The Loom

Hobbits again

hobbit head-lo.jpgFinally: more bones.

Last October the world marveled at the announcement of the discovery of a new species of hominid, Homo floresiensis, in a cave called Liang Bua on the Indonesian island of Flores. One conclusion was more shocking than the next. First, this hominid stood only three feet high, earning it the nickname The Hobbit. Second, it lived as recently as 18,000 years ago, which was some 30,000 years after our own species had already been in southeast Asia for 30,000 years or more. The scientists argued that Homo floresiensis was a separate species that might have descended from Homo erectus of East Asia–which would mean that the last common ancestor of the Hobbits and us lived perhaps two million years ago.

Homo erectus fossils have been found on Flores, dating back 800,000 years. The oldest H. floresiensis bones dated back 90,000 years. The researchers suggested that during the intervening period Homo erectus on the island might have dwindled from about six feet tall to three. And despite the Hobbit’s distant relation to our own species, not to mention its small brain (a third the size of a human’s, and about the same as a chimp’s), the scientists argued that it was a clever hominid. They pointed to the stone tools in the cave and the evidence they had found of fires. Just writing about this stuff nearly a year later makes me shake my head in shock.

As I have detailed in a series of posts here, things soon went from controversial to ugly. Several scientists went on the record with skeptical reactions. They pointed out that the bones came mostly from a single individual. They proposed that this individual was a pygmy (like the ones that live today on Flores), or was born with a congenitally small head, or both. One source of friction in the debate was the fact that some researchers see in the fossil record of hominids a lot of diversity while others see little. The fossils then wound up in the possession of a rival scientist who made casts of them, apparently damaging them in the process.

For the most part, Hobbit junkies like myself have had to content ourselves with reading gossipy articles in newspapers. The Hobbit’s discoverers published a brain scan of the fossil skull in April, but otherwise nothing appeared in scientific journals either from the discoverers or their critics. Until now.

In this week’s issue of Nature, the scientists describe bones from nine individuals from the Liang Bua cave. Some of the bones–parts of the right arm and jaw–belong to an individual. Other leg bones, shoulder bones, and various bits of fingers and toes come from other levels in the cave. They were laid down in the cave over thousands of years, the youngest being just 12,000 years old–around the time when our ancestors were inventing agriculture.

The key conclusion of the paper is that these fossils look a lot like the original Hobbit bones reported last year. The new jaw, for example, has the same peculiar roots on its teeth as the old one, and both also lack a chin. If the original Hobbit was just a pathological human, the authors argue, then all of these new individuals would have to be pathological too. And the fact that these fossils span 80,000 years makes it even harder to hold the pathology argument. According to Harvard’s Daniel Lieberman this pattern refutes the aberrant dwarf argument, which now "strains credulity," as he writes in an accompany commentary.

This is not the final chapter, by any means. Robert Martin of the Field Museum in Chicago has confirmed that he is putting together a paper that will dispute the claim that the Hobbit is something other than human, and others may well be up to the same. "Regardless of one’s stand on this issue," Dr. Martin wrote to me in an email, "it is about time that the message got out that there are serious grounds for doubt about current interpretation of the Flores remains."

This a vital part of the scientific process, but the high stakes in paleoanthropology always slow it down. And the bitterness caused by the tussle over Homo floresiensis’s fossils will probably make it even harder for these precious few fossils to be shared. Still, I’m curious to see how Martin and others expand their attack from the original individual to the expanded collection of Hobbits. (I’ll update this post when I come across any interesting responses from skeptics.)

If the Hobbits hold up under this scrutiny, there are still a lot of deep questions that will have to be answered. Were Homo erectus really their ancestors, for example? Tim White, a prominent paleoanthropologist at Berkeley, has suggested that they might be descended from our own species, having undergone a radical evolutionary change into a separate species of small-brained dwarves in just tens of thousands of years. The peculiar traits of Homo floresiensis such as its teeth might make that unlikely. The Nature author meanwhile offer some evidence that might suggest they belong to an even older branch of hominid evolution that Homo erectus. Earlier hominids, dating back before Homo erectus moved out of Africa, had the same overal body proportions as Homo floresiensis, as well as a small brain. Lieberman’s skeptical on this possibility, because there are so many traits that Homo erectus and Homo floresiensis share. Still, the exodus of hominids from Africa 2 million years ago still poses a lot of puzzles; maybe different pioneers leaving Africa around the same time gave rise to the two different species. And what about all the other islands of Indonesia? Are more little bones waiting to be found on them as well?

Unfortunately, on Flores at least, these questions may be left hanging. The dispute has led to the absurd situation that the team who found the Hobbits can’t get a permit to go back to Liang Bua. You have to wonder just how wise we are as a species.

More details here.

Update: 2:30 pm Greetings, visitors from the National Review. I’m not sure how the Hobbit fits in with The Corner’s political discussions, but I’m happy you’re here.

Update Friday 10/14: See my latest: a human with a Hobbit brain?

Comments

  1. #1 Vern
    October 11, 2005

    That picture is kind of freaking me out.

  2. #2 Peter Henderson
    October 11, 2005

    The BBC covered this recently on Horizon.Go to
    http://www.bbc.co.uk/horizon.Some of the scientists seemed to be suggesting that the hobbit was nothing more than a diseased modern human. It was an interesting programme with some of the arguments reminiscent of creationist rhetoric eg: neandertals were modern humans with rickets etc.

  3. #3 Brian S.
    October 11, 2005

    There were some reports a while back saying H. floriensis showed more sophisticated tool use than that ever found with H. erectus, despite having one-third the brain size. That’s always been a problem for me in accepting H.f. as a descendant of H.e.. Has there been a response to that issue?

  4. #4 francis till
    October 11, 2005

    Can you tell us more about the developments on the permit? We’d like to shine a little light on that bit of darkness but, alas, the Nature story is cost-firewalled. I’ve emailed Mike Morwood, but only just now, and wanted to put up a story online now, rather than wait for his eventual reply.

  5. #5 Doug
    October 12, 2005

    Brian, re the tool use, my understanding is that while tools were found at the site there’s no evidence linking them to the HF fossils. Those islands have been inhabited by Homo Sapiens for tens of thousands of years so you’d expect to find tools.

  6. #6 M Lees
    October 12, 2005

    I think that several issues may be being confused here.

    That there was a population of small (‘pygmy’) humans on Flores is I think not controversial. The remains of a number of them were found together (albeit in a very poor state of preservation), and now further specimens have been found.

    The controversial bit was the claim that the brain capacity of the one skull found was typical for the population. i.e. that Homo floriensis is a small brained member of the genus Homo derived from a larger brained form (either Homo erectus or Homo sapiens). Since only one skull was found, the evidence from the other remains is irrelevant to this argument.

    The new jaw bone confirms that a few of the features of the skull (the lack of a distinct chin and the unusual roots of the teeth) were probably characteristics of the population, but it does not confirm at all that any individuals other than the one whose skull was found had the reduced brain capacity. It is quite possible that the individual was an abnormal specimen of a distinctive pygmy population.

    While the issue must be decided on the evidence, he credentials of many of those who assert that the individual was a ‘microcephaliac’ or similar are such that they cannot be ignored. I also note that the tone of those defending the ‘small brained hominid’ position suggests that their objectivity is seriously compromised. Part of the problem here is that too many people want to believe in Homo floriensis as a small brained human (in the broad sense)derivative.

    At the moment I feel that the balance of evidence is in favour of the existence of a distinctive pygmy Homo sapiens population, with the single known skull being of an aberrant individual. On this basis Homo floriensis is probably an invalid junior synonym of Homo sapiens (one of many!). We must await more evidence to find out the answers.

  7. #7 Carl Zimmer
    October 12, 2005

    Modern humans did not leave bones in the cave until after 12,000 years ago. So as far as the fossil record at Liang Bua goes, the tools are associated only with Homo floresiensis.

  8. #8 Jason Malloy
    October 12, 2005

    In my opinion, the interpretation that is the most parsimonious and consistent with the available evidence is that Homo floresiensis is a pygmy relative of Homo erectus that lived contemporaneously with modern man and used tools made by modern man.

    I also note that the tone of those defending the ‘small brained hominid’ position suggests that their objectivity is seriously compromised.

    I wish I knew of a forum where this kind of thing was debated so passionately! Seriously though, I was given a completely different impression by the behavior of Teuku Jacob and his jeremiads against "latter-day conquistadors".

    "The new jaw bone confirms that a few of the features of the skull (the lack of a distinct chin and the unusual roots of the teeth) were probably characteristics of the population, but it does not confirm at all that any individuals other than the one whose skull was found had the reduced brain capacity."

    I disagree. The distinctive hominid characteristics of the rest of the skull anatomy give us good reason to think that the tiny hominid braincase is not aberrational. Also the CT evaluation by Dean Falk provides pretty convincing evidence away from (known/plausible) pathology and toward hominid brain structure as well as size.

    So that is six mutually reinforcing data points against the pathological human interpretation:

    1) Skeletal anatomy: Hominid. Not human. Not pathological.

    2) Skull anatomy: Hominid. Not human. Not pathological.

    3) Brain size: Hominid. Not human. Not pathological.

    4) Brain structure: Hominid. Not human. Not pathological.

    5) Multiple skeletons (including another jaw): Hominid (evidence against pathology).

    6) Furthermore, just by simple statistical reasoning, we know that non-pathological organisms of a species are going to greatly out-number those with extreme deformations, meaning that fossils of the former are much more likely to be found. For this reason, and given the small number of fossils samples of any species that are likely to be preserved, I think fossil explanations that rely on claims of extreme and unique pathology have a much larger burden of proof, making this interpretation of H. floresiensis even less likely. Why should we begin with inherently less likely assumptions?

    "Modern humans did not leave bones in the cave until after 12,000 years ago. So as far as the fossil record at Liang Bua goes, the tools are associated only with Homo floresiensis."

    The alternative assumption is that hominids made the sophisticated tools themselves, something that contradicts their allometry. So I agree with John Hawks:

    "I think the tools are a complete red herring. There is every reason to think that modern humans were on Flores throughout the Liang Bua sequence. After all, modern people were on Australia by 50,000 years ago, and out to New Britain by 35,000. Maybe they bypassed Flores on the way, but it seems more likely that it would have been occupied long before these more far-flung locations.

    Therefore, it is simplest to assume that modern humans made the tools and hunted the stegodon."

    Actually, no I don’t – just with the part about who likely made the tools. Since the tools and stegadon remains were associated with H. Flor., it is actually simplest to assume that they really were the ones using these tools and hunting the stegadons. But given their expected capacities it makes more sense that they acquired the tools or technology from modern humans or a more intelligent hominid that they shared some measure of contact with.

  9. #9 Jason Malloy
    October 13, 2005

    One more thing:

    “The new jaw bone confirms that a few of the features of the skull (the lack of a distinct chin and the unusual roots of the teeth) were probably characteristics of the population, but it does not confirm at all that any individuals other than the one whose skull was found had the reduced brain capacity.”

    This isn’t exactly true. Fair inferences about the size of the brain can be made from just the jaw, since there are clear trends over human evolution in the morphology of the face related to making room for the expanding brain case. This includes the robusticity of the teeth and the flatness of the face. One supposed consequence of the latter is the existence of the human chin, which the fossil lacks. This can be added to the list of converging signals that LB1 was not aberrant.

  10. #10 D. B. Light
    October 13, 2005

    Any opinions on the suggestion of australopithecine affinities? John Hawkes seems to think there’s something to it.

  11. #11 Karmen
    October 14, 2005

    “But given their expected capacities it makes more sense that they acquired the tools or technology from modern humans or a more intelligent hominid that they shared some measure of contact with.”

    Isn’t this rather similar to the argument that the Egyptians could not have built the pyramids alone? Before the city beneath Giza was unearthed, plenty of folks assumed that such architectural feats were beyond the expected capabilities of the people of the day. After some patience, and a little digging in the dirt, we learned better. Why assume there is some alien influence, when the simplest explanation happens to be striking or unusual?

  12. #12 Jason Malloy
    October 14, 2005

    “Isn’t this rather similar to the argument that the Egyptians could not have built the pyramids alone?”

    This feels like an insult. It’s kind of like saying “isn’t this similar to the argument the earth is flat?” instead of actually explaining why the argument is faulty.

    There is a possible mystery in why human-level technology was found along side possible hominids with chimp-size brains. What does this have to do with Egyptology?

    Of course the mystery of the H. Flor. tools is tied up in the argument over whether it is a diseased human or a hominid. Am I to understand that you are arguing that even if it is a tiny-brained hominid, and even if it did have contact with humans, it is more reasonable to assume that it created all the sophisticted technology previously only associated with humans?

    Why do you think this?

  13. #13 Karmen
    October 14, 2005

    “Am I to understand that you are arguing that even if it is a tiny-brained hominid, and even if it did have contact with humans, it is more reasonable to assume that it created all the sophisticted technology previously only associated with humans?

    “Why do you think this?”

    There has yet to be any evidence to suggest that H. floresiensis had any contact with modern humans. Even if they had, from my experience, humans tend to be somewhat suspicious and xenophobic. So, it seems like more of a stretch to assume, without evidence, peaceful trade between these groups, than to assume they made the tools by themselves.

    “This feels like an insult. It’s kind of like saying “isn’t this similar to the argument the earth is flat?” instead of actually explaining why the argument is faulty.”

    I apologize if you found my analogy insulting; that wasn’t my intent. (Although, in an earlier comment, you indicated that you were seeking passionate debate on this topic… what could be more so than those classic Copernican accusations?)

  14. #14 Jason Malloy
    October 14, 2005

    Although, in an earlier comment, you indicated that you were seeking passionate debate on this topic

    Touche :) What I meant is that it was a cop-out.

    ” So, it seems like more of a stretch to assume, without evidence, peaceful trade between these groups, than to assume they made the tools by themselves.”

    Well, trade specifically may be speculative, but assuming a chimp-brained hominid made tools of a sophistication that is only associated with large brained modern man in the fossil record isn’t just without evidence but actually conflicts with evidence – which is worse. And it appears even more strange to assume since we know modern man was around and in the area during the period the sophisticated tools were found.

    To use an analogy, it would be like if we discovered a new uninhabited island, full of chimps and they live in treehouses. It goes against everything we know about chimp intelligence to assume they built these tree houses. So it is sort of an anomaly. But then we discover two more islands near this island, with indigenous human populations and they live in similar tree-houses.

    To me its like you are still claiming it is more reasonable to assume the chimps built their tree-houses.

  15. #15 Karmen
    October 14, 2005

    “Well, trade specifically may be speculative, but assuming a chimp-brained hominid made tools of a sophistication that is only associated with large brained modern man in the fossil record isn’t just without evidence but actually conflicts with evidence – which is worse. And it appears even more strange to assume since we know modern man was around and in the area during the period the sophisticated tools were found.”

    I suppose any speculation at this point is simply that… without further evidence, and without even knowing for sure if we are dealing with a new species or not, all we can do is guess. You could be right, or I could, although, chances are, some new evidence will come to light to have us all scratching our heads over a new possibility. And to be perfectly honest, I rather like the idea of the small H. Floresiensis interacting with modern humans (the concept would make an excellent springboard for a work of fiction, my specialty) …I’m just waiting for more concrete evidence.

    “Touche :) What I meant is that it was a cop-out.”

    I always appreciate someone who forces me to think critically… Too many people folks figure if an argument is well-worded, then it must be true… and such an attitude isn’t very productive. So, thanks for calling it as it is. :)

  16. #16 M Lees
    October 17, 2005

    In response to the comments made by Jason. Please don’t take the following as personal criticism – just a lively debate.

    Jason Malloy wrote:
    ” six mutually reinforcing data points against the pathological human interpretation:
    1) Skeletal anatomy: Hominid. Not human. Not pathological.”

    Which aspects of the skeletal anatomy suggest ‘not human’? I here take human to mean a member of the genus Homo (excluding Homo habilis and Homo rudolfensis, which almost certainly do not belong in the genus – I note some sources do refer to it as Australopithecus habilis, which is a much better fit with the facts). But whether one uses this as one’s definition of human or use some more exclusive definition (such as only Homo sapiens) then there is nothing about the post-cranial skeleton to prove the ‘not human’ claim. Note also that the state of preservation of all the material is very poor – one source compared them to ‘blotting paper’. I’m not entirely sure what to make of that, but it does suggest that until well-preserved remains are found a degree of caution should be exercised in interpreting the finds.

    “2) Skull anatomy: Hominid. Not human. Not pathological.”

    Surely this is the point in question. The absolute size of the cranium at least suggests the possibility of pathology, it depends on what one takes as the point of comparison for what is normal. As for ‘not human’ – the skull is very human-like. Hence its being placed in the genus Homo. The differences in the skull from Homo sapiens may be explicable by being pathological rather than by being a different species. Or it could be a pathological specimen of pygmy race of Homo erectus(!).
    The relationship between the robustness of the skull and brain size is not clear cut – consider Neanderthals with skulls notably more robust than modern man, but with a larger average brain size. The same could be said for ‘flatness’ of face. Human races today do not all have equally flat faces, but there is no proof that this has any correlation with brain size. Neanderthals also had faces less flat than those of many modern humans. These skull features are not informative in this context.

    “3) Brain size: Hominid. Not human. Not pathological.”

    Once again this is the point in question – see my response to 2 above.
    It is worth noting that in general while insular forms of many mammal species undergo some degree of dwarfing, it seems that the dwarfing of the post-cranial skeleton is normally proportionately greater than that of the brain. Whereas if the ‘Homo floresiensis’ skull is not pathological the opposite would appear to be true. This is one more piece that on balance suggests the skull is pathological.

    “4) Brain structure: Hominid. Not human. Not pathological.”

    The paper that reported this does on-the-face of it tend to support the assertion. However the interpretation of the findings has been challenged – I don’t know the details of the challenges, so I will not comment on how valid or otherwise they may be. At the moment I think the safest conclusion is that the scans indicate a brain structure not typical of modern humans and which appears also to differ from what is expected of a specific pathology.

    “5) Multiple skeletons (including another jaw): Hominid (evidence against pathology).”

    The only thing that the other skeletons prove is that the body size of the specimen was not anomalous. I don’t think this is controversial. The existence of pygmy populations is no big surprise. Pygmies exist today, and there is good evidence that a number of no-longer extant pygmy populations once existed in south-east Asia. The Post-cranial material provide no support what-so-ever for the normality of the single known skull.
    The jaw could provide some support for the pathological nature of the skull since clearly there is a relationship between the size of the jaw and that of the skull as whole – it must fit to work! But there is no such direct mechanical relationship between jaw-size and cranial capacity. Look at the size of the jaws of Paranthropus in relation to brain size. Though I do not know the exact details of the size of the jaw, my understanding currently is that it is compatible with both theories about the status of Homo floresiensis.
    The other features of the jaw are very interesting, but in no way support the idea that the anomalously small cranium was typical of the population. The occurrence of a chin is very characteristic of modern Homo sapiens, but the degree of development is variable and generally not clearly linked to brain capacity. Interestingly though there is some evidence in modern man of inbreeding resulting in reduced development of the chin, I suspect that was specific to the circumstances though.

    “6) Furthermore, just by simple statistical reasoning, we know that non-pathological organisms of a species are going to greatly out-number those with extreme deformations, meaning that fossils of the former are much more likely to be found. For this reason, and given the small number of fossils samples of any species that are likely to be preserved, I think fossil explanations that rely on claims of extreme and unique pathology have a much larger burden of proof, making this interpretation of H. floresiensis even less likely. Why should we begin with inherently less likely assumptions?”

    This is a weak argument. I note a tendency to fall back on parsimony whenever the evidence is inadequate. But if we are going down the parsimony route, try this:
    We know that Homo sapiens and Homo erectus exist (or existed), and that in the case of Homo sapiens pygmy populations exist (and were more common in the past). Apart from the skull in question none of the features of the specimens concerned would cause a new species to be set up (the differences in the jaw should not be overplayed). Therefore the most parsimonious explanation is that Homo floresiensis is just a pygmy race of Homo sapiens, and the skull is pathological. The next most parsimonious explanation is that Homo floresiensis is just a pygmy race of Homo erectus, and the skull is pathological. Next after that is that Homo floresiensis is a pygmy derivative of either Homo sapiens or Homo erectus, and that the skull may or may not be pathological (the comment on point 3 and the tools mean that even if deemed a separate species there remains some reason to think that the skull could be pathological).

    The problem with appeals to parsimony is that it is highly dependent on one’s starting point. Assumptions and viewpoint shape what one sees as most parsimonious.

    The tool situation also fits this picture. The situation is that the tools were found with the ‘Homo floresiensis’ remains. But the brain capacity of the single known skull is not considered consistent with having manufactured the tools. There is no evidence of modern man or Homo erectus having been in the cave around that time.
    This evidence could have several explanations:
    1. ‘Homo floresiensis’ did make and use the tools and the skull is pathological.
    2. ‘Homo floresiensis’ did make and use the tools, the skull is not pathological and is typical, and we are mistaken in our estimations of the relationship between brain capacity and intelligence/ability.
    3. ‘Homo floresiensis’ did not make and use the tools, the skull is not pathological and is typical, the tools were left there at some point by modern man.
    4. ‘Homo floresiensis’ did not make the tools but did use them, the skull is not pathological and is typical, the tools were made by Homo sapiens but were obtained by some means from them. This means that is incapable of manufacturing the tools but is capable of ‘obtaining’ and using them. Some have suggested that they may have traded for the tools – the idea that they were intelligent enough to trade successfully with modern man, but couldn’t make their own tools seems somewhat bizarre.
    Which of these is the most parsimonious? I think the first by a massive margin, but depending on your viewpoint you may differ. Option 4 seems to me by long way the least parsimonious – requiring more things for which there is no supporting evidence.

    In short, the six ‘mutually reinforcing’ points do not mutually reinforce, and none of them stand up on their own. Only the fourth point is actually significantly supportive of the case for the skull being non-pathological, and even this is far from conclusive. I would suggest that points two and three are simply assertions of the very point at issue, point one is wrong, point five irrelevant to the issue and point six is an opinion (with which I disagree) on which of the competing options is most parsimonious.

    So what is Homo floresiensis? – I don’t know, and neither does any one else. I’m inclined to think it was a pygmy population of Homo sapiens or Homo erectus. Depending on one’s concept of ‘species’ it may have warranted the status of a separate species. Which ever of these is true it is probable that the single known skull is pathological – this fits best with the tools, the usual pattern of insular dwarfism, etc. But the reality is there is not enough evidence to be sure. If we find further skulls that show the same characteristics this would strongly support the idea that it is not anomalous. What we have got doesn’t.

    I come back to a point I made in my previous posting – the problem is that people want to believe in it (I’m not clear why, but the reactions to the find make it evident that it is so) and that is clouding judgement. But makes for great fun in arguing the case!

  17. #17 Jason Malloy
    October 18, 2005

    Homo erectus fossils have been found on Flores, dating back 800,000 years.

    Carl, no one has uncovered any erectus fossils on Flores, only the stone tools associated with erectus.

    Morwood, M. et al. 1998. Fission-track ages of stone tools and fossils on the east Indonesian island of Flores. Nature 392: 173-176.

  18. #18 Brian S.
    October 18, 2005

    Re:
    “2. ‘Homo floresiensis’ did make and use the tools, the skull is not pathological and is typical, and we are mistaken in our estimations of the relationship between brain capacity and intelligence/ability.”

    Do we know whether the latter part of that statement is correct? Take modern humans sufferring from microcephalism – do they have the intellectual capability to make tools like those found in Flores?

  19. #19 austin pierce
    November 2, 2005

    I am a hobbit.

  20. Is the Hobbit related to Pygmy race?
    I found some interesting articles on the Hobbit discussing where he may have come from.
    They were on a website about UFO’s of all places, but interesting just the same.
    You can find them on http://ufo.whipnet.org
    It’s huge site and has a ton of pics too.

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