Tag: Hobbits (Homo floresiensis)

On My Fossil Wish List: Homo sulawesiensis

By Carl Zimmer | January 29, 2007 11:38 pm


Could 2007 see some new hobbits? I certainly hope so.

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Homo floresiensis: Two Years Out

By Carl Zimmer | October 9, 2006 1:21 am

new%20hobbit.jpgTwo years ago this month, I was taken aback by some explosive news. A team of Indonesian and Australian scientists reported that they had discovered fossils of what they claimed was a new species of hominid. It lived on the island of Flores in Indonesia, it stood three feet tall, and it had a brain about the size of a chimp’s. Making the report particularly remarkable was the fact that this hominid, which the scientists dubbed Homo floresiensis, lived as recently as 18,000 years ago. I wrote up a post on the paper, and took note of some strong skepticism from some quarters. And since then, I’ve found myself devoting a number of posts to the new papers from the discoverers of Homo floresiensis, and the emerging responses from the skeptics–so many that I gave them their own category. Recently there’s been so much stuff coming out pro and con that I have had to skip a couple opportunities to blog on Homo floresiensis–mainly because I’ve been frantically deep in the first draft of my current book on a very different topic: Escherichia coli. (I assume Homo floresiensis carried Escherichia coli in its gut, but the overlap stops there.)

Fortunately the first draft is now done, so I can let my mind drift back from the microbial world, to Homo floresiensis. And it just so happens that a big new paper has come out today which is a good topic on which to blog.

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Return of the Microcephalic Hobbit

By Carl Zimmer | August 21, 2006 7:45 am

new%20hobbit.jpgThe Sunday Times in the UK reported yesterday on an upcoming paper that claims that the ever-fascinating Homo floresiensis (a k a the Hobbit) is not a new species, as previously reported. Instead, it was a human with a genetic defect called microcephaly that gave it a small head.

This is a long-standing criticism, but only a couple papers based on it have been published since the Hobbit fossils were discovered almost two years ago. The article doesn’t have a lot of details. When the new paper comes out (in the Proceedings of the National Academy of Sciences) I guess we’ll get more.

For my previous hobbit tales, go here.

Update: 4/21 12:30 pm: PNAS was keeping the paper under embargo, but now with the Times story out, they’ve lifted it. So there’s a flood of information out now:

John Noble Wilford in the New York Times

Press release from Penn State

Still no paper posted yet at PNAS’s own web site, though…

Update, 8/22 9:50 am: John Hawks muses.


Hobbits: Happy, Healthy, Human?

By Carl Zimmer | June 21, 2006 9:24 pm

hobbit head-lo.jpgIt’s been twenty months now since scientists reported discovering fossils on the Indonesian island of Flores belonging to a three-foot-tall hominid with a brain the size of a chimp that lived recently as 12,000 years ago. Homo floresiensis, as this hominid was dubbed, has inspired two clashing interpretations. Its discoverers declared it a separate species descended from another branch of hominids. In others words, the most recent common ancestor we share with Homo floresiensis lived two or even three million years ago. Skeptics argued that the fossils belonged to human pygmies. The one fossil of a Homo floresiensis brain-case belonged to a female with a rare genetic defect. In brief: healthy hominid versus deformed human.

Now comes a third theory. In brief: healthy human.

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Small Girls with Sharp Rocks

By Carl Zimmer | June 9, 2006 10:13 am

hobbit head-lo.jpgWhen we speak of the Hobbit, let us not forget her tools.

Last year, scientists reported discovering fossils of a three-foot-tall hominid that they named Homo floresiensis, and which I can’t keep myself from calling the Hobbit. Its bones turned up in a cave on the Indonesian island of Flores, dating from 97,000 to 12,000 years ago. The scientists argued that the Hobbit represented an ancient lineage of hominids, perhaps descending from Homo erectus, a human-sized species that existed in Asia 1.8 million years ago, or perhaps belonging to even an older lineage, known as australopithecines. Critics argued that the Hobbit was probably a fellow Homo sapiens. They generally focused their attention on Homo floresiensis’s skull. Only one skull has yet been found, from an adult female. It’s an odd skull at that, one that would have housed a strangely shaped brain a third the size of a normal adult human brain. As I wrote last week, the critics suggest that the Hobbit might have had a genetic disorder called microcephaly, which leads to very small heads. (The full repository of my Hobbit obsessions can be found here.)

With all the attention currently being lavished the Hobbit’s head, it’s easy to forget all the other things that have come out of the same cave. Scientists have found various chunks from its jaws, arms, and other bones, which have lots of weird features. These features suggest a separate species, the Hobbit team argues, not a deformed human. There’s a continuity that you can trace from the oldest bones to the youngest, a span of over 80,000 years. The critics haven’t had much to say on that point, although it’s only fair to point out that their output so far has been a few short papers. Longer rebuttals are in the works.

And then there are the tools.

Tools were actually what got the paleoanthropologists excited about Flores in the first place. In 1994 they found tools dating back roughly 800,000 years at another site on the island. The scientists speculated that the tools were made by Homo erectus that had gotten from Java across a wide expanse of open water to Flores. Whether they traveled by boat or tsunami-driven tree was an open question. The discovery spurred an intense search of the island for fossils of the toolmakers. The scientists found the much younger Hobbits instead.

But along with the fossils, the scientists also found more tools. In the initial reports on Homo floresiensis last year, the scientists reported that the tools spanned the oldest to youngest deposits where fossils had been found. Bones of dwarf elephants also found in the same layers suggested that the Hobbits were using the tools to hunt–perhaps even attaching the stone blades to sticks to make spears. As for the older tools, the scientists only said the identity of their creators would have to remain a matter of speculation.

Skeptics from the start wondered whether the Hobbits had actually made the tools. Paleoanthropologists Marta MirazoĢn Lahr and Robert Foley wrote a commentary for Nature on the initial papers last year in which they pointed out that

elsewhere such implements are associated with H. sapiens, and their contrast with tools found anywhere with H. erectus is very striking. One could speculate that modern humans, who were dispersing across southern Asia between 100,000 and 50,000 years ago, may have made the tools, and come across these creatures.

Others argued that a hominid with such a tiny brain could not have possible made or used such sophisticated tools.

hobbit%20tool.jpgIn tomorrow’s issue of Nature, the Hobbit team takes on the skeptics yet again. They’ve analyzed all the old tools from Flores–the original 1994 cache and another trove that turned up not far away in 2004. (This picture shows the front, back, and side view of one of the 2004 finds.) New dating shows that some of these 507 tools date back at least 840,000 years ago. The scientists compared them to the 3626 younger tools found with the Hobbit bones.

The scientists found that the two sets of tools share many things in common. They were typically made from volcanic rocks found along rivers. The tool makers knocked off bits from these rocks in a similar fashion, creating a front and back face and sharpening the edges. In some cases they seem to have used anvils–setting their tools-in-the-making on other rocks before banging on them. Both sets of tools include distinctive kinds of tools, such as “perforators” with a long spike extending from a rounded base.

The simplest explanation for these similarities, the authors conclude, “is the stone artefacts from Mata Menge and Lui Bua [the old and new tool sites] represent a continuous technology made by the same hominin lineage.”

They argue that the notion that the new tools were produced by humans, as floated by Lahr and Foley, doesn’t fit the evidence. They point out that the oldest indisputable fossils of Homo sapiens on Flores are 10,500 year old. Along with those bones, tools have been found that don’t fit into the continuum from Mata Menge to Lui Bua. They include grinding stones and other tools never seen in older sites on Flores. And along with tools, humans arriving on Flores also made beads and formally buried their dead and left lots of other evidence of a very different mental make-up from Homo floresiensis. It makes more sense that humans showed up on Flores only after the Hobbits became extinct (perhaps during a volcanic eruption) and brought lots of new tools with them. As for the claim that small-brained Hobbits couldn’t possibly have made the tools found with them, the scientists argue that this is an assumption cloaked as a conclusion.

Inevitably, this study raises more questions than it can answer at the moment. I for one found myself thinking a lot about the size of the tools. Hobbits were small, and they had small hands. If Hobbits descend from Homo erectus, then they must have shrunk from a height of five to six feet to just three. On the other hand, if they descend from australopithecines or some other small lineage, then they might have arrived on the island already small. Would the size of the proto-Hobbits have been reflected in the size of their tools?

veronica%20hobbit.jpgTo visualize this matter, consider my Hobbit-sized daughter Veronica. She’s holding a rock that is about the size of an old Flores tool. I didn’t try to make a perforator for her, since I’m a lot clumsier than your typical Pleistocene hominid. Even if I had managed to make one, I doubt my wife Grace would have looked kindly on giving little girls sharp rocks. And it must be clearly stated that Homo floresiensis almost certainly never wore a Cinderella outfit. Snow White maybe, but never Cinderella.

The rock fits pretty well in her hand, I must say. Did this mean the old hominids of Flores were Veronica-sized? I sent an email to Adam Brumm of Australia National University, the lead author of the paper who did much of the analysis for his Ph.D. “The stone tools from Mata Menge and Liang Bua are basically the same size – all quite small,” he replied. It’s possible that the old hominids were already small, or that they were big but kept their tool kits light.

Brumm pointed out that Homo floresiensis may have carried rocks some distance from rivers before turning them into tools. Those rocks would have been much larger, but that doesn’t necessarily mean that the early inhabitants of Flores must have been big. After all, chimpanzees are short but extremely strong.

“There may well have been limitations on the maximum size of the stone artefacts H. flo could conveniently manipulate given their small hands but you would have to find a way to test this,” Brumm wrote. “H. flo might not be much bigger than your daughter, but if they were twice as strong or more than a full grown man imagine her flinging a sledge-hammer around the room and the constraints on tool handling become less apparent.”

When Veronica starts throwing Legos around, I’ll just try to remember that it could be worse. I could be dodging sledgehammers.

CATEGORIZED UNDER: Hobbits (Homo floresiensis)

Jakob the Hobbit?

By Carl Zimmer | May 18, 2006 2:01 pm

hobbit head-lo.jpgIt’s been a little over a year and a half now since scientists announced the disocvery of the most controversial fossil in the field of human origins: Homo floresiensis a k a the Hobbit. Scientists found bones of a dimunitive hominid on the Indonesian island of Flores, and estimated that it lived there as recently as 12,000 years ago. It stood about as high as a normal three year old human child and had a brain the size of a chimpanzee’s. But its bones were also found with stone tools. The scientists declared the bones were not human. Instead, they belonged to a species of their own–one that branched off from much older hominids. Later, the scientists offered brain scans and more bones to bolster their case.

I’ve been chronicling the adventures of Homo floresiensis, trying to keep an eye out for new developments. My hobbit posts can be found here. In recent months the scientific reports have tapered off. That may be in part because of the ugly spat between rival paleoanthropologists over access to the bones and the site where they were found. Critics have been putting together attacks against the creation of a new species (most think the bones are from human pygmies, perhaps with birth defects). But those critical papers are slow in coming out.

Today we have the latest development in the hobbit wars, a critical paper from a team of American and British scientists and a response from the original team of scientists. They appear in the journal Science. I wish I could report some big surprising news, but these papers seem to be circling around two of the same questions that scientists have been asking for some time.

The new critical report comes from Robert Martin of the Field Museum in Chicago and his colleagues. The fact that Martin is not happy with the initial reports on Homo floresiensis is no secret. As I wrote last October, he was already working on his response back then, and Kate Wong at Scientific American offered some details in March. It’s still illuminating to look at his detailed comments in print.

There are two points to Martin’s complaint.

1. They picked the wrong human brain for their comparison. From the start, some critics argued that the hobbit was just a human with a case of microcephaly, a birth defect that produces a dramatically shrunken brain. Dean Falk of Florida State University led the effort to scan the brain case of Homo floresiensis, and for a point of comparison, she chose cast of a brain case of a microcephalic in the collection of the American Museum of Natural History. She concluded that the hobbit brain case looked less like that of a human microcephalic and more like the brain of Homo erectus, a six-foot tall hominid that appeared in Indonesia perhaps 1.8 million years ago.

Martin and his colleagues did a little detective work and discovered that the skull belonged to one Jakob Moegele, a German boy who died at age ten. Studying the original skull, they argued that it was a poor choice for a comparison. Moegele was a child, while the Hobbit was an adult. What’s more, his cranial capacity (272 cc) was very small for a microcephalic. Martin and his colleagues offered some sketches of a skull and two preserved brains of microcephalics that they claim are more similar to the Hobbit.

2. You can’t get a Hobbit by shrinking down Homo erectus. Lots of mammals have evolved from bigger to smaller–even elephants can become miniature. And by comparing related species of different sizes, scientists have gotten a rough idea of how their bodies change as they shrink. It turns out that bodies shrink faster than brains. As a result, small mammals have bigger brains relative to their bodies than big animals.

Martin and his colleagues used various formulas for brain and body dwarfing to predict what would happen if Homo erectus shrank down to Hobbit size. They found that its brain would have been far bigger than the actual size of Homo floresiensis’s fossil suggests. In fact, in order to get down to the Hobbit’s tiny brain, Homo erectus’s body would have to shrink down to a gram!

“We conclude,” Martin and his colleagues write, “that LB1 [the Hobbit fossil skull] was not an insular dwarf and may have been a microcephalic modern human.”

In the same issue of Science, Falk and her colleagues responded to both points.

1. Our scans beat your sketches. Falk and company point out a lot of shortcoming in the sketches Martin offers. The brain drawings lack crucial details about their structure, and the skull drawings are not accompanied by any information about what they look like inside. “Without this evidence,” Falk and company write, “the assertions of Martin et al remain unsubstantiated and difficult to address in further detail.”

2. Who said anything about a dwarf Homo erectus? Falk and her colleagues point out that while the brain had a Homo erectus-structure, they wrote that it “is too small to be attributed to normal dwarfing on H. erectus and further showed that its relative brain size is consistent with those of apes/australopithecines.” Australopithecines were an early wave of hominid species that lived from about 4.5 million to 2.5 million years ago. They could walk upright, but they were short and had brains not much bigger than a chimpanzee’s. And there’s no clear evidence from the fossil record that they ever left Africa. Homo erectus is among the earliest hominids to be found out of Africa.

That’s it. Frankly, I had a feeling of deja vu reading this material. Last October, I wrote about another attack in Science. Those critics had microcephalic brains of their own to show, but Falk argued that they also failed to analyze the brains in a consistent way. I wondered then, and I wonder now, why the editors of Science don’t make sure that everyone agrees on the ground rules for comparing these brains before they publish? Otherwise both sides just squabble about methods and presentation, rather than about meatier matters.

The problem may be that in both cases Science has relegated this exchange to the “Technical Comment” section, where reports are much shorter than normal papers. The descriptions of methods used in the research are often scant, and the comments also tend to include cryptic interpretations that cry out for more explanation. Falk and her colleagues say that the Hobbit’s brain is consistent with apes or australopithecines, not Homo erectus. Now, I’d imagine that this might imply that the Hobbit descends not from Homo erectus, but from some Australopithecine that came out of Africa. That would be huge news if true. Yet the scientists just leave us hanging with a statement that is so cryptic as to be nearly useless.

I hope that the debate doesn’t keep circling this way until someone finds a new fossil on Flores or some other Indonesian island. We hobbit junkies need a better fix.

CATEGORIZED UNDER: Hobbits (Homo floresiensis)

Kate Wong on the Hobbit Trail

By Carl Zimmer | March 22, 2006 8:56 pm

Kate Wong, Scientific American’s excellent paleo reporter has a two-parter on the latest dish on Homo floresiensis a k a the Hobbit. No cymbal crashes, I’m afraid, but interesting nonetheless.


Do Not Arm-Wrestle With Hobbits

By Carl Zimmer | February 8, 2006 11:02 pm

hobbit head-lo.jpgPeter Brown, one of the discoverers of Homo floresiensis a k a the Hobbit (previous posts here), had a few interesting remarks in an article in today’s Oregon Daily Emerald:

Though the hobbit people were very small — the adult stood as tall as a 3-year-old human child and had a brain the size of a newborn human baby — they had incredible strength, Brown said.

“Chimpanzees have an arm strength four times that of a human; the hobbits were similarly as strong, we think,” Brown said. “You wouldn’t want to arm wrestle one, that’s for sure. It would probably snap your arm off.”

Since the discovery of the first female, a mostly complete skeleton, Brown’s team has found parts of six or seven others that are mostly the same as the first one, Brown said.

“We have found about half of the remains of a 3-year-old that is half-a-meter tall,” he said. “You could put its leg across an American $1 bill.”


The Hobbit’s Brain

By Carl Zimmer | March 3, 2005 2:00 pm

hobbit brain.gifAt 1 p.m. today I listened by phone to a press conference in Washington where scientists presented the first good look inside a Hobbit’s head. The view is fascinating. While it may help clear up some mysteries, it seems to throw others wide open.

Last October, a team of Australian scientists declared that they had found a new species of hominid that lived as recently as 12,000 years ago. It was short–maybe three and a half feet tall–and had a brain they estimated to be about the size of a chimp’s. Its bones were found along with stone tools, suggesting that it made good use of its scant grey matter. The fossils of this remarkable hominid were discovered in a cave on the island of Flores, which gave the hominid its name: Homo floresiensis.

As soon as the news broke of the discovery, some researchers expressed grave doubts. They suggested that H. floresiensis was actually just a group of human pygmies. The fossils discovered on Flores include only a single skull, and these skeptics suggested that its small size might be the result of a genetic defect known as microcephaly. If H. floresiensis’s discoverers had found another skull instead, it would likely have displayed the sort of shape you’d find on a living pygmy human.

This scientific debate quickly got eclipsed by an ugly tussle over the bones. A skeptical grand old man of Indonesian paleoanthropology, Teuku Jacob, wound up with the fossils for four months, during which time he arranged for other scientists to examine it and for some bone to be sent to Germany for DNA testing. Now he’s surrendered the fossils, and it looks as if we may be able to enjoy some actual scientific discoveries about these bones, rather than a yelling match. (Those interested in a more detailed chronicle and a fair number of links to more information may want to check out my previous Hobbit posts.)

Before the Hobbit bones wound up in Jacob’s safe, its discoverers had a chance to look inside its head. They enlisted the help of Dean Falk, a Florida State University paleoanthropologist who has spent years studying the interiors of hominid skulls to find clues to what their brains were like. While brains rot quickly, they leave behind marks where some of their folds and blood vessels were. And since the skull forms such a tight seal around the brain, it ends up with roughly the same shape. To get a good look at these details, Falk has helped pioneer the use of CT-scans to visualize the insides of hominid skulls.

The Hobbit skull was scanned in Jakarta at a 1-mm resolution, and the data was then processed at Washington University’s medical school. Falk and her colleagues then analyzed the interior of the skull to calculate the size and shape of the brain, and then produced a three-dimension model of it.

Falk and her colleagues made a careful study of the size and shape of the Hobbit brain, and then they created three-dimensional models of the brains of other hominids. They compared it to the brains of average female humans, a female pygmy, and a microcephalic girl. (They chose females because the Hobbit skull is believed to belong to a female.) The scientists also looked at endocasts of fossil hominids. As I mentioned in my earlier posts, the discoverers of H. floresiensis suggested that it might have evolved from Homo erectus, a tall, large-brained hominid that is believed to have left Africa about 2 million years ago and spread across Asia. Falk’s team looked not only at five Homo erectus skulls, but skulls of earlier hominids from Africa, such as Australopithecus africanus and Paranthropus aethiopicus.

The results are being published today on Science Express, the online arm of Science magazine (a printed version will come out in a future issue). The most straightforward results are the ones that address the skeptical suggestions about a small-brained human. The Hobbit brain doesn’t look anything like the brain of a microcephalic. Microcephalics have smooth brains, for example; the Hobbit has a normal convoluted surface. Microcephalic brains have a pointed top and a sloping forehead; the Hobbit brain is rounded on top and unsloped in front.

Nor does the Hobbit brain seem to belong to Homo sapiens. It is small (417 cc, which is less than a third the size of an average human brain), and lacks the distinctive shape of human brain. It is wider from ear to ear than it measures from the front to the back of the head, for example. The brains of human pygmies are indistinguishable from those of taller humans, both in size and shape.

Of all the brains that Falk and co. compared to Homo floresiensis, Homo erectus came the closest–in particular, Homo erectus skulls from Java and China. They are also unusually wide, for example. But the Hobbit brain also has some strange features that set it off from Homo erectus. In some ways it is relatively primitive. For example, at the back of the Hobbit brain there is a relatively small occipital lobe. On the other hand, Falk and her colleagues noticed some traits in Hobbit brain that are more human-like. It has more convolutions at the front, for example, than Homo erectus. The temporal lobe, where hearing, memory, and emotions are handled, is enlarged, as well as the parietal association cortex, where some sensory information is handled. Perhaps most intriguingly, a region of the frontal lobes known as Brodmann’s area 10 seems to be very large in the Hobbit. It is also large in living humans, and is known to be important in planning and other complex kinds of thought.

Now, a study of single skull cannot be the last word about an entire population of hominids. But it strengthen some possible explanations for Homo floresiensis, and weaken others.

1. A few ordinary pygmies and a microcephalic: It’s hard to imagine how its advocates will be able to continue promoting it. I can imagine a skeptic saying, "Well, this person suffered from an unusual form of microcephaly that the scientists didn’t look at." But that would be a desperate reach.

2. An extraordinary group of Homo sapiens. Imagine that humans settled on Flores and then underwent a dramatic evolution that shrank their bodies and altered their brain structure. This explanation might account for the human-like features of the Hobbit brain.

But the time range of Hobbit fossils pretty much rules this one out. Modern populations of tall, big-brained humans are believed to have arrived in Southeast Asia about 50,000 years ago, and the oldest Hobbit bones are 95,000 years old. What’s more, tools on the island suggest that hominids have been on Flores for 800,000 years.

3. Descendants of Indonesian Homo erectus. It is less of a stretch to envision a population of Homo erectus evolving into the Hobbits. After all, its brain has the strongest overall resemblance to that of Homo floresiensis. And Homo erectus have been in southeast Asia for at least 1.8 million years. Perhaps a few Homo erectus individuals were swept onto Flores hundreds of thousands of years ago and gradually evolved smaller brains.

But this scenario is odd in its own way. It would require certain parts of the Homo floresiensis brain to have enlarged (relatively speaking), even as its overall brain size was shrinking drastically. And these enlarged regions allow us humans to do some of our most abstract thinking.

4. Something completely different. Before I explain what this might be, I have to explain a major problem with explanation 3.

Scientists have found a strong relationship between a person’s body weight and the percentage of their total weight made up by their brain. For a grown man of normal weight, the brain may make up just two percent of his weight. But a pygmy woman’s brain may be 3% of her body weight. These different percentages are the result of how the human brain and body grow. The brain grows rapidly during childhood and reaches nearly adult size around age ten. The body, on the other hand, grows more slowly and for many more years. Pygmies are smaller than average humans because their bodies stop growing earlier, but not before their brains have reached adult size. This relationship between brain and body follows a steady curve. It is so steady that you can predict what happens to the ratio of brain to body weight as humans evolve to smaller or bigger sizes.

Scientists have also drawn a similar curve for chimpanzees and other apes, but it’s noticeably different. That’s because their brain growth slows down dramatically after the first couple years, while their bodies can continue to grow to large size. For any given weight, a human’s brain is a higher percentage of his or her body weight than an ape’s brain.

It’s safe to assume that Homo erectus had its own curve. Drawing the curve isn’t easy, because there are precious few skeletons of Homo erectus that include both a brain case and enough of a skeleton to estimate their body mass. Actually, there’s just one, a 1.5 million year old skeleton from Kenya. Its brain and body size suggest that Homo erectus had a curve midway between apes and Homo sapiens. That’s a nicely unsurprising result, because adult Homo erectus stood about as tall as living humans but only had a brain about 900 cc. (Ours are 1350.)

Now come the Hobbits. Because the scientists have both the skull and some parts of the skeleton, they can estimate both its body weight–about 50 pounds–and the percentage of its body weight made up of brain: 1.7% They plotted this value on their graph and found that it did not fall on the human curve, nor on the Homo erectus curve. Instead, it fell on the ape curve.

What this means is that if you scaled down Homo sapiens to the size of the Hobbit, its brain would be much bigger than the Hobbit’s brain. And it also means that if you scaled down Homo erectus, it would also have a much larger brain than a Hobbit.

This suggests that the Hobbits actually descend from some other hominid, one with an even smaller brain than Homo erectus. How could this have happened, given that Homo erectus and Homo sapiens are the only hominids known from southeast Asia? Perhaps the Hobbits represent a major branch of hominid evolution that’s been hidden from view till now.

About six million years ago, the first hominids branched off from other apes in Africa, and until about 2.5 million years ago they had brains that weren’t much bigger than a chimpanzee’s. One branch appears to have evolved big brain and tall bodies, and paleoanthropologists believe that this branch gave rise to Homo erectus, Homo sapiens, Neanderthals, and perhaps a few other species. Paleoanthropologists generally believed that these big-brained hominids were the only ones to leave Africa. Homo erectus moved out first, followed by successive waves of Homo, until our own species expanded out of Africa about 50,000 years ago.

But in 2002 scientists found a baffling hominid skull in the former Soviet republic of Georgia. It was 1.75 million years old, it had some resemblance to Homo erectus, but it had an amazingly small brain, measuring only 600 cc. Larger Homo erectus-like fossils have also been found at the same site, dating back to the same age, and scientists have been arguing whether they belong to the same species or to different ones. Some scientists have suggested that the tiny Georgian hominid represented a second migration out of Africa. These migrants were not Homo erectus, but perhaps belonged to an older lineage of hominids. That lineage might have included one or more of the small-brained hominids that are the oldest known species to have used stone tools (Homo habilis, or Australopithecus garhi). Michael Morwood, one of the Hobbit’s discoverers who was at the press conference this afternoon, mentioned that Homo floresiensis has some Australopithecus-like traits in the lower part of its skeleton.

So here is a fascinating scenario to consider: a small-brained African hominid species expands out of Africa by 2 million years ago, bringing with it stone tools. It spreads thousands of miles across Asia, reaching Indonesia and then getting swept to Flores. It may not have undergone any significant dwarfing, since they were already small. This would change the way we think about all hominids. Being big-brained and big-bodied could no longer be considered essential requirements for spreading out of Africa. And one would have to wonder why early lineages of hominids became extinct in Africa when one branch managed to get to Flores.

So explanations 3 and 4 seem to come out strongest at the moment. Either one would mean that the Hobbit represents an amazing experiment in hominid brain evolution. They suggest that some human-like features emerged in hominids that were separated from us by two or maybe three million years of evolution. Yet their brains were mosaics, sharing features with us and with other hominids, and also had features of their own. These strange brains, Dr. Morwood argues, allowed Hobbits to do things some pretty elaborate things, such as butcher dwarf elephants or make fires. It would be wonderful to know how these strange brains were wired together, but we have to be content with their shadows. But even shadows can sometimes reveal a lot.


Return of the Prodigal Bones

By Carl Zimmer | February 24, 2005 10:26 am

floresiensis.gifThe Sydney Morning Herald reports today that the bones of Homo floresiensis, aka the Hobbits, have at last been returned to the team that originally discovered them.

The team, made up of Indonesian and Australian scientists, discovered the bones on the Indonesian island of Flores. Last October they declared that they had found a new species of diminutive, small-brained hominid that existed just 12,000 years ago. Then, in November, the bones wound up in the hands (or, rather, the locked safe) of the Indonesian paleoanthropologist Teuku Jacob. Jacob claims that a member of the Hobbit team asked him to look at the bones. Members of the team see things a bit differently: they accuse him of poaching. In response, Jacob has called them a bunch of would-be conquistadors. (I have some more background in my previous Hobbit posts.) Jacob promised to return the fossils by the end of 2004, but it is only now, two months later, that he’s made good.

But I’ll bet that we’ll be hearing again about this conflict before long.

Jacob has scoffed at the notion that the Hobbits are a separate species, saying instead that they were pygmy humans. He thinks the team that discovered the bones was fooled by the skull they unearthed. Its seemingly primitive condition, he claims, is the result of a birth defect called microcephaly.

This interpretation would, I imagine, please the minority of paleoanthropologists who are unhappy with the current consensus about modern human origins. Most researchers agree that all living humans descend from a small group of Africans who lived less than 200,000 years ago. Other hominids–Neanderthals, Homo erectus (and possibly Homo floresiensis)–became extinct. They may have mated with members of our own species when Homo sapiens came out of Africa about 50,000 years ago, but they’ve left behind little or now DNA in living humans.

But some researchers have stuck to an older hypothesis, that living humans have multi-regional roots that include Neanderthal and Homo erectus ancestors. In fact, they see no need to split up hominids of the past one million years into separate species.

It was thus not a complete surprise to learn last week that Teuku Jacob had arranged for two multiregionalists, Alan Thorne and Maciej Henneberg to examine the Homo floresiensis bones. Publicity may have been one motivation–a 60 Minutes crew was apparently filming the proceedings–but something very significant happened along the way. Two grams of the fossil material was extracted and sent to Germany to look for DNA.

As I’ve mentioned before, finding Hobbit DNA is the best way to test the hypothesis that these fossils belong to another species. If the Australians are right, its DNA should be only remotely similar to the DNA of all living humans. If Jacob is right, the DNA should resemble the DNA of living Southeast Asians more than other humans.

But any results that come from the DNA Jacob and company have extracted will probably be viewed with a lot of skepticism. It is very easy for fossils to become contaminated with the DNA of living humans once they are unearthed, and it very difficult to distinguish between contamination and any ancient DNA the fossils might contain. Jacob didn’t help matters when he "borrowed" the bones; apparently they were simply stuffed into a leather bag and brought to him. And his new colleague, Alan Thorne, has already drawn some intense criticism for not being careful enough about DNA contamination when he claimed to have found ancient genetic material from the fossils of early Australians.

For the time being the Australian-Indonesian team may not be able to help matters much. Reports indicate the they hadn’t extracted DNA from the fossils before the fossils were extracted from them. Still, the discovery has focused the world’s attention on the caves of Flores and nearby islands, which may translate into many hours of digging, which may in turn translate into a lot of new fossils in years to come. Here’s hoping that they aren’t yanked around so pointlessly.


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The Loom

A blog about life, past and future. Written by DISCOVER contributing editor and columnist Carl Zimmer.

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