapiens. And I'm sure about it.

NARRATOR: Eventually, Jacob returned the bones, but by then the dispute had brought the excavations at Liang Bua to a halt.

Although the digging had stopped, the battle over how to classify the hobbit had just begun.

CHRIS STRINGER: If we define humans as tool-making and tool-using, then potentially it's human; walking on two legs, then it's human. But if we define humans by being large-brained, then it isn't human.

NARRATOR: To account for the hobbit's small brain, the skeptics offered a simple solution.

MACIEJ HENNEBERG: The most logical conclusion is that this is something modified by a disease.

ALAN THORNE (Australian National University): That's probably the ultimate answer to this whole thing. It's about a pathological specimen.

NARRATOR: In Paris, there is a famous example of just such a pathology that prevents the growth of the brain. Called microcephaly, it is a rare condition often caused by defective genes.

This is Bebe, an 18th century court jester who amused European nobility. Fully grown, he was three feet tall, with a head smaller than the hobbit's.

So was the hobbit a human suffering from microcephaly? The answer is being pursued in St. Louis, at the Mallinckrodt Institute. By taking CAT scans of the hobbit's skull, radiologists can recreate a model of its brain. Anthropologist Dean Falk compares it to the brains of microcephalics.

DEAN FALK (Florida State University): We put together a sample of 10 individuals from different parts of the world who truly were microcephalic. They had very small brain sizes, some of them as small and even smaller than hobbit's.

The CAT scans show that hobbit and the microcephalic look totally different. The frontal lobe of hobbit is swollen underneath and expanded. But in the microcephalic it's sharp and flat. And in the microcephalic, as is typical for them, the cerebellum is pushed way, way back, so...dramatic differences.

NARRATOR: One of the greatest contrasts between the two brains lies in the frontal lobes. In microcephalics, they are underdeveloped, so victims often have unusually pointed heads. The disorder can cause mental impairment.

DEAN FALK: We don't think hobbit, by any stretch of the imagination, is a microcephalic. The brain shape is totally different. It's the right size, just totally the wrong shape.

NARRATOR: But were there signs elsewhere in the skeleton that pointed to pathology? To find out, paleoanthropologist Bill Jungers spent two years examining the hobbit.

BILL JUNGERS: Yeah, there are some bumps and bruises. There's some little bony growths in some of the foot bones that indicate there could have been a slight trauma, but there's nothing in this skeleton that suggests that this was a sick hobbit.

NARRATOR: But could a small-brained hobbit have made the stone tools found at Liang Bua? To many, they seem clearly the handiwork of larger brained hominins.

JIM PHILLIPS: What is important is the brain and eye-hand coordination and the idea of making something. You have to select the specific kind of raw material; you have to prepare, really prepare this core or this pebble before you even begin knocking off the blades. If you prepared it right, you can just go like this, one after another. So the brain is the important element. And a 400-c.c. brain, in my opinion, is not going to be able to produce, repeatedly, a tradition both of blade and flake technology.

NARRATOR: But to others, the evidence is less conclusive. Mark Moore has been studying the tools found around Liang Bua.

MARK MOORE (University of New England): One of the best ways to learn about stone tools is to go try and make them yourself. Now Jatmiko and I have came down to the gravel bars of Racang to look at the problems that Homo floresiensis faced in producing pieces that she could use small enough to carry, from these really quite large stones we have here in the gravel bar. So we are going to try ourselves.

Now, as I've produced these flakes, you can see that they're very sharp-edged. And it's these flakes that Homo floresiensis was after, because she could use the edges as really effective tools for processing wood, cutting meat, anything that she happened to need to do in the cave.

The stone tools at Liang Bua are extremely sophisticated, in the sense that those hominids were very good at knapping stone. They understood all the geometrical aspects of where to strike the stone, how to follow the high mass on the ridge of the core to make sure you get off decent flakes. They were very, very good at that. And in that sense, these stone tools are very sophisticated.

NARRATOR: But how do the tools at Liang Bua compare to those made by ancient, small-brained hominins in Africa?

Moore found the knapping techniques were quite similar.

MARK MOORE: So, if a small-brained hominid could make those sorts of tools in Africa, there is no particular reason why a small-brained hominid could not make the stone tools that we see at Liang Bua cave.

NARRATOR: And perhaps brain size alone isn't the only measure of intelligence. Although the hobbit's brain is smaller than a chimpanzee's, Falk notices dramatic differences.

DEAN FALK: Over the entire surface, there were special features that you don't see in chimpanzees. And that was a surprise in and of itself. There are these two convolutions right in the front of the frontal lobe that are huge. And we see small traces of those convolutions, at times, in chimpanzees, but they are very small.

NARRATOR: These protruding frontal lobes expand a part of the brain believed vital for higher thinking and planning ahead.

DEAN FALK: It made my team think that maybe we had hit upon part of the answer of, "How could such a little creature with such a small brain have done the activities that the archaeologists had attributed to it?"

NARRATOR: Activities such as hunting the elephants whose bones now litter the Liang Bua site. True, these were pygmy elephants, smaller than some cows, but even so, quite a challenge for beings the size of three-year-olds.

BERT ROBERTS: The brain suddenly pulled it all together into one beautiful coherent whole. This was a person who could hunt effectively, could obviously cross water barriers, could communicate, possibly well enough to hunt a small elephant. They still weigh half a ton; you're not going to tackle one of those by yourself.

DEAN FALK: And all of these are indications of higher cognitive activity. So we think it was a new species and a really interesting one.

NARRATOR: But Falk acknowledges that some scientists are leery of inferring an entire species from one vanished brain.

DEAN FALK: We need more fossils. And then of course D.N.A. evidence. But that can be hard to come by if weather conditions aren't conducive, and tropical kinds of habitats don't make for good preservation of D.N.A. But they're hunting, and I hope they find it.

NARRATOR: D.N.A. would settle whether the hobbit was a diseased modern human or a new species, but, so far, no D.N.A. has been recovered.

For anthropologist Shara Bailey, however, teeth might be enough to nail the hobbit's identity.

SHARA BAILEY (New York University): I thought it would be a very simple task. I thought it was just a matter of taking a look, and I'd be able to tell without a doubt. And it became very complicated.

NARRATOR: Shara had two sets of teeth to compare: those in the skull of the main skeleton called LB1 and the complete lower jaw of another hobbit, who lived thousands of years earlier. She focused on the premolars, teeth used for grasping.

SHARA BAILEY: Originally, when I saw LB1, I thought, "Well, this is just pathological." And then, when they showed me the second one, and it had the exact same premolar, I was really perplexed.

NARRATOR: The premolars were strikingly similar, which meant either that two individuals living thousands of years apart suffered from the same disease, or their teeth were normal for their species.

SHARA BAILEY: It just doesn't make any sense.

NARRATOR: Shara asked biologist Tim Bromage for help.

TIM BROMAGE (New York University College of Dentistry): The structure of bones and teeth tell a huge amount about the life history of an organism. And they can also settle disagreements about whether the tissue is normal or comes from someone with a pathological disturbance.

NARRATOR: Something about the teeth struck Bromage.

TIM BROMAGE: The teeth are nearly human in size, but the front to back dimension of every single tooth has been shortened to accommodate the much smaller jaw. There is no pathology that I am aware of that so completely and utterly transforms every bit of the skeleton and every single tooth in the mouth. There just isn't one.

NARRATOR: To Bromage, it seemed evident that evolution was at work, not disease.

And hobbit bones tell the same story. Matt Tocheri's passion is music and also the study of the hands and feet.

MATT TOCHERI (Smithsonian Institution): Over half of all the bones in our skeleton are in our hands and feet. And so they tell a big portion of the story of our evolutionary history.

NARRATOR: Tocheri's specialty is the small bones of the wrist, the carpals, which reveal the changes in primate evolution over millions of years.

MATT TOCHERI: You can imagine, after spending five years of my life looking at nothing but these wrist bones from humans, chimpanzees, guerrillas, orangutans, baboons–you name it–plus all the hominid fossils that we have, I mean, after a while, you really start keying in.

NARRATOR: The human wrist differs dramatically from the wrists of our early ancestors and apes.

MATT TOCHERI: It basically has a lot to do with a particular bone in the wrist, and that bone is the trapezoid. And that's the wrist bone that sits right underneath your index finger, right here. And it's lodged between several other wrist bones. And in African apes and other non-human primates, that bone is shaped kind of like a pyramid, a triangular shape, where the tip of the pyramid is facing out of the palm.

NARRATOR: In apes, the forward-facing trapezoid passes force up and down the hand, helpful for hanging from trees or cracking nuts but difficult for bringing the thumbs and fingers together with precision.

MATT TOCHERI: But in us, what's happened is the wrist has been redesigned so that we are now more efficient at passing loads across this way.

NARRATOR: And that makes it easier for humans to grasp objects firmly and use their hands for complex tasks.

MATT TOCHERI: This is a very big difference, compared with all our non-human primate relatives. So this was a great test to look at the wrist bones from Homo floresiensis and see, does it look like humans and Neanderthals or does it like earlier hominids and African apes?

NARRATOR: Measurements revealed that the bone was triangular and thus, clearly not human.

MATT TOCHERI: I was more surprised than anyone, when I looked at it and realized it's a dead ringer for what we see in earlier hominids and African apes.

NARRATOR: But the skeptics argued, once again, that disease could be at work.

ALAN THORNE: If you're malnourished or if there is a developmental problem–and we know that this person did have some problems–then you would expect the ankle bones and the wrist bones to be any shape of bizarre.

NARRATOR: But Tocheri disagrees.

MATT TOCHERI: Wrist bones develop very early on during embryological development. Basically, by the time you are a 10-week-old embryo, these distinctive shapes that I just described have already formed. So all the genes that express themselves that result in things like hormone disturbances, or they result in things like dwarfism, or they result in things like microcephaly, many of those genes don't begin expressing themselves until well after the first trimester of development.

NARRATOR: Jungers is also convinced.

BILL JUNGERS: I've measured skeletons of pygmies from Africa, from the Andaman Islands, throughout Southeast Asia, and there's not a single human being on Earth that has the wrist of an australopithecus or a chimpanzee. The evidence is now pretty persuasive that we are looking at a new species.

MATT TOCHERI: Science doesn't deal with maybes. It deals with evidence, and we have the evidence in front of us now. Part of it comes from the wrist, and Homo floresiensis, the hobbits, as far as we know right now, they're the real deal.

NARRATOR: Many leading archaeologists and anthropologists now agree that the hobbit can no longer be dismissed as a diseased modern human. But if so, what is it, and where did it come from?

Wrestling with their different theories, key protagonists in the hobbit debate were drawn to Liang Bua to view the riddle at first hand. Skeptics and believers mingle side by side in the now-famous cave. The hobbit poses a challenge for all of them. It threatens to overturn our understanding of where we come from and the type of ancestors that have shared the human family tree.

BERT ROBERTS: This one was a real media blizzard. I think it was because it was a small person, and the fact that they overlapped in time with us, and we thought we had the last 30,000 years clear to ourselves. Another human species? No, no, no. We replaced all of them; that's the natural order of things.

NARRATOR: But is it? Our understanding of human origins is surprisingly incomplete. Despite the discovery of hundreds of skulls, multiple hominin species, and thousands of bone fragments, large gaps remain in the fossil record.

HENRY GEE: Despite decades of patient work in pitiless places, we still know rather little about the evolution of humanity.

NARRATOR: As a senior editor of the science journal Nature, Henry Gee follows the leading research in anthropology.

HENRY GEE: The remains we have are very scarce and very meager. And that means that there were probably lots of different species that existed, that came into being, that lived for hundreds of thousands of years and then became extinct, and we know nothing about them. And all you need is just one to completely blow apart your well-entrenched, comfortable idea of the linear progress of evolution.

NARRATOR: Could the hobbit be that species? It certainly challenges key assumptions that the savannahs of Africa were the sole cradle of humankind and that evolving a bigger body and brain is what let us leave the cradle and spread around the world.

Could evolution have taken a different path than anyone imagined?

ALAN THORNE: There are some very big things at stake here. And it raises questions which would destroy, for some people, a huge amount of work.

MIKE MORWOOD: Some of our critics find this hard to swallow. It doesn't fit with their preconceived ideas about the onward, upward progress of human evolution. And Homo floresiensis has no business being here 12,000 years ago.

NARRATOR: To make sense of the surprise, scientists are trying to determine where the hobbit fits in our evolutionary tree.

CHRIS STRINGER: This is one of the most challenging aspects of the find. In arriving at this creature, what was the ancestor?

NARRATOR: To explain Homo floresiensis, we have to know what it evolved from. And given where it lived, one ancient species must be considered a prime candidate. Its official name is Homo erectus, but it has also been known as Java man, because that's where it first turned up–on the island of Java, near Flores.

At Leiden University in Holland, two specialists in Indonesian fossils have come to view the original Homo erectus skull. When this fossil was discovered, in the late 1800s, John De Vos and Robin Dennell know that it was as controversial as the hobbit is today.

ROBIN DENNELL (National Museum of Natural History, The Netherlands): The significance of erectus is that it's supposed to be the first kind of human ever to live outside of Africa. According to long-standing views, around about 1.8 million years ago, it left its African homeland and dispersed across Asia and eventually reached Java. That's why it is so significant.

NARRATOR: But could Homo erectus, tall and big-brained, really have evolved into a pint-sized version of itself?

John De Vos believes it could, because strange things happen to animals on islands.

JOHN DE VOS (National Museum of Natural History, The Netherlands): On the islands you see the phenomenon that large mammals become small and small mammals become large.

NARRATOR: And nowhere is the so-called island rule more evident than on Flores. Rats once grew as big as rabbits, lizards became Komodo dragons and pygmy Stegodon elephants, the size of cows, evolved from ancestors eight feet tall.

BERT ROBERTS: If you want to live somewhere that doesn't have many nutrients, it helps if you're small. You can still get a little bit smaller and survive, if there are no big predators around.

NARRATOR: Facing few predators and limited resources, species isolated on islands grow or shrink to survive.

The Dutch museum is full of such examples.

JOHN DE VOS: Here, I have the pygmy Stegodon from Timor.

ROBIN DENNELL: Wow isn't that small? Just shows what happens on islands, doesn't it?

NARRATOR: The same evolutionary pressures that produced pygmy elephants, turned Homo erectus, De Vos believes, into a hobbit.

JOHN DE VOS: All those characters of the hobbit you can explain in the island phenomena.

ROBIN DENNELL: So you are saying it's an island-endemic form.

JOHN DE VOS: Yes.

NARRATOR: But Dennell doubts Homo erectus evolved into a hobbit. The island effect, he argues, has never been known to shrink a human brain.

And CAT scans of the hobbit's bones lead Bill Jungers to the same conclusion. He too, sees no evidence of a shrunken Java man.

BILL JUNGERS: I'm less and less persuaded that this is some kind of dwarfed Homo erectus. I suspect that we are looking at an ancestry that even predates Homo erectus.

NARRATOR: The hobbit is forcing scientists to consider a strange possibility.

ROBIN DENNELL: The more interesting scenario is that the hobbit was already small when it arrived, and perhaps its own ancestry goes back to something at the very base of the evolution of our own genus.

NARRATOR: Something like Australopithecus. Approximately hobbit-sized in both body and brain, it is one of our most primitive, bipedal ancestors.

The most famous Australopithecus is Lucy, a skeleton found in Ethiopia. She's at least 3,000,000 years old. Other such remains have shown up across Africa, but never outside of it, until, perhaps, now.

But how does the hobbit measure up to Lucy? To find out, casts made of her bones were shipped to Jakarta. Bill Jungers compared the two skeletons. He first tried fitting the bone at the base of Lucy's spine to the hobbit's pelvis.

BILL JUNGERS: I was shocked. I am amazed by how similar Lucy is to LB1.

NARRATOR: Despite being separated by millions of years, pieces of the skeletons fit together easily.

BILL JUNGERS: The humerus is almost identical in length, the femur is almost identical in length; the pelvic morphology is now turning out to be very similar in size and shape.

NARRATOR: Could the hobbit be a descendant of an Australopithecus, like Lucy? To many scientists, the idea is heresy. They always assumed it took large brains and bodies to make the arduous journey out of Africa.

BERT ROBERTS: But the reality is that this is looking more and more like an Australopithecine escaped from Africa–no time recently, 2,000,000 years ago, maybe 3,000,000 years ago–and then got stranded out there on this tiny little island, leaving no remains anywhere else throughout Southern Asia, apart from this one cave that we just happened to dig in.

ROBIN DENNELL: And that might imply that there is, in fact, a hidden Asian lineage of hominins that is only recorded, so far, in Flores, at the very end of its trajectory.

NARRATOR: Dennell believes traces of this lineage may be found in the vast plains that once extended from Africa to Asia, a region he calls "Savannahstan." We know animals crossed it, so why not early humans?

ROBIN DENNELL: Those Asian grasslands are, in fact, far older and more extensive than those in Africa, and so one could advance the argument that maybe the Asian grasslands also played a major part in the early part of our own evolution.

NARRATOR: What Dennell is suggesting is that ancient hominins didn't just pass through Savannahstan, some might have evolved there.

CHRIS STRINGER: It implies that we are missing a huge amount of the story of human evolution in Asia, that creatures got out of Africa very early, without us knowing the record of their evolutionary history, and they then spread widely outside of Africa.

NARRATOR: If this scenario is true, wouldn't these earlier ancestors have left some sign of their existence?

BERT ROBERTS: Trying to find them is proving to be exceedingly difficult, but we need to find those remains, if we're to find out exactly how the hobbit got into its present state, how it evolved over time.

NARRATOR: But the crucial evidence Roberts is hoping for may have already been found. On the western fringe of Asia, at Dmanisi, in Georgia, a new discovery supports the idea of a hidden Asian lineage.

On the grounds of a medieval village, there's been a find to rival the one on Flores. Here archaeologists found a trove of surprising fossils, fossils which David Lordkipanidze believes also shatter past notions of the human exodus from Africa.

DAVID LORDKIPANIDZE (Georgian National Museum): This is a unique place, where we could learn lot of about human evolution. The chapters we can never imagine to learn.

NARRATOR: Over the past decade Lordkipanidze has discovered five unique skulls from what appears to be a colony of early hominins. And just like the hobbit, they are small, with small brains, too.

DAVID LORDKIPANIDZE: This is the original Dmanisi skull. It was a very big surprise when we found it. It's very small with a very teeny brain capacity. If we will compare it with modern humans, they are much more primitive. It has brain capacity 600 cubic centimeters, then modern humans have more than 1,500. So this skull is first human ancestor out of Africa. They are oldest human ancestors in whole Eurasia.

NARRATOR: The Dmanisi skulls are much older than the hobbit, each is at least 1.7 million years. Given this expanse of time, is it possible they belonged to an ancestral species which evolved into others, including the hobbit?

DAVID LORDKIPANIDZE: This skull belongs to the hominid who could be possible ancestor of the Homo erectus and Flores, too.

CHRIS STRINGER: It raises all kinds of questions about where the human line began. And it could be used to support the idea that humans originated outside of Africa, again a very challenging idea.

NARRATOR: But not out of the question, given how little we know about our past.

ROBIN DENNELL: You see, the fossil evidence we have from Asia for the first million years or so of our existence, would more or less cover this table and little more. If we go back to 2,000,000 years ago or beyond that, we have absolutely nothing from Africa's neighbor, which is Southwest Asia. So, who knows what was living outside Africa at...2,000,000 years ago?

NARRATOR: Dmanisi may be the evidence that makes sense of the hobbit. If nothing else, it proves that Asia was once a habitat for little hominins.

DAVID LORDKIPANIDZE: We could say that human evolution was not just simple straight highway. It was very complicated. It was very exciting story. And Flores and Dmanisi both are bringing new questions.

HENRY GEE: The finds at Dmanisi in Georgia are remarkable. And they just go to show everything that's true about paleoanthropology, which is you find the most unexpected things in the most unexpected places.

NARRATOR: Although questions about our origins seem endless, in Paris one of them may soon be answered. In honor of Morwood's find, the Museum of Mankind has commissioned sculptor Elisabeth Daynes to reconstruct the hobbit based on the latest forensic techniques.

We may not be the first modern humans to have seen what the hobbit looked like. For if Morwood is right, humans and hobbits shared this planet for thousands of years and may have met countless times, just as the folktales of Flores report.

And who's to say there are not other surprises awaiting us?

HENRY GEE: The world is full of undiscovered hominids, and I wouldn't be at all surprised if, one day, somebody sent a paper to Nature saying they found one alive, living somewhere in Sumatra or Vietnam or somewhere. I would be very, very excited, but I wouldn't be at all surprised.

The hobbit challenges our preconceptions in so many ways. We're still very much just at the beginning of the story. I think the best is yet to come.

NARRATOR: For nearly 80,000 years, the hobbits flourished on Flores.

BERT ROBERTS: They were tremendous survivors. You've got to admire their longevity. And it's still a moot point as to why they went extinct. I mean, what finally put the death knell on the hobbits? We still don't really know the answer to that question.

NARRATOR: Most likely a volcanic explosion wiped them out, leaving us Homo sapiens alone on the planet.

Back at Liang Bua, Mike Morwood and his Indonesian colleagues are planning new excavations. And they've identified other promising sites to explore.

MIKE MORWOOD: This will stand Southeast Asian archaeology on its head, and will yield other spectacular discoveries of a similar magnitude to Homo floresiensis. Of that I'm certain.

NARRATOR: And if more evidence is found establishing beyond doubt that the hobbit is a new species, what will it mean?

CHRIS STRINGER: If this is a deep and separate lineage, then it confirms the complexity of human evolution. And what's most fascinating here is that most of those early experiments vanished 2,000,000 years ago. And they evolved into other things or they went extinct. Here we've got something which may represent that very early stage of human evolution going its own separate evolutionary way, maybe for 2,000,000 years. So it's a quite incredible story. And it shows that nature, in a sense, was experimenting with how to be human.

NARRATOR: On NOVA's Alien from Earth Web site, compare the brains of a hobbit, a chimp and a modern human, explore a timeline of human evolution and more. Find it on PBS.org.

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