john hawks weblog

paleoanthropology, genetics and evolution

Flores

  • Is that a Jethro Tull song?

    Thu, 2005-12-08 20:32 -- John Hawks

    January's Discover magazine came in the mail; it has a list of the top 100 science stories of 2005. There are several paleoanthropology-related stories that I'll probably share later. But number 91 attracted special attention:

    Flores Man Denied Status As New Species

    Poor Flores Man just can't rest in peace. All year a controversy has raged about whether the bones found in 2003 on the remote Indonesian island of Flores represent a new species. Australian paleoanthropologist Peter Brown insists the skeleton is a new type of human who should be called Homo floresiensis. Others say he's [sic] simply a pygmy, five feet tall, who had microcephaly, a condition that results in a small, oddly shaped skull.

    That's why Robert Eckhardt, a paleoanthropologist at Pennsylvania State University, and a team have intently analyzed the 18,000-year-old bones. The group's research papers, undergoing peer review, are unequivocal. "Homo floresiensis," says Eckhardt, "is not a valid new human species."

    Brown is dismissive. "Robert Eckhardt is thick as a plank," he says....

    Wow.

    The short piece goes on to discuss the custody of the bones and the damage to them.

    Tags: 
    Flores
    scientists behaving badly

  • Give those hobbits a Vegemite sandwich

    Wed, 2005-12-07 20:59 -- John Hawks

    From The Australian:

    THE tiny hobbit-like humans of Indonesia may have lived in Australia before they became extinct about 11,000 years ago.

    The startling claim comes from archaeologist Mike Morwood, leader of the team that in 2003 uncovered remains of the 1m-tall hominid at Liang Bua cave on Indonesia's Flores island.

    ...

    "This is seriously being discussed now by the archaeological community in Australia as a result of our work in Indonesia," Professor Morwood said.

    He suggested that further field work at sites in Indonesia and northern Australia could provide answers.

    I can think of one answer... (via Gene Expression).

    Tags: 
    Flores
    Australia

  • Hawks in Slate on blogging and tenure

    Thu, 2005-11-17 13:18 -- John Hawks

    If you've found the weblog from this Slate article by Robert Boynton, welcome! Take a look around!

    The article launches from the recent tenure denial Daniel Drezner at the University of Chicago to a more general discussion of whether blogging is helpful or harmful to an academic career.

    Here's the basic question:

    But academics aren't just concerned about the public display of an applicant's personal eccentricities. Many perceive blogs as evidence of a scholar's lack of seriousness. Shouldn't he be putting more time into scholarship, they wonder, and less into his blog? And if a blogger does have something serious to say, why is he presenting it in a superficial medium, rather than a peer-reviewed journal?

    In the article, that paragraph links to this Drezner post that among other things, calls blogging about one's own research "an unalloyed good". Good, yes; wise, maybe --- although advocating one's own research necessarily may involve candid opinions of others' research, which many people take less-than-kindly to.

    The article says some nice things about me:

    To take only one other example, John Hawks, an assistant anthropology professor at the University of Wisconsin at Madison, posts three to five essays a week on subjects like evolutionary theory. He writes about science with the breadth of the late Stephen Jay Gould and doesn't see a big difference between most of his online and offline output. "Much of what I write online is scholarly. When I review an issue in human evolution, it is a genuine review. If I criticize something, I back it up," he says. Indeed, his essays are festooned with citations.

    Reading only this week's posts, you might well doubt how "festooned" I am, but please forgive a bit of craziness as my big class gets underway. In the meantime, some more scholarly entries are the Flores file, or this post on mtDNA selection, or the early hominid diet file for some examples.

    Not exactly review papers -- they fill a different purpose. First, I write for myself -- I don't want to forget things before writing them down! That includes reviewing new research, giving additional perspectives, and floating ideas. But from my server stats, the posts are addressing a much larger, while still overlapping, readership from traditional journals. So far this month, I've been visited 25,000 times from over 10,000 different users. I think that's wonderful, and I hope you all keep coming back!

    Hopefully, I'm asymptotically approaching something useful. I do so by keeping things honest, readable, and referenced.

    As far as where blogging is going in academia, there are obviously a wide range of styles. Some academic bloggers touch only lightly on their research interests, some tilt heavily toward advocacy, and a few like mine are adjuncts to traditional research programs.

    Should blogging count in some way? I don't know. I think my blogging makes me a better researcher. If I'm right, it has its own rewards. And I don't think that any blog post approximates a review article in any way -- if they did, they would be a lot less interesting!

    But the cumulative whole is greater than any single review article. And I would say that a sizable number of my posts are "worth" more than a book review, which would get counted in a minor way. It would be nice if the choice between different forms of productivity did not involve such a stark difference.

    Here's Ann Althouse's suggestion:

    If various academic departments are looking for a way to judge writing published in places that are not peer reviewed, I have some advice: Look to the way law schools do their tenure process, because most of what law professors publish is not peer-reviewed. Here at the UW Law School, our tenure process goes through the Social Sciences Divisional Committee and is judged by committee members who serve in departments like Political Science, Economics, and Sociology. You can image how these folks look at the student-edited law reviews where lawprofs publish. But we've developed ways to interact with them. Adapt these techniques for blog-writing that deserves to be treated as research.

    I guess I don't think anything here qualifies as "research" -- I send my research elsewhere, even if I publish pieces of it here first. The question is how to recognize "scholarly" production that is not "research". Some kind of recognition of cumulative authorship is necessary -- just as we currently recognize cumulative (and episodic) editorships, of journals and edited volumes.

    Meanwhile, please enjoy the site, and welcome!

    UPDATE (11/18/05): Daniel Drezner links back with his own reaction to the story. Agreeing with my premise that if blogging adds to research output, it will get counted by traditional means, he suggests:

    So I'm pretty sure that the contribution of blogs to academic output can be measured using pre-existing standards -- with one exception and one caveat. The exception is that maybe the whole of an academic blog is greater than the sum of its parts. Precisely because a blog can contribute to public discourse, scholarly research, and teaching pedagogy at the same time, it encourages a greater mix of ideas and information than would otherwise be possible. Whether this is true I will leave for the commenters.

    I think that's right, and it's what makes blogging much more satisfying than other kinds of non-research scholarship. I'll have more thoughts on it later.

    UPDATE (11/18/05): Orin Kerr at the Volokh Conspiracy also has thoughts.

    Tags: 
    Flores
    metascience
    Neandertals
    Neandertal DNA

  • Paleoanthropology: the new cryptozoology?

    Thu, 2005-11-03 22:38 -- John Hawks

    I got about halfway through this Wired article by Mark Baard about the "resurgence" of cryptozoology, when I found this:

    The media's renewed interest is partly due to the recent discoveries of the "hobbit" remains on Flores Island in Indonesia and the giant squid photographed by Japanese scientists, Coleman said.

    And here is a loaded reference:

    Cryptozoology has been taking its knocks since the discovery of Neanderthal man in the 19th century.

    Many mainstream scientists at the time insisted the remains of Neanderthal were actually those of a sick or deformed human, said Coleman.

    On one side, we have the creationists, who would like you to believe that every evolutionary biologist was suckered by Piltdown. "If they were wrong about that, they can't tell their butts from their elbows!"

    On the other, we have the cryptozoologists, who would like you to remind you of all those bad, bad scientists who thought that Neandertals were sick or deformed. Why, "If they were wrong about that, they can't tell their butts from their elbows!"

    Can't you just hear them? "They doubted us, but the ebu gogo is real! The giant squid is on tape! The truth is out there!

    Can I just ask that future qualifying exams include a butt vs. elbow discrimination quiz?

    Tags: 
    Neandertals
    Flores
    pseudoscience

  • If it weren't for those meddling kids...

    Fri, 2005-10-14 21:04 -- John Hawks

    What accounts for the coincidence of Science publishing the LB1 microcephaly exchange in the same week that Nature published the new Liang Bua bones? I can think of three hypotheses:

    1. The journals simply arranged it long in advance. This would comport with their treatment of the chimpanzee genome announcement, which occurred in Nature but had coordinating papers in Science in the same week.
    2. Science found out about the Nature paper and moved up its commentary to take advantage of the press coverage. This would be relatively easy since the technical comment takes up so little journal space.
    3. Nature found out about the microcephaly exchange and moved up publication of the long-delayed (6 month review) bone paper to beat the press.

    The result of the timing is pretty clear: Nature got a head start on saturating the press, which put out stories on the new bones starting on Tuesday. The first article mentioning the Science exchange appeared on Thursday, and the story has not been widely picked up. Outcome: the vast majority of press accounts emphasize the additional evidence for small body size, but don't include the strongest evidence for pathology published to date.

    This outcome doesn't, of course, necessarily favor any of the above hypotheses, especially since a technical comment cannot expect to get the kind of attention of a regular research paper. And Nature always comes out a day before Science.

    But Tuesday is not a day before Thursday: it's two days. The stories started on Tuesday because somebody broke the Nature press embargo. According to Google News, the first stories to break on Tuesday were from Reuters and from Nature's own online news site.

    So who did it?

    Tags: 
    Flores

  • From one microcephalic to twenty

    Fri, 2005-10-14 21:02 -- John Hawks

    Falk et al. (2005a) compared the LB1 endocast to one microcephalic skull and concluded it didn't match. Now Jochim Weber and colleagues (2005) have compared the endocast to nineteen additional microcephalic modern human crania. They argue that LB1 is likely microcephalic. Falk et al. (2005b) disagree. So who's right?

    Weber et al. (2005) make four points:

    1. The endocranial volume of LB1 (417 ml) is well within the range of the modern human microcephalics (280 to 591 ml).
    2. Modern microcephalic endocasts are "extremely heterogenous" in their morphology, but some of them grossly resemble early hominid endocasts.
    3. One endocast in particular from their sample has a volume of 415 ml, and the ratios of its dimensions are all within 0.01 of the matching ratios from LB1. This appears to indicate an extremely close similarity of overall endocast shape.
    4. A substantial proportion (7 out of 19) of the microcephalics exhibit relative enlargement of Brodmann's area 10, the area that is also extremely enlarged in LB1

    Falk et al. (2005b) criticize the latter two of these points. Taking the last one first:

    Weber et al. assert that seven of their microcephalic endocasts have a relatively expanded Brodmann's area 10 similar to LB1, but none of the five microcephalic endocasts in their figure 3 reproduce the two distinct, enlarged convolutions seen in the region of area 10 in LB1 (Falk et al. 2005b:236).

    Their other criticism focuses on the apparent similarity in ratios between one microcephalic and LB1. This point is somewhat involved, because it relies on a technical difference in the orientation of endocasts. As they describe, the microcephalic pictured by Weber et al. (2005) as well as that pictured by Falk et al. (2005a) both have relatively large cerebellar volume compared to overall brain volume. This results in a cerebellum that takes up a broader area in the back of the endocast.

    I've Photoshopped the figures together to make the orientation clearer:

    Microcephalic skull pictured by Weber et al. (2005) in the orientation of Falk et al. (2005b) (L); Same skull in orientation of Weber et al. (2005) (C); LB1 in orientation of Falk et al. (2005a) (R). For all three, the position of the transverse sinus is marked "TS".

    The disproportionate reduction of the cerebrum compared to the cerebellum in these microcephalics complicates the comparison of endocast shape. For Falk et al. (2005b), the main implication is that an incorrect orientation may result in an incorrect measurement of endocast dimensions, and thereby to incorrect ratios of those measurements. The end result may be that the "closely matching" ratios may not be so close.

    On the other hand, the shape of the forebrain in these endocasts is still broadly similar, and the size of the microcephalic is if anything smaller than LB1. Thus, the disagreement comes down to anatomy, and questions that cannot be answered by ratios.

    For example, even though the cerebellum of LB1 appears relatively small compared to those of the microcephalics illustrated in these studies, it actually appears relatively large compared to humans, Homo erectus and chimpanzees pictured in Falk et al. (2005a). Is this a consequence of allometry, or is it actually abnormally large relative to brain size? Are there microcephalic crania whose cerebellar size is more similar to LB1? Are there any modern humans that have pronounced area 10 convolutions like LB1?

    What I think

    I'm not sure we will ever have answers to some of these questions, at least those requiring comparison to microcephalic crania.

    Of course, there is at least one kind of "smoking gun" proof: if we find another endocast of similar size. Unless another small-brained specimen were found in a death embrace with LB1, the existence of a second small endocast by itself would be enough to show that a small-brained population really existed.

    But is there any other kind of smoking gun evidence? Suppose for example that we found a modern microcephalic skull in a museum that was identical to LB1. Would that be enough to prove the skull was pathological?

    As Weber et al. (2005) note, some microcephalics approximately have the shape of early hominid endocasts. Even if it were pathological, LB1 is clearly one of those: its shape is grossly similar to that of H. erectus, although much smaller. This similarity may have been overstated, since the proportions of individual parts of the endocast surface and the details of its surface have not been reported fully. But considering the extensive variability of normal modern human endocasts, we should expect a range of variability in fossil endocasts as well. Thus, LB1 may well lie within the range of shapes of several early hominid species, even though it does not match those populations in size.

    So as long as LB1 is plausibly within the shape range of early hominids, even a perfect match with some microcephalic cranium is unlikely to convince some people that it is pathological. No smoking gun there.

    At the same time, I don't think we should expect to find an identical microcephalic anywhere. Weber et al. (2005) write that microcephalic crania are "extremely heterogenous", and this would be my assessment also from the few I have seen. Microcephaly is a developmental pathology with many causes, many different manifestations, and consequently many different morphological possibilities. To me, this means that no two microcephalics may be alike, and we may never find an exact match for any ancient microcephalic skull.

    For this reason, the idea that we should expect to find an exact match is far too stringent a requirement. After pointing out the possible discrepancy of orientation, and noting that none of the endocasts studied by Weber et al. had exactly the pattern of area 10 convolutions as LB1, Falk et al. (2005b) end their comment:

    If this is the best evidence that can be produced from a sample of 19 microcephalics, we suggest that the authors reconsider their position on the microcephalic hypothesis regarding Homo floresiensis.

    I have the opposite opinion. I might well expect to study several hundred microcephalic crania and never find an exact match for LB1. Even so, if this sample, like the 19 studied by Weber et al. (2005), has over 30 percent of endocasts with enlargement in Brodmann's area 10, and if it has some endocasts that are relatively broad with low transverse sinuses, it would be hard to say that LB1 lies outside their range of variability.

    One may reasonably wonder where the burden of evidence lies in this case, particularly now that we have additional evidence for small-bodied individuals in the Liang Bua sample. Some may presume that the hypothesis of pathology for the endocast must be accompanied by a specific diagnosis that matches the details of the entire skeleton. After all, microcephaly is a very rare condition, and it must be the rare case indeed that survives in a Late Pleistocene population and exhibits morphology that is broadly similar to that of early hominids.

    But the hypothesis that the specimen is a normal member of a dwarf population of H. erectus, H. sapiens, or Australopithecus brings its own strong problems that we should not gloss over.

    • If it derives from Homo sapiens, what pattern of selection caused its brain to shrink? What accounts for its limb proportions and strange long bone, pelvic, and mandibular morphology?
    • If it derives from Australopithecus, how did it get there? How did it survive so long? How did it get human-like teeth?
    • If it derives from early Homo, none of these questions have good answers.

    So pathology solves a lot of problems with the sample, even if it creates others. I don't know that we can weigh these options relative to each other: the likelihood of microcephaly versus the likelihood of a "Lost World" australopithecine scenario, for example. But if we are going to act like Sherlock Holmes, we will have to start eliminating options. And Weber et al. (2005) do a good job of showing that we can't yet eliminate microcephaly.

    UPDATE (10/14/05): A lot of readers have come away with the impression that I am strongly advocating the microcephaly hypothesis. What I have tried to do over the course of several posts is not to advocate for microcephaly, but instead to explain why the microcephaly explanation may not yet be rejected.

    If I am an advocate for anything, it is for a full airing of these issues, and a more public presentation of original data. In the Reuters article on the new bones, Robert Martin says:

    "This paper doesn't clinch it. I feel strongly that people are glossing over the problems with this interpretation."

    A lot of people feel that way. There is nothing to be done but more research, more comparisons, and more access to results.

    References:

    Falk D et al. 2005a. The brain of LB1, Homo floresiensis. Science 308:242-245. Full text (free)

    Falk D et al. 2005b. Response to comment on "The brain of LB1, Homo floresiensis". Science 310:236. Full text (subscription)

    Weber J, Czarnetski A, Pusch CM. 2005. Comment on "The brain of LB1, Homo floresiensis". Science 310:236. Full text (subscription)

    Tags: 
    Late Pleistocene
    Homo erectus
    Flores

  • Flores update, October 2005

    Tue, 2005-10-11 23:20 -- John Hawks

    This week's Nature is carrying a paper by Morwood, Brown, and colleagues (2005) presenting additional skeletal material from Liang Bua as well as a commentary by Daniel Lieberman. Thanks to a reader, I found the permission slip from Nature lifting the embargo, so I can let fly without bogarting the kind journalist who forwarded me the paper.

    What is noteworthy about the new bones?

    The paper discusses three important specimens. The first is the adult mandible LB6/1. In its overall size and morphology it is similar to the mandible of LB1, reported last year. Like LB1 it lacks a chin and Morwood et al. (2005:1013) compare its symphyseal morphology to Dmanisi D211. Overall, the mandible is slightly smaller in tooth size and corpus size compared to LB1, and its ramus is quite a bit shorter.

    LB6/1 is part of a partial skeleton. The other elements are not described in the paper, but they are listed: a portion of proximal ulna, a partial right scapula, a foot bone, one each of finger and toe bones, and a complete radius 157mm long. That's a short radius -- barely more than 6 inches. It was broken during life and healed.

    Wait a minute. Did you say a 6-inch long radius?

    Funny how nobody else seems to have picked up on this yet.

    The authors estimate a brachial index (radius to humerus) for LB1 of 78 percent, estimating likely radius length from the ulna. This would put LB1 within the range of "tropical" human populations. If the LB6 individual had the same "tropical" brachial index, its humerus would be around 200mm long. That's 43mm shorter than LB1.

    This admits a couple of explanations:

    1. LB6 was simply a smaller individual than LB1. The mandible is more or less consistent with this hypothesis, which may therefore be the most likely.
    2. LB6 did not have the unusually long arms of LB1. Where LB1 is australopithecine-like, perhaps LB6 was more humanlike. This seems less likely, but it would be consistent with the idea that the proportions of LB1 represent some kind of pathology.

    Wait a minute. Did you say australopithecine-like proportions?

    Yes, the LB1 humerus and ulna are relatively long compared to the femur:

    For example, the humerofemoral index of 85.4 is outside the range of variation for H. sapiens, but is the same as AL 288-1 A. afarensis, and midway between the indices for apes and humans. The more complete left ilium [pelvic bone] also indicates that the pelvis is flared antero-laterally, consistent with an australopithecine-shaped thoracic region. Body proportions of LB1 are the same as AL 288-1 A. afarensis, but differ from all other hominins for which they are reliable data, including H. erectus (Morwood et al. 2005:1016).

    "Outside the range of H. sapiens" is also outside the range of any Pleistocene human, by the way.

    Didn't you say this was an australopithecine when it came out a year ago?

    Well, yes. My first post on the subject was titled, "Liang Bua: an australopithecine from Flores?" And I did present a rationale for believing that the skeleton was australopithecine rather than Homo. My point initially was that the combination of small body size and relatively small brain size was very simple to imagine as a descendant of an australopithecine, but very difficult to imagine in a descendant of Pleistocene Homo.

    Some other features of the skeleton resemble Australopithecus. None of them individually is sufficient to label the skeleton as australopithecine, but together they are suggestive. For example, the pelvis is broad, with a very prominent anterior superior iliac spine. It's very similar to australopithecines like AL 288-1 (Lucy) or Sts 14.

    But we don't know to what extent the breadth and morphology of australopithecine pelves are consequences of their phylogeny as opposed to allometric consequences of their small body sizes. In other words, LB1 might look australopithecine-like because it is small, instead of actually being an australopithecine.

    The postcanine teeth are relatively large for a human, but they are far from australopithecine-like in size. Aside from their size, the first molars are the largest; just the opposite of the australopithecine condition. The roots of the premolars are completely uninformative, since both australopithecines and early Homo have the bifurcated roots found in both Liang Bua mandibles. So if this was an australopithecine-derived population, it had evolved considerably smaller teeth. Happily, this evolution of smaller teeth might also account for the gracile, Homo-like facial morphology.

    OK, so it's an australopithecine, right?

    Maybe. It would not only have to be an australopithecine; it might have to be a DWARF AUSTRALOPITHECINE.

    Consider that the femur length of LB1 is just a millimeter shorter than Lucy and its body proportions are basically the same. Lucy (AL 288-1) is not only the most complete known australopithecine skeleton (barring STW 573, which is yet to be described), it has the smallest limbs. There are some individual bone fragments with smaller dimensions than Lucy's, but not very much smaller. At the same time, there are many larger specimens. Some of these, like the Sibilot radius KNM-ER 20419, are a whole lot larger.

    Now at Liang Bua, LB1 is nearly the biggest specimen. Brown et al. (2004) do report another radius from an older part of the deposit with an estimated length of 210mm. Again assuming the same brachial index, this would correspond to a humerus of 269mm, around an inch longer than LB1.

    But the other two adult long bones reported are the LB6 radius (157mm) and the LB8 tibia. At an estimated 216mm, this tibia is substantially shorter than the 235mm LB1 tibia. There is no comparably complete australopithecine femur, but if Lucy (missing around a third of the shaft) was around the same length as LB1, then LB8 would be shorter than any australopithecine.

    Even worse, it is shorter than all but one of 47 chimpanzee tibiae in my comparative data. That's really short.

    So as it stands, it appears that the Liang Bua sample is substantially shorter than australopithecines. At the same time, remember that the brain size of LB1 (estimated by Falk et al. 2005 as 417 ml) is smaller than all but three australopithecines (KNM-WT 17000, AL 162-28, and AL 333-105). Together with the facial and tooth reduction, this is good evidence for selection for smaller size in an australopithecine-like population.

    OK, so that rules out any chance that it is a dwarf modern human population, right?

    Probably. This would have to be an exceptionally short sample of an exceptionally short population. But then it partly depends on how accurate the stature regressions are. As you get to the bottom of the size range of skeletons from which a regression is calculated, you get less accurate body size estimates. And the proportions affect the estimates. These deserve to be gone over carefully.

    And there is no reason in principle why a modern human population could not have been smaller than any pygmy populations of today.

    There are two stumbling blocks to the hypothesis that this sample represents a dwarf modern human population. The first is the fact that neither mandible looks modern. It is very hard to argue that the features of these mandibles are the consequence of small body size alone; they genuinely appear archaic.

    The second is the size of the brain.

    Speaking of the brain, is it small enough to rule out descent from early Homo?

    That's a very good question. Large-bodied early Homo appears to have an average endocranial volume around 800 ml. A reduction in body size to LB1 should not have cut the endocranial volume in half -- we would expect a volume closer to 600 ml. In fact, an average of around 600 ml is just about what we observe for small-bodied early Homo, including H. habilis in Africa, and possibly including the Dmanisi sample of early Homo from the Republic of Georgia.

    To get from a habiline-sized hominid to LB1 body size would take relatively little size reduction. This means that the brain size of LB1 would be very surprisingly small for a habiline of its body size (particularly since many habilines are its size, yet have much larger brains).

    So to go from any variety of early Homo to LB1 in brain size would require pretty substantial selection for smaller brains. It is hard for me to see that happening in a hominid population, because it would likely lead to functional compromise of some kind. In particular, if most of the selection for larger brains in hominids has been to promote social intelligence, it is hard to see how selection for smaller brains would happen.

    On the other hand, who knows? There is, after all, the endocast shape, which is Homo-like (Falk et al. 2005). And the facial morphology. And the teeth.

    In the face of all this, Morwood et al. (2005) appear to be persuaded most strongly by the limb proportions. Maybe an australopithecine-like limb ratio is a good phylogenetic indicator, but considering the recent spat over early hominid limb proportions in Current Anthropology, this might not be the best hook to hang your hat on.

    Didn't you say six months ago that LB1 is pathological? Well, what do you say now, smarty-pants?

    I still think it's pathological. We have so far seen a few of the details that point to that conclusion. For example, there's the low torsion of the humerus. "Torsion" refers to the angle between the axis of the head and the axis of the distal end of the bone. The humerus of LB1 is unlike any hominid. It's unlike any great ape. It's like monkeys and gibbons. That's weird. Then there is the bowed tibia, and the rotated premolars, all clearly in the reports so far.

    We will see if these and other features can be combined into a single diagnosis of pathology, one that possibly includes the small size of the brain or details of its endocast morphology. For myself, I think there is sufficient evidence to question whether LB1 is characteristic of its population.

    Now we have additional evidence of body size in the population, including the two very short elements described above. Is that enough to believe that the brain is characteristic of the population? If there has ever been a case to invoke the "extraordinary claims require extraordinary evidence" clause, it is this one. LB1 is not only small-brained for a human, it is small-brained for any hominid.

    So I don't think that pathology is a magic wand that is going to make this population into ordinary modern humans. But I'm not ready to jump to the conclusion that this was a population of hominids with australopithecine-sized brains. There is, after all, the problem of how they got to that island in the first place.

    Speaking of getting to the island, what about their technology?

    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. Maybe they hunted the hobbits. Maybe some of the bones at the site are modern humans. Maybe some of them were dwarf modern humans.

    Seems all tangled up, doesn't it? Yet the behavior speaks to the presence of Homo, and from the character of the tools, modern human seems likely. If those modern humans weren't the hobbits, then they lived alongside the hobbits.

    So what's next?

    We should see before long at least two (and possibly more) papers that dispute the Homo floresiensis interpretation. Carl Zimmer reports at his weblog that one of these will come from Robert Martin:

    "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."

    I think that's right. Of course Martin's interest is allometry of the brain, which made the initial interpretation -- island dwarfing of an early Homo variant -- seem very unlikely from the start. An australopithecine origin is less problematic from the point of view of allometry, but introduces the problems of biogeography -- how did they get there, and why weren't they anywhere else? Pathology would help a lot to explain that brain....

    The pathology work will be the most interesting; I know there are many people working very hard to find a single pathology explanation that is consistent with the anatomy of LB1. If they have succeeded (and we should find out before long) it will be a major accomplishment.

    And there will be comparative anatomical and possibly genetic work on pygmy people in the region. Remember the Rampasasa Pygmy Somatology Expedition? It will be coming to a journal near you.

    The stealth factor is whether Max Planck (or anybody else) has gotten any DNA out of the bones. Wouldn't it be interesting if part of the mtDNA sequence looked like one of the more ancient human-specific nuclear genome mtDNA inserts (numts)? If this is an australopithecine population, mtDNA would be enough to show it.

    More information here

    All the Flores files

    Original discovery

    Endocast study

    The damage to the specimens

    Myth of the ebu gogo

    References:

    Brown P, Sutikna T, Morwood MJ, Soejono RP, Jatmiko, Saptomo EW, Due RA. 2004. A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. Nature 431:1055-1061.

    Falk D, Hildebolt C, Smith K, Morwood MJ, Sutikna T, Brown P, Jatmiko, Saptomo EW, Brunsden B, Prior F. 2005. The brain of LB1, Homo floresiensis. Science 308:242-245. Full text (subscription)

    Morwood MJ, Brown P, Jatmiko, Sutikna T, Saptomo EW, Westaway KE, Due RA, Roberts RG, Maeda T, Wasisto S, Djubiantono T. 2005. Further evidence for small-bodied hominins from the Late Pleistocene of Flores, Indonesia. Nature 437:1012-1017.

    Tags: 
    Late Pleistocene
    Homo erectus
    Flores
    Dmanisi
    Homo habilis
    A. afarensis

  • News trickling about Liang Bua

    Tue, 2005-10-11 10:43 -- John Hawks

    I am seeing news reports this morning about this week's upcoming paper in Nature about the Homo floresiensis bones.

    The paper is supposed to be under embargo until tomorrow afternoon; Nature is reporting on it early under its pay-per-news site; Reuters has a short article, and New Scientist has a longer one (Google says subscription-only, but once again I got it without a subscription).

    Here's my favorite quote from Reuters:

    The newly found remains, dug up in 2004, consist of a jaw, as well as arm and other bones which the researchers believe were from at least nine individuals.

    That's right, we're going back ... TO THE FUTURE! Here it's not even so bad -- I mean, these bones were found just last year. Just wait until they have to report on future past discoveries.

    I'm keeping the embargo, so you can expect to see my review of the papers tomorrow afternoon. Yes, that's right -- this humble blog is keeping its word while MSM giants break theirs. Anyway, come back tomorrow for the real story.

    In the meantime, enjoy this quote from New Scientist:

    And in the light of the new finds, Morwood's team is itself moving away from the dwarfing theory. The hobbits have disproportionately long arms relative to their legs, and so cannot be scaled-down versions either of modern humans or Homo erectus, who have had the same body proportions for 1.6 million years.

    Ancestral line

    They say that a more likely ancestral line goes back to australopithecine species such as 3-million-year-old "Lucy", found in Ethiopia (Australopithecus afarensis).

    "The combination of skeletal attributes that [the hobbits] share is not found in any modern human," says team member Peter Brown. "The bones of the hands and feet don't look like those of arboreal apes, but like everything else to do with Homo floresiensis, they are not like humans either."

    I'm certainly enjoying it.

    Tags: 
    paleonews
    A. afarensis
    Homo erectus
    Flores

  • Hobbit backlash building

    Fri, 2005-09-23 00:11 -- John Hawks

    The BBC ran a show tonight (Thursday Sept. 22) on the Liang Bua discoveries from Flores; meanwhile BBC News is reporting a few more details about the pathology claims:

    Jacob was soon joined by a handful of researchers in the belief that the discovery team had happened upon nothing more than a member of our own species with a rare disease.

    Professor Bob Martin, one of the team that is set to publish new evidence challenging the discovery team's original interpretation, says the Hobbit's brain is "worryingly" small and contradicts a fundamental law of biology.

    ...

    Ann MacLarnon of Roehampton University, UK, has discovered the skull of a microcephalic in the vaults of London's Royal College of Surgeons with a brain that matches that of the Hobbit for size.

    "It showed that we really could demonstrate with a specimen that [microephaly] could explain the Hobbit's small brain," she told Horizon.

    Along with the others who have already come out publicly, like Maciej Henneberg and Alan Thorne --- and of course Teuku Jacob --- this is starting to seem like a rather large team of experts arrayed on the anti-floresiensis side.

    "Set to publish new evidence" sounds good; we should see this coming out soon.

    Meanwhile, there is the problem of the second mandible:

    "Let's buy into [the sceptics'] argument just for a bit of fun," said Professor Bert Roberts of the University of Wollongong, Australia, a member of the discovery team.

    "We've got a complete lower jaw that's identical to the first so there we have a situation where we've now got to have two really badly diseased individuals.

    "We've got a diseased population like some sort of leper colony, living in Liang Bua 18,000 years ago. The probabilities have got to be vanishingly small."

    This may become the most intensely studied pair of jaws ever. Are they really so similar? Remember that the second jaw hasn't yet been published. From the pictures, it looks if anything a bit smaller than LB1, and strange --- although not in precisely the same way. Are they both "badly diseased individuals"?

    I'd say it's at least as likely as that skeleton being normal.

    Tags: 
    Flores

  • Flores interviews on NOVA scienceNOW

    Fri, 2005-09-16 11:49 -- John Hawks

    I hadn't run across it before, but PBS ran a segment on the Liang Bua fossils in April. There is a webpage where you can watch the TV segment. You can also "compare the brains" (warning: requires QuickTime).

    Whose opinion do we want?

    The PBS site has a question-and-answer session between viewers who submitted questions and Bert Roberts, one of the discovery team. The segment also has clips of interviews with Ralph Holloway and Teuku Jacob, for which PBS does not provide full text.

    And, guess who else they brought in to talk about the discovery?

    Jared Diamond.

    Now, if you're a regular reader you may think I'm a Diamond-hater, but it's not true. I really like Jared Diamond. I used to think he was the best science writer, and this was back when I got Discover as a kid. So I grew up with Jared Diamond. It's just lately -- when he started writing about social anthropology and archaeology -- that I started having some doubts (here, here, and here).

    Consider this quote from the transcript of the scienceNOW segment:

    JARED DIAMOND: My bet is we did not have sex with them. And here's my reasoning. I would have predicted that they would have been really nasty, just like any humans would be really nasty.

    Huh?

    I honestly don't know what to make of that. From the context, it would appear that Diamond actually thinks they would have been hostile toward each other, but even that doesn't make any sense in the context of human history: being nasty has rarely stopped anyone from "doing the nasty".

    Anybody can make wacky assumptions based on their own perception of reality about what early hominids were like. We all "know" about people, after all. But few of us actually stop to think about the difference between "human nature" and the "nature" of people we know. Diamond is one of those who (it seems) ought to know better.

    Interestingly, the host Robert Krulwich, is really good at catching Diamond in contradictions. Like this one:

    Krulwich: ... What do [Komodo dragons] weigh?

    Diamond: Up to 500 pounds. But it's worse than that because while the modern Komodo dragons weigh up to 500 pounds, the archeological excavations that produced the dwarves also produced evidence of a super-size Komodo dragon.

    Krulwich: Oh, so these dragons are getting smaller, too, over time?

    Diamond: No, the dragons are different. Warm-blooded animals shrink on islands. Cold-blooded animals often expand on islands, to fill the niche left by lions and tigers that could not get out there. Cold-blooded animals have lower food requirements, and so a cold-blooded animal requires as much food as a warm-blooded animal one-seventh of its size.

    Krulwich: Oh! So while the mammals are going down, the reptiles could be going up?

    Diamond: It happened there on Flores. Flores has the Komodo dragon, the world's biggest lizard today. But in the past apparently it had a super Komodo dragon.

    So, you're saying the dragons did get smaller over time? Now, of course there were bigger lizards on Flores in the past, and they might be gone because humans are now there. No problem, although they apparently lived alongside some hominids for 800,000 years without too many problems. I'm just not sure this is the best example to use for your "cold-blooded giant, warm-blooded dwarf" theory.

    Could it be that you're trying to shoehorn all these species into a universal rule that they don't -- in this particular case -- fit very well? You could see why someone would be confused.

    Travellers' tales

    Has anybody else noticed the problem with the artist's conception? You know, the one with a grizzled-looking hobbit with the giant rat slung over his shoulder?

    Flores artist's conception, alongside scienceNOW host Robert Krulwich and a pygmy (from PBS website)

    Yes, you guessed it -- the fossil skeleton LB1 is a woman, but the reconstruction is clearly not a woman. If the shrunken and tactfully figleafed version above doesn't convince you, you can see a bigger version here.

    Now, this wouldn't be such a bad thing by itself; I mean, if this really was an ancient human species, then there must have been men.

    But we have no reason to think that the men were necessarily the same size as the women, so presenting a female skeleton in a male reconstruction is clearly misleading about the biology of this "species". And why not show a woman? Because they wouldn't have carried a spear with a giant rodent slung over their shoulder? What does that say about our assumptions about this "radically different" hominid species?

    The answer is clear: presenting a very tiny man instead of a woman exaggerates the differences between them and us.

    It's not just the artist's conception, or the 500-pound super-Komodos: everything about the presentation of this discovery has been tilted to emphasize how strange and nonhuman (perhaps even subhuman) it is.

    Remember medieval travellers' tales? They featured things like the "barnacle goose", which was supposed to hatch from barnacles in trees. And people with no heads and faces on their chests. And furry ape-men.

    Now some of these things turned out to have been based -- however distantly -- on fact, like giraffes and chimpanzees. But the myth and the reality were hopelessly tangled up.

    That is already happening with these "hobbits." Of course, there are the obvious mythological elements -- such as the ebu gogo myth. But there are plenty of other exaggerations: in the transcript of the NOVA scienceNOW segment, every fantasy aspect is emphasized and exaggerated, from the very introduction:

    ROBERT KRULWICH: You're not going to believe this, and I wouldn't blame you, 'cause if I told you this story that..."once upon a time, on a little island, somewhere way off in the sea, there lived a race of teeny people not known to science. They lived with elephants the size of ponies. They hunted dragons that spat poisonous saliva laced with botulism and anthrax..."

    You'd say, "Come on."

    Yes, in fact I would. Especially when we hear things like this:

    ROBERT KRULWICH: And if that's true, brain scientists would have a whole new model for human intelligence, and that's huge.

    A WHOLE NEW MODEL FOR INTELLIGENCE! INCREDIBLE!

    KIRA WESTAWAY: The fact that it came out at 18,000 was pretty much a shock to everybody.

    ROBERT KRULWICH: A shock because that means that these little people were alive during, well, modern times.

    MICHAEL JOHN MORWOOD: We know that modern humans have been in that area for at least 50,000 years.

    ROBERT KRULWICH: So, if you do the math, little people and big people shared this island for over 30,000 years!

    THEY SHARED THE ISLAND FOR 30,000 YEARS! INCREDIBLE!

    JARED DIAMOND: It's spit that contains botulism bacteria and anthrax and other things you wouldn't want to get infected by, really nasty bacteria.

    BOTULISM AND ANTHRAX AND, um, OTHER THINGS, OH MY!

    Please don't misunderstand my sarcasm. If the "hobbits" are really a new species, then they really are very unusual. If they actually had an advanced stone tool technology, and actually hunted down stegodon and Komodo dragons, that is pretty neat.

    But we're a ways from actually deciding that these things are true.

    For one thing, all these "stunning" facts are self-contradictory. If modern humans and "hobbits" shared Flores for 30,000 years, then isn't it parsimonious to assume that modern humans made the "advanced" tools and hunted down the stegodons? Evidence of these "advanced" tools at 80,000 years ago (which we don't, by the way, have) wouldn't even disprove this proposition, since there could easily have been modern humans on Flores that early.

    I give credit to Diamond for figuring this contradiction out:

    But on top of that, people talk about possible coexistence between the micropygmies and modern sapiens for 40,000 years. I don't believe it. My guess is that within 100 years of modern sapiens arriving on the island, the dwarves would have been exterminated.

    But that creates a different problem: how did humans make it to New Ireland and Bougainville by 30,000 years ago, and Australia by 50,000 years ago, without managing to step on Flores on their way?

    For another, all the speculation about the size and organization of the brain assumes that all hobbit brains were the same. Perhaps it's true, but assuming it is clearly building a big story on an insufficiency of data.

    And this isn't even considering the possibility that the specimen is pathological. As you'll remember, my view of the bones persuaded me that they aren't normal. Now, I'm not working on the skeleton myself and I am quite willing to admit that I could be wrong. But there's a lot of hand-waving in these stories.

    The million-dollar question

    Aside from the clip from Teuku Jacob, the segment doesn't really address the question of pathology. There is some reason to think this is by design.

    Consider: the interview with Diamond says this:

    Krulwich: Which leaves us with this other question of, when scientists have now begun looking at endocasts of these brains, they say--well, at least this fellow Ralph [Holloway, an anthropologist at Columbia University] who we talked to -- he says, well, they don't look the same as human brains. There could be two reasons for that. They could be sick human brains, in which case they would look like sick human brains, or they could be something different.

    This would make it look like they asked Holloway about pathology, and he said it might be or it might not be, which I think was his view in April when this aired. But the televised segment does not feature any actual quotes from Holloway about whether there might be pathology.

    Then, there is the "Ask the Expert" section with Bert Roberts. Out of 22 questions, not a single one relates to pathology in any way.

    The most about pathology they allowed to slip into the public domain is this quote from Jared Diamond's interview:

    Diamond: Well, I would bet $10, or 10 to one odds, that they were a separate species and not some deformed, microcephalic [that is, having an abnormally small head] modern humans.

    Krulwich: Why? Because you want it? Because it's a great tale? Or because there's just something in you that says, yeah, the data will deliver?

    Diamond: The data already out there -- well, the skull does not resemble that of known microcephalics. They've got eight different specimens, or fragments of eight different specimens. The recent information on the brain indicates a very distinctive form of brain. The whole form of the skull is erectus-like, and it's not pathological-sapiens-like. So everything says yes erectus and no, not a weird sapiens.

    The thing that concerns me most about the segment is that they clearly had a choice. They could have reported on the controversy over the pathology. I can understand why they might not do that: the people who think that the specimen is pathological haven't yet published their results; their claims haven't been evaluated by other scientists, etc.

    But what they chose to do, instead of giving Jacob (or someone else, like Maciej Henneberg) a chance to present their view of the discovery, they chose to interview a prominent American science writer to contextualize it.

    That's a reasonable choice for their likely viewers, but it has two unfortunate side effects. First, it removes everything from the evidence, because Diamond hasn't seen it, and would be unqualified to comment on it if he had seen it (hence, the silly comments about the brain).

    Second, it raises the issue of exactly what PBS wants here: do they want to discuss the science, or to sensationalize it?

    Because among all the people interviewed for the segment, Jacob is the only biologist who has actually seen the bones! He might be completely wrong, but at least we can presume he knows more about this than Jared Diamond does! Yet this is the full extent of Jacob's remarks presented in the segment:

    ROBERT KRULWICH: "Wait a second," said this well-respected Indonesian anthropologist. Teuko Jacob says, "I think she's one of us, our species, but with a rare disease."

    TEUKO JACOB (Gadjah Mada University): Therefore there's a small brain, microencephaly.

    ROBERT KRULWICH: Microencephaly can severely retard growth in modern people. So she's one of us with a growth disease?

    TEUKO JACOB: I'm sure about it.

    ROBERT KRULWICH: "Well, you're wrong," said the Australian team.

    Oh, well then. Sorry for asking.

    Now, I don't expect anyone to believe what I say or anyone else says about these fossils; you should read the science yourself, and read everything skeptically, no matter what the source. I'm not out there saying why I think the bones might be pathology; it's not my research.

    But it seems to me that these fossils are being interpreted in a way that enhances a narrative instead of in a skeptical light. And that doesn't seem right to me; I don't think it advances our understanding of anything. Especially since following the narrative generates internal contradictions.

    We're impoverished in the U.S. for televised science programming, and PBS is about as serious as it gets (which isn't saying much). So seeing this makes me concerned.

    Tags: 
    Flores
    Homo erectus

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