Flores

A single foot bone from a cave isn't ordinarily very remarkable. But when it's a funny-looking foot bone from a 67,000-year-old site on an island, that gets a little more attention. New in the Journal of Human Evolution, Arnand Mijares and colleagues report on a third metatarsal from a cave called Callao Cave, on the Philippines northern island of Luzon. If the date is right, this is the oldest human bone known from the Philippines, or indeed from anywhere not reachable by land from Asia -- except for the deepest bone elements from Liang Bua cave on Flores.

The presence of a human bone on an island not reachable without a water crossing naturally brings up parallels to the Flores case. The bone's small size provides an additional parallel. Mijares and colleagues compare the metatarsal to a sample of small-bodied Negrito skeletal remains from the Philippines, finding that its dimensions are smaller than any of them. It is smaller in its preserved dimensions than the small metatarsal of OH8, generally assigned to Homo habilis.

Did the bone belong to a hobbit-like creature?

Sadly, there is no direct comparison to the foot bones of LB1, the skeleton from Flores that started the Homo floresiensis craze. This would seem to be another case where the failure to disseminate scans of a specimen has impeded the analysis of new discoveries from other sites. The science suffers for it. The description of the LB1 hindlimb elements by Jungers and colleagues (2009) includes good photos of the MT3 of that specimen, which looks basically humanlike, although small and with a small proximal end in particular.

Human metatarsals have shafts that tend to get thinner as you move from the proximal to the distal end of the bone. The thinning is both in the side-to-side (mediolateral) dimension and in the top-to-bottom (dorso-plantar) dimension. The shaft in humans is relatively straight. Ape metatarsals tend to be very curved, and uniform in thickness from proximal to distal. Monkeys are between these extremes in curvature, although with substantial variability.

The Callao MT3 is humanlike in being relatively straight and thinning from proximal to distal, at least in a mediolateral dimension. But the bone actually gets thicker in the dorso-plantar dimension as it approaches the head. That's not like most human metatarsals. The proximal end and shaft, which are well-preserved, are smaller in this Callao MT3 than in the females of the Negrito comparative sample examined by Mijares and colleagues. The proximal end and shaft are quite a bit smaller than the OH8 third metatarsal. This is a very small bone.

Maybe too small. The metatarsal is reported to be smaller than OH8, with an estimated length just a hair longer than the measured length of LB1 MT3.

I'd have to look at a lot more MT3's to be sure -- which I can't do right now -- but this one looks sort of funny to me. Could it be some other kind of primate? The authors hold out some possibility that the specimen represents a subadult, but if it does, it was very close to being adult based on the preserved anatomy. So it's not a case where the bone was going to grow a lot more. As usual, I wish that the paper included more information about the range of variation in humans and other primates. If we're dealing with an odd specimen, how strange is it in the characters that stand out?

As for dating of the site, a mean of 67,000 years ago is the result of uranium-series dating of two cervid teeth in the same stratigraphic unit as the metatarsal. This method requires the application of a model of uranium absorption over the time since the teeth were deposited. This model is too complicated to describe here; the authors go through several scenarios and conclude that despite the possibility of inaccuracies, the remains are very unlikely to have been deposited as recently as 40,000 years (the approximate age represented by occupation of Niah Cave, Borneo). I have no reason to doubt the dating.

I'll leave open the question of whether a date above 60,000 years ago is unexpectedly ancient for the region. It's interesting, at least. I see nothing impossible about there having been non-hobbit-ish humans in the area at that time, as I think we'll need to revise much about the timing of dispersal of mtDNA lineages from Africa. And don't forget that mtDNA doesn't tell the important story anymore.

But by and large, I want more information on this one.

(CORRECTION: The initial version of this post followed the paper in placing the site east of Wallace's line. Wallace's line actually passes south of the Philippines.)

References:

Jungers, W.L., Larson, W., Harcourt-Smith, W., Morwood, M.J., Sutikna, T., Rokhus Due Awe, Djubiantono, T., 2009. Descriptions of the lower limb skeleton of Homo floresiensis. J Hum Evol 57:538-554. doi:10.1016/j.jhevol.2008.08.014

Mijares AS, Détroit F, Piper P, Grün R, Bellwood P, Aubert M, Champion G, Cuevas N, De Leon A, Dizon E. 2010. New evidence for a 67,000-year-old human presence at Callao Cave, Luzon, Philippines. J Hum Evol (in press) doi:10.1016/j.jhevol.2010.04.008

A new paper is pushing back the time of initial occupation of Flores by hominins to at least 1.0 million years ago. Adam Brumm and colleagues (2010) are reporting that they've found stone tools in a site from the Soa Basin of Flores, the same geological region as the previous site of Mata Menge.

The Wolo Sege excavation yielded no faunal remains, but 45 in situ stone artefacts were recovered from the conglomerate and two fine-grained metavolcanic flakes were excavated from the lower tuffaceous siltstone layer ~15–20 cm above the Ola Kile Formation (Fig. 3e, f). A single volcanic flake was also recovered from the upper overbank deposit during extraction of sediment for dating. The Wolo Sege stone artefacts are predominantly small and morphologically undifferentiated flakes struck from cobbles by direct hard-hammer percussion (Fig. 3; see also Supplementary Fig. 2), but include a bifacially and centripetally worked ‘radial’ core, similar to those characteristic of the Mata Menge assemblage of stone artefacts.

The radial core is not illustrated, but several of the flakes are figured in the paper. The conglomerate in question is overlain by a layer with a minimum date of 1.02 million years.

A date of 880,000 years ago for human occupation made for a convenient explanation of faunal turnover on the island, which happened around that time. The turnover included the extinction of the small pygmy stegodont species Stegodon sondaari, which was replaced in later faunal assemblages by the Java-derived Stegodon florensis. It also included the extinction of giant tortoises.

This suggests that the non-selective, mass death of S. sondaari and giant tortoise, associated with stratigraphic evidence for a major volcanic eruption at Tangi Talo ~0.9 Myr ago10, could represent a localized or regional extinction, and that the faunal turnover may have been a result of climate change, volcanic activity or some other natural process or event (Fig. 5).

I discussed this with my graduate seminar yesterday. The long persistence of this toolmaking culture, in what must have been a rather small human population, is weighing on my mind. Were there recurrent contacts from Java, keeping the population going? How dependent were these people on their tools?

Hominin predators can lead to unstable dynamics -- most predators will undergo predator-prey cycles, but humans can switch to other resources and continue to press a small prey species to extinction. The long persistence of tasty animals on Flores in the presence of hominins suggests that the subsistence practices of these hominins were different in some ways from later humans.

This finding doesn't really help us to resolve the issues of the later Flores record, including the relationships of the skeletal individuals with other hominins. There's been some press about the hobbits lately, but it's all paleoanthropological tree-marking -- except for the news that they'll be reopening excavations at Liang Bua.

References:

Brumm A, Jensen GM, van den Bergh GD, Morwood MJ, Kurniawan I, Aziz F, Storey M. 2010. Hominins on Flores, Indonesia, by one million years ago. Nature (advance online) doi:10.1038/nature08844

Elizabeth Culotta reports from the Stony Brook hobbitrama:

The meeting was a rare chance for U.S. researchers to hear from the team that discovered the hobbits, which they officially call H. floresiensis. Lead excavator Thomas Sutikna of the National Research and Development Centre for Archaeology in Jakarta and Mike Morwood, now of the University of Wollongong in Australia, flew across the globe for the meeting, which gathered only those researchers who already accept H. floresiensis as a new species.

One piece of news: Matt Tocheri found another capitate among the bagged bone fragments:

The bone has the same peculiar and primitive configuration seen in the capitate of the main skeleton, suggesting that at least two individuals from Liang Bua have this oddly shaped wrist bone.

I think Culotta's short description gives a good flavor of the conference. The webcast version, which I mentioned earlier in the week hasn't shown up in the archive at Stony Brook. But two of the Richard Leakey symposia have video available (Link to archive), which might be interesting viewing.

I started one of them, and the Stony Brook provost introduces the symposium by noting that they wanted their series of symposia to include specialists with strong differences of opinion, with the hope of making progress toward defining the critical issues.

I guess somewhere along the way they decided to alter that strategy....

I saw this press release from Stony Brook today:

Top Minds In ‘Hobbit’ Debate Gather At Stony Brook University For 7th Annual Human Evolution Symposium

STONY BROOK, N.Y., February 6, 2009 – As the debate rages on about whether Homo floresiensis – so called “Hobbit” – fossils discovered on the Indonesian island of Flores in 2003 represent a separate human species, researchers currently in the process of describing and analyzing the remains will all be in the same place at once to advance the discussion on Tuesday, April 21, during the 7th Annual Human Evolution Symposium at Stony Brook University. Convened by Richard Leakey, the world renowned paleoanthropologist who is a Professor of Anthropology at Stony Brook University, the public symposium, “Hobbits in the Haystack: Homo floresiensis and Human Evolution,” is hosted by the Turkana Basin Institute at Stony Brook.

Nothing against having a meeting, which sounds like it would be very interesting to attend, but I notice that all the "top minds" seem to be of, well, one mind:

Among the researchers presenting are Michael J. Morwood from the University of Wollongong, Australia; Thomas Sutikna from the National Research and Development Center for Archaeology in Jakarta; Mark Moore, University of New England, Australia; Dean Falk, Florida State University; Peter Brown, University of New England, Australia; Matthew Tocheri, of the Smithsonian Institution; Susan Larson, Stony Brook University; William Jungers, Stony Brook University; and, Charles Hildebolt, Washington University in St. Louis.

I guess it's more of a mind meld. Or melt.

Er, that's probably just the warm Wisconsin weather talking... Anyway, I guess attendees who might be drawn by the idea that a "debate" is going to happen ought to know that any debating will be pretty minimal.

Jungers and colleagues (in press) provide a medium-length description of the lower limb remains from Liang Bua cave. In a second paper with much overlap of authors, Susan Larson and colleagues (in press) describe the upper limb remains. Both papers present quite a bit more information about the hindlimb remains than the earlier presentations of the postcranial remains in Nature by Brown et al. (2004) and Morwood et al. (2005).

I'm sitting down in front of the TV to live-blog the Nova episode on the Flores fossils, "Alien from Earth." It has the typical Nova high production values. We'll see what they show:

7:02: Opening montage has a little bit of everyone. Focuses on controversy. Has a great shot of a crowd of people in Liang Bua Cave.

7:03: "Flores is home to an ancient legend -- an elf-like creature with big feet and a voracious appetite...as mythical as leprechauns, elves, and hobbits...Were the storytellers of Flores inventing, or reporting?"

7:04: 1990's excavations on Flores turn up artifacts. Too old to be modern humans. Chris Stringer appears; describes himself as a skeptic to begin with. This is Morwood's entry: the tools are 700,000 years old; that begins his association with Flores. The program explains Wallace's line, talks about the Komodo dragon. Who made the mysterious stone tools?

7:06: Many shots of Liang Bua -- means "cold cave". Morwood interviewed in cave, many shots of the excavations, including people digging in very deep square pits. Roberts describes the problems with shoring up the sandy deposits.

7:08: Find a single bone, small. Another year yields little else other than a single tooth. Ultimately, they discover the LB 1 skeleton; the narration emphasizes how small the skeleton is -- there is no description here of the analytical process; no Peter Brown, etc. The "new species" status is being described as completely obvious from the point of excavation.

7:10: Now, Peter Brown. The lower jaw is "outside the range of modern human variation". The brain is tiny -- "smaller than a chimpanzee's." Brown "measured it and remeasured it" -- he was "flabbergasted."

7:11: Stringer: "If it is what it seems to be, it's an extremely primitive human-like form...living in a place where we never knew that humans had got to, altogether a challenging find."

7:12: Date of less than 30,000 years -- Roberts -- film goes to Chris Turney for radiocarbon dating. 18,000 years. I like the way the film is presenting the tremendous excitement of the new find -- everyone is describing their initial reactions upon getting the findings. Turney is probably the best at this.

7:14: Thumbnail version of human evolution, from australopithecus to us.

7:15: Ralph Holloway appears, playing his trumpet. Very, very cool. I mean, he's playing his trumpet in the middle of his lab, with skulls all around him. Man, I wish I were that cool!

7:16: Henry Gee. "Fossils....deal with it!"

7:17: "Just as the team were grappling with these details, the fossils were taken away." The narration describes Teuku Jacob -- "No one could refuse his request." Henry Gee -- "It's quite unethical...people should be given as much time as it takes" to analyze their fossils.

7:18: Stringer -- what is human? Bipedal? Tool using? Large brained? Now Maciej Henneberg enters: "Probably disease" -- Alan Thorne: "Pathology." Film goes to Paris -- a 3-foot dwarf who was a "court jester." Now, to St. Louis; Dean Falk and Hildebolt are studying CT scans of mircocephalics, Falk: "The CAT scans show that microcephalics and the hobbit are totally different." Cerebellum, frontal lobe differences. The film clearly illustrates them; this is a nice segment. They have shots of microcephalics. Falk is very convincing in this part; the graphics work well.

7:21: Bill Jungers -- "There are some bumps and bruises...there is nothing about the skeleton that suggests this was a sick hobbit."

7:22: James Phillips talks about the difficulties of tool manufacture. Could the hobbit make those tools? "A 400-cc brain, in my opinion, is not going to be able to produce a tradition with flake and blade technology."

7:23: Mark Moore and Jatmiko are in Indonesia, making experimental stone tools on a gravel bar. Good illustration of flake production. Notice that he's soft-selling the difficulty of this; he's using a leather pad to help him, he's collecting small flakes on a cloth, he's making the opposite case, really. Now, the film describes Moore's real point, which is that the Liang Bua tools are not very different from Oldowan tools in Africa.

7:24: Back to Falk. she's measuring brains; points to area 10 convolutions. Narration: the convolutions "expand a part of the brain vital for higher thinking and planning ahead." Now, the film is describing the elephant hunting. This is really going off the deep end here. But some scientists are "leery" of diagnosing a new species on the basis of one individual.

7:26: "DNA would settle whether the hobbit was a diseased human or a new species." Now goes to Shara Bailey, who's looking at the teeth. "It became very complicated." She's looking at LB 1 and LB 2 -- the premolars: "Teeth used for grasping." The premolars are the same, they were "strikingly similar." This is overselling. Bailey appears with Tim Bromage -- he points out that the tooth sizes are humanlike; "they have been shortened to accommodate the human-sized jaw...there is no pathology that shortens every element of the jaw..."

7:29: Tocheri playing the piano. His passion is music. This is starting to look like an advertisement for a career in jazz anthropology. The wrist bones, THE WRIST BONES. My goodness, the film is giving us hand skeletal nightmares. Much flashing like strobe lights. If this were a Japanese cartoon version, I'd be having seizures. Tocheri describes the hand anatomy, and there is some illustration with some animated hand bones. This could be done much better. The endocasts were clear, but these are not. Dart-throwing is an example of a "complex task" that chimpanzees can't do? Ah, now Tocheri is looking at the bone on his computer. This would be a lot better if they'd let him just show the anatomy.

7:32: Thorne: "If there is a developmental problem, then you would expect the hand and wrist bones to be any shape, but bizarre." Tocheri disagrees -- the wrist bones are their adult shape at 10 weeks of gestation. Jungers is "also convinced." "The evidence is pretty persuasive that this is a new species." Tocheri: "Science doesn't deal in persuasion, it deals in evidence. And now we have the evidence in front of us."

7:34: Where did the hobbits come from? They have film of the conference at Liang Bua. They're looking at the cave. "It threatens to overturn our understanding of where we come from."

7:35: Now, a split screen showing fossils and bones. "Large gaps remain in the fossil record." Henry Gee -- "We still know relatively little about the evolution of humanity." Gee thanks, Henry! I appreciate that one; we'll be answering the creationists there. "One fossil is enough to blow apart your entrenched idea of the linear process of evolution." Wow, there's no end of these nuggets of wisdom from Gee. Can we please talk to anthropologists here?

7:36: Morwood talks about critics' "preconceived ideas" that are threatened by the hobbits. Stringer: "In arriving at this creature, what was the ancestor?" Stringer is really good in this; he's giving all the transitions.

7:37: Leiden University; John de Vos and Robin Dennell have come to look at Pithecanthropus. This is a really large cast in this film. Very cool. Narration: "Could Homo erectus, tall and long-legged, evolve into a pint-sized version of itself?" Introduces island rule. Whoops, this is not a clear explanation. Why did rats grow again? Why did elephants shrink? Roberts says "no big predators." But what about those big Komodo dragons? This is a rotten explanation. Dennell is skeptical that the island rule could shrink a hominid. Jungers also "sees no evidence of a shrunken Java man." "I'm less and less persuaded that this could have evolved from Homo erectus."

7:41: The film shows us Lucy. Australopithecus is a possible ancestor of the hobbits. Bill Jungers compares Lucy and LB 1. "I was shocked and amazed by how similar Lucy is to LB 1." I don't see why he was shocked and amazed -- as you'll remember, I posted that observation here the day of the initial Homo floresiensis report! Roberts: "more and more like an australopithecine escaped from Africa." Dennell: "a hidden Asian lineage of hominins, only recorded in Flores at the very end of its trajectory." The film illustrates the Serengeti migrations of wildebeest, suggesting that hominids crossed Asian savannas as well, moving "widely outside of Africa."

7:44: Are there australopithecine remains outside of Africa? Dmanisi. Begins with film of the medieval church. Lordkipanidze is walking down into the excavation. Narration: "Five unique skulls from what appears to be a colony of ancient hominids." Brain capacities are small, 600 cc. Modern humans have more than 1500 (that's a little big, there). Could the hobbits de descended from hobbits. Lordkipanidze says possibly. Stringer appears, to say possibly. Dennell: "Fossil evidence from more than a million years ago in Asia could cover this (small) table. More than two million years ago, who knows what was living in Asia?"

7:48: Gee: "You find the most unexpected things in the most unexpected places."

7:49: Now, Elisabeth Daynes is sculpting the hobbit based on forensic techniques. It's a nice piece of work.

7:50: Gee: "World is full of undiscovered hominids, and I wouldn't be at all surprised if someone sent a paper to Nature, saying they'd found one alive in Sumatra or Borneo or wherever. I'd be very excited, but I wouldn't be a bit surprised." Gee to Bigfoot researchers: please send papers to Nature.

7:51: More scenes of the dig site, Morwood has discovered other promising sites, split screen with bones, etc. Man, Stringer's cast of LB 1 is miserable. He gets the last word. Good quote from Stringer, but a little abrupt, at the end.

Last words: I really liked the film -- it's visually compelling; it shows the cave and excavations; it shows museum collections in a very good light. It would be a good film to show classes. I think that the critics were given a say, and they were shown to be serious scientists. On the whole, the "circus" aspect of the Flores story did not appear in the film; it appeared as a serious scientific controversy.

Criticisms:

1. I think the narration did a disservice to Jacob, who after all isn't alive to defend himself. The film really glossed over the case for pathology. Given that the film was only 50 minutes, I can see the rationale for spending time on other things. However, this aspect reduced basically to "it's a microcephalic, it's not a microcephalic." That really doesn't describe the science; it's an oversimplification.

2. The part about tool manufacture and elephant hunting was silly -- I'm sure that the experts on the issue (Phillips, Roberts, Moore) gave quotes that would have worked to show the reasons for skepticism and responses. The film was edited in a way that really didn't give this problem any weight -- it was basically Phillips saying "they couldn't make tools," and Moore talking about the complexity of elephant hunting, and these tools aren't so hard to make, as he's showing us a knapping technique that nobody in the audience could do. I'm not coming down on either side; I'm just saying the film didn't present the problems well.

3. Where was Peter Brown? Where was Ralph Holloway? I mean, really? These are major players in this problem, they were filmed, and they were edited out of all but a few seconds. I don't want to criticize the film for showing too many people -- in fact, I really like the way they showed a broad range of scientists. Dean Falk got the right amount of time, and Shara Bailey was a good addition. But even Morwood could have had more time -- why can't we hear about his new sites from his mouth, for instance? I thought Chris Stringer did a good job giving context and transitions, but I wonder if that time might have been better given to someone more directly involved. Ditto with Gee -- why the heck is a science journal editor making himself part of this story?

4. Why all this emphasis on australopithecine origins? I mean, it's an interesting angle, but there's no evidence here at all. Could we have an analysis before we spend 10-15 minutes of the film on it? I appreciated seeing Lordkipanidze, and I liked what Dennell had to say, but it seems very premature. The film discards the Island Rule without any logic at all. To me, this is a real problem: the key question with the hobbits, is what do they tell us about the evolutionary potential of humans? If we discard the idea that they could have dwarfed on an island, then we're just begging the question.

OK, so those are my criticisms. Otherwise I really like the film. I'd like to have a copy to show in class. It's well put together, and it gives a good impression of how paleoanthropology is done. And it shows the experts to be people, not just talking faces.

The part with the endocasts was nicely illustrated. I credit Falk and Hildebolt for that, they've clearly spent a lot of effort finding the best ways to illustrate their points. I wish the film had done as well with the wrists, and for that matter with other elements -- how about those premolars the film spends 3 minutes discussing? And there are some loose ends that could be followed up in another film. For instance, what about those 700,000 year old tools? How did the hobbits get to this island? What about the stegodons -- nobody has ever straightened out whether they were always dwarfed on Flores. The Nova team almost certainly has enough film for another episode; I'd like to see them put some of it online.

On November 11, NOVA will present a new hour-long documentary on the hobbits, briefly described at the PBS website:

NOVA presents exclusive coverage of new excavations that experts undertook in the summer of 2007 at the site of Ling Bua on the island of Flores, Indonesia. These are the first investigations of the cave site since the sensational discovery of tiny and mysterious human fossil bones at the site in 2004. NOVA will investigate the furious scientific debate that continues to rage on what these "hobbit" bones represent. Are they fossils of a previously unknown primitive branch of the human family? Or are they remains of a dwarf race of modern humans suffering from a strange pathological condition?

The website associated with the show will launch November 7.

Homo floresiensis describer Peter Brown has kindly sent me a link to his own website, where he lays out evidence against the claims for recent dental work on the LB1 specimen:

The left first mandibular molar of LB1, Homo floresiensis, is heavily worn. Most of the enamel has been removed from the occlusal surface. The remaining enamel forms a ridge on the buccal and lingual margins, and there is a thin platform of remaining enamel in the disto-lingual quadrant. The softer dentine is somewhat scooped out and has a flat white appearance. There is some adhering sediment on the occlusal surface. Absolutely no evidence of any dental work, temporary filling or anything else. The tooth wear and oral health of LB1 are in all respects typical of older palaeolithic and hunter/gatherer humans, and living apes, and distinct from the mesolithic and more recent human burials in the Holocene layers at Liang Bua.

Brown's discussion includes high resolution photos of the specimen, the 3-D CT reconstruction featured in the Scientific American web story, and CT slices taken through the middle of the left and right teeth. I didn't think the 3-D CT slice was quite right to establish that the tooth was normally worn without question, since it cut through the buccal cusps which are unaltered in any event, but it does show a pulp cavity of normal dimensions for that area.

The slice taken through the centers of the left teeth, although a bit fuzzy (again, characteristic of the CT resolution), is much less equivocal: it shows a normal pulp cavity of equivalent dimensions to the right side and no evidence of alteration or drilling.

That's enough to convince me.

The rest of Brown's description serves to support his experience in examining archaeological teeth, including some photos of worn teeth of various stages. Some of this description will be interesting to readers who may not be as familiar with dental remains (or for that matter to dentists who aren't that familiar with archaeological samples of teeth). I think that these comparisons are sufficient to show that the particular pattern of wear and breakage on the LB1 lower left M1 is a bit odd compared to normal wear. But given that the visible material is in fact dentine (a fact established by the CT), there's nothing else that is outside the scope of either premortem or postdepositional processes. Any single specimen is likely to have idiosyncrasies, and by now it is abundantly obvious that LB1 is no exception to this rule.

UPDATE (2008/04/23): Elizabeth Culotta has a nice story about the tooth online at ScienceNOW.

In a New Scientist story about the feet of H. floresiensis:

"It puts another nail in the coffin of the disease hypothesis," says Henry McHenry, an anthropologist at the University of California, Davis who saw the presentation.

It's enough to drive me crazy. The rumor is that LB 1, the near-complete skeleton that serves as the type specimen of Homo floresiensis, may have evidence of dental work on its lower left first molar. Kate Wong wrote about it on the Scientific American blog, and Maciej Henneberg put some of the story in his new book about the Homo floresiensis saga. This means it's not just a rumor anymore: it's news.

So, does the claim have any merit? That's the part that drives me crazy. So much of this whole thing has been framed like a court of inquiry, with lawyer-like arguments about the published record. That's not how science is supposed to work.

For any other skeleton in the world, this claim would be extraordinarily simple and easy to test -- just look at the specimen, scrape at the supposed filling with a dental pick, and see what it is made of: dentin or dental cement? Or, look at a lateral radiograph.

Unfortunately, requests for access to the specimen to test the hypothesis have been denied. And no decent radiograph has emerged. In Kate Wong's article, Peter Brown has provided a CT image with a section of the left lower dentition. But the section appears insufficient to answer the question -- it has rather poor resolution (typical of medical CT scans), and cuts through the lingual cusps of the lower M1, not the buccal (cheek) cusps which appear to have been most affected by the irregularity.

I saw Maciej's pictures of the specimen and listened carefully to his line of reasoning. To be very clear, my opinion has very little value on this question: I've seen a lot of teeth, but I'm no dental anthropologist. At least one dental anthropologist I spoke to thought that the specimen was a fairly unproblematic broken tooth. Others have said it was consistent with drilling. Everybody I've talked to thinks that ultimately the question can only be settled with radiographs or direct observations.

So, I review the logic mainly to express why I would not dismiss the hypothesis of a filling in that tooth without further evidence. There are three elements:

1. The buccal enamel wall has an unusual, straight-edge discontinuity on the crown, and is raised by ca. 1.5-2 mm above the center of the tooth. The mesial enamel wall is broken away, and a whitish, flat, pitted surface characterizes most of the occlusal face, except for the enamel walls and the disto-lingual corner. This contrasts with the wear pattern on the antimere right lower M1, which has normal dentin exposure at the cusps, and the whitish color contasts with the dentin exposure of the other teeth -- although color may have no value given the uncertainty of photographs and the application of a chemical preservative to the specimen.

2. The lower molars are asymmetrically worn, with much more wear on the lower right teeth than the lower left ones. This would appear consistent with the individual chewing much more heavily on the right side than the left for some time prior to death.

3. The alveoli around many of the molars appear eroded, and a small caries appears on the left upper M1, in the region occluding with the lower left M1. The lower left P4 is absent postmortem, and its alveolus also appears eroded. These observations would all be consistent with spreading periodontal disease resulting from an initial large caries in the lower left M1.

Henneberg relays that his colleague Etty Indriati has looked into government records concerning the dental practices on Flores and other rural parts of Indonesia. According to Maciej, the government recommended a certain dental cement rather than amalgam fillings -- even though the cement does not last forever, it was much cheaper than preparing more permanent fillings and took less time to prepare. This cement does not contain metal like amalgam fillings, and might therefore escape detection in a superficial examination.

The CT image appears to show a normal-looking pulp cavity (or at least one with high contrast with surrounding material) in the lingual part of the tooth. That weighs against the idea of an extensive filling, but more detail in that region would be helpful. What is essential is to get a better assessment of the remains themselves.

I try to approach all of this stuff skeptically. The tooth is unusual, but there are ways that it might break naturally in the observed pattern. A premortem break or periodontal disease might cause asymmetrical wear by themselves. Preservative has been applied to the tooth's surface, making photographs misleading. And several skilled osteologists (including one dentist) examined the remains without noticing anything strange enough to scrape the tooth with a dental pick.

All those things weigh against the hypothesis that this tooth has had dental work. And yet, there is something unusual about it, and this hypothesis should be absolutely trivial to test. The CT scan may be enough, although with its resolution I would guess that a radiograph may be more convincing. A simple look at the specimen would be enough. Or a direct radiocarbon date -- which despite the sampling of collagen for DNA testing, was never performed.

So, I would like to see the radiograph.

Lee Berger, Steve Churchill, Bonita De Klerk, and Rhonda L. Quinn have written a paper in PLoS ONE describing the skeletal remains of small-bodied humans recovered from two caves in the Rock Islands of Palau.

Full disclosure: I was the academic editor for this paper at PLoS.

OK, editor, what did you do for the paper?

The editor's role is to evaluate the manuscript's suitability for publication -- does it conform to the journal guidelines? Is it scientifically valid? Does it cite the existing literature appropriately? Do the observations support the claims made? A few manuscripts may be rejected immediately, because they fail to meet basic criteria of scientific value or readability.

Most manuscripts require the editor to seek out the opinions of additional experts in the process of peer review. PLoS ONE, unlike most journals, is committed to openness in the review and publication process (journal information).

In the case of this manuscript, I think it was a good fit to PLoS ONE because of the potential to report the new finds in an open access forum, where anyone can read the original research. It is not a monograph on the archaeology or skeletal biology of the sites, it is merely a preliminary report. However, unlike the kind of preliminary reports that we often see in journals like Nature or Science, in this case the journal provided more space for description and the potential to provide long lists of specimens. Many of those additional details were added to the manuscript in response to my editorial comments. If you read the reviewer reports for the paper (available at PLoS ONE), you can see that these additional details were essential to the scientific value of the manuscript, and that is why I required them. In addition, I suggested many other changes that would increase the value of the manuscript. The final version reflects the authors' responses to these changes: a preliminary report on the skeletal remains, in context, given the limitations presented by preservation and the need to conserve and prepare additional specimens.

Rex Dalton made the National Geographic Society's involvement with the research into a news story. Do you have any involvement with the media for a story?

Nothing at all. Sadly, most good manuscripts don't get any media attention.

Dalton emphasized the media attention to the find, particularly focusing on the role of the National Geographic Society. NGS produced a documentary about Berger's work on Palau (he is an NGS grantee).

In this case, National Geographic funded the work and apparently produced a documentary about it. Their production wasn't disclosed to the journal, and I view it as irrelevant to the scientific evaluation of the manuscript.

Paleoanthropologist Tim White is quoted in Dalton's story, saying that it appears that the "review process [was] driven by popular media." Since White was not involved in the review process of this paper, he obviously is just speculating.

I tend to give him the benefit of the doubt, since in this story it appears that Dalton was trying to play up any contrary quotes about the findings. Why else would he run otherwise-uninformed comments of the kind in the story?

I would tend instead to ask these questions: Does the Nature Publishing Group (NPG), in publishing Rex Dalton's piece, have a vested interest in the credibility of their own journals, in comparison to open access outlets like PLoS? Do NPG journals regularly receive manuscripts and publish them based on the associated media attention? Do they have an interest in pressuring grant agencies, like the NGS, into encouraging submission of manuscripts to NPG journals instead of alternate outlets? Does NPG have a well-established record of running stories questioning the value of open access publications?

In other words, consider the sources.

But aren't there other, normal-sized people on Palau at the same time?

In Elizabeth Culotta's article about the Palau specimens, she quotes archaeologist Scott Fitzpatrick:

But archaeologist Scott Fitzpatrick of North Carolina State University in Raleigh, who has worked in Palau for a decade, says he doesn't think the bone beds represent a true population. In a site only 4 kilometers from Berger's caves, he has excavated the burials of Palauans of similar age--and normal stature. That would seem to rule out isolation and island dwarfing, he says. "It would be very unusual to have a group of people living in close contact with a normal size population who evolved to be smaller." Instead, "the most parsimonious explanation is that they were Palauans with a genetic anomaly leading to small people who were buried in a clan or family plot."

Fitzpatrick has been excavating on Palau for a long time -- in comparison, Berger is a real Johnny-come-lately, who happened across his sites while on a vacation. So it's fair to say Fitzpatrick knows what he is talking about -- he has documented the earliest radiocarbon-dated cemetery on Palau, dating to approximately 3000 years ago.

The osteology of the skeletal remains from that cemetery, Chelochol ra Orrak, were reported by Fitzpatrick along with Greg Nelson, in 2006. That preliminary report is similar in form to this one, and they report measurements of the specimens. There are fewer specimens in that cemetery than are reported by Berger et al. from their caves, but the reported measurements are very comparable.

For example, Nelson and Fitzpatrick (2006:5) report a single femur complete enough to assess length; it has a maximum length of 392 mm and a maximum head diameter of 38.5 mm. This is smaller than the maximum femur length for the Khoisan sample reported by McHenry (1991), with an average length of 405.1 mm (S.D. 20.86), but longer than his (2) Akka Pygmy specimens (330 mm, S.D. 5.66). Berger and colleagues have no femora sufficiently preserved to estimate length, but their two femoral heads have diameters of 38.8 and 36.1 mm. These compare to Andamanese mean values of 37.3 mm and a San mean of 42.3 mm; McHenry's Khoisan sample has a mean of 37 mm.

Berger et al. report the proximal mediolateral diameter of two tibiae (63.1 and 53.1 mm); Nelson and Fitzpatrick (2006) report one specimen with a epiphyseal breadth of 64.8 mm and an estimated maximum length of 318 mm; the paired tibia has a length of 315 mm. By comparison, Flower (1885) reported a mean tibia length for Andamanese females of 321 mm.

In other words, the comparable remains published by Nelson and Fitzpatrick (2006) and Berger et al. (2008) appear to be consistent in size, and all within the range for small-bodied and pygmy human populations. One caveat is that the crania are as yet not directly comparable: Berger et al. cannot assess the crania from their caves because they remain to be prepared. Nelson and Fitzpatrick (2006) report two adult crania, the more complete of which (presumably male) is not a small skull, averaging larger in all preserved dimensions than Andamanese. Berger et al. (2008) report larger skeletal remains from areas that they believe are later in the chronology.

In any event, we don't need to posit two distinct populations living side-by-side to explain these remains. Working out the actual dynamics of this population over time is going to require a detailed understanding of several complicated stratigraphies, as well as detailed comparison of the skeletal remains. Whether they do in fact represent a single population must be determined by comparing the bones from these different sites with each other in a longer treatment. I hope that the analysts can get together to assess the sample as a whole.

Is this an extreme case of island dwarfing?

There's no question that the bones are small. However, I would not characterize them as extremely small compared to other small-bodied human populations. The paper provides a series of comparisons of linear dimensions of the Palauan remains to other small-bodied skeletal samples, including San, Onge, and Great Andamanese. In most cases, the Palauan remains average slightly smaller than these small-bodied samples, but within one standard deviation of the mean. A few adult specimens are substantially smaller, but it is not obvious that they are outside the range of living pygmy populations.

I should mention that is also true for the Liang Bua skeletal remains from Flores -- they are not obviously outside the range of living pygmy human populations -- despite the fact that none of the publications have reported comparisons with pygmy populations.

So, this would seem to be within the ordinary range of dwarfing in human pygmy populations. That raises the possibility the people may have been derived from such a pygmy population -- for instance, by colonization from the Philippines where small-bodied populations such as the Aeta and Batak are found today. There may be nothing exceptional about a relatively long-distance colonization of Palau by these peoples, who must after all have gotten to the Philippines!

I would say that the initial dispersal of the many small-bodied populations of mainland and island Southeast Asia is shaping up to be a very interesting anthropological topic. This population history has been partly obscured by the subsequent expansions of agriculturalists -- indeed, new colonizations like that of Palau may represent the effects of such interactions. Only traces of the ancient diversity remain, so it is difficult to reconstruct the ancestral population structure. But it is becoming increasingly clear that this was a cosmopolitan population, inhabiting several outlying island groups as well as areas of mainland Southeast Asia and the Sunda shelf.

In that context, small body size must be explained not merely as a consequence of inhabiting small islands, but more generally as an adaptive strategy for hunter-gatherers living in tropical ecologies. That is also true in the African context, so it should come as no surprise.

What do these small-bodied skeletons tell us about Homo floresiensis?

These ancient skeletons from Palau are not anything other than small-bodied modern humans. There is no question about that.

However, the bones share some interesting features with the Flores specimens. Here is what the authors say about the resemblances:

We feel that the most parsimonious, and most reasonable, interpretation of the human fossil assemblage from Palau is that they derive from a small-bodied population of H. sapiens (representing either rapid insular dwarfism or a small-bodied colonizing population), and that the primitive traits they express reflect possible pleiotropic or epigenetic correlates of developmental programs for small body size. In the comparisons drawn below, we note the shared possession of these traits with the Liang Bua fossils not to imply phylogenetic affinity or taxonomic identity, but rather to caution that some of the primitive features argued to reflect an ancestor-descendant relationship between H. erectus and H. floresiensis may also be homoplastically shared with modern humans from Palau, and thus that care must be exercised in interpreting their taxonomic and phylogenetic significance.

Also:

These results also suggest that the simple presence of additional small-bodied specimens with reduced chins (that cannot be shown to share all of the traits considered taxonomically significant in the Holotype Flores LB1) is insufficient to confirm the taxonomic validity of H. floresiensis.

I think that's pretty much the extent of what the Palau skeletal remains can say about the Flores sample. This is a reminder that the best comparative material is relatively local -- they should be compared to regionally similar populations, and populations of similar body size, rather than random people from European museum collections.

I think they also provide a cautionary note to the kind of trait-based typological classification that has been applied to the Flores specimens. Just because a sample lacks so-called "derived" features of "anatomically modern" populations, does not make it a member of a pre-human hominid population. "Anatomically modern" is itself a typological classification. Living people are variable and many express morphological features shared with fossil humans of various ages.

To be sure, the Flores LB1 specimen presents a large number of features that would be unusual in a living person, and the hypothesis that it represents a distinct human species is well-supported on this basis. On the other hand, it also has some features that are derived in recent human populations and others that are relatively common in small-bodied human populations in the region.

Nevertheless, the Palau remains do not provide any positive support to the idea that the Flores LB1 specimen is a microcephalic modern human. In particular, like other small-bodied human populations, none of the Palau skeletal remains indicate anything like the reduced brain size of LB1. There is nothing in this research concerning wrist morphology, humeral torsion, rotated premolars, or any of the rest of the odd features of LB1, nor is there any assessment of the paleopathology of the remains.

References:

Berger LR, Churchill SE, De Klerk B, Quinn RL (2008) Small-Bodied Humans from Palau, Micronesia. PLoS ONE 3(3): e1780. doi:10.1371/journal.pone.0001780

Nelson GC, Fitzpatrick SM. 2006. Preliminary investigations of the Chelechol ra Orrak Cemetery, Republic of Palau: I, skeletal biology and paleopathology. Anthropol Sci 114:1-12.

Flower WH. 1885. Additional observations on the osteology of the natives of the Andaman Islands. J Roy Anthropol Inst G Br Irel 14:115-120.

I'm just doing some background reading about the body size of pygmies (for both obvious and not-so-obvious reasons) and I thought it worth making a note of this quote, from last year's paper by Andrea Migliano, Lucio Vinicius, and Marta Lahr:

Finally, the data presented here show that pygmy body size evolved through earlier cessation of growth, being therefore the result of changes in late rather than early stages of growth. This explains why brain growth, which is completed years before the onset of adolescence (28), is not affected in human pygmies (29). Therefore, if Homo floresiensis is a dwarfed form of Homo erectus, as proposed in ref. 29, the evolution of small body size on Flores could be understood as the life history consequence of ecological conditions in islands, such as increased extrinsic mortality rate and reduced resource availability (30); however, its small brain size and low encephalisation require the postulation of different adaptive mechanisms affecting earlier stages of development.

That's the concluding paragraph of what is a very nicely-done study of mortality and fertility in pygmy populations. It came out the during the acceleration press flurry in December, so I wasn't able to write it up at the time. It's certainly worth doing so, though.

The paper proposes that pygmy human populations are small because of a life history tradeoff. A "tradeoff" is the idea that a phenotypic change in either direction may have advantages and disadvantages, and selection may arrive at different optima in different populations.

In the case of life history and body size, both growing longer (and larger) and maturing faster (and smaller) have possible payoffs. Growing longer may have a fertility payoff, as larger size facilitates larger infants and shorter birth intervals. But maturing faster has a direct payoff of shortening the generation length -- all other things equal, an individual improves her fitness by reproducing younger.

So either younger or older maturation may enhance fitness, in some circumstances. Which will work in any given population depends on other factors -- in particular, the mortality pattern. If individuals have a high risk of death in early adulthood, delaying reproduction will be a bad strategy. In short, individuals should reproduce at 16 (or earlier) if there is a fair chance they will be dead by 25 or 30.

Naturally, everyone would rather live longer. But assuming that people can't control when they die, the only way to insure their fitness is to reproduce earlier.

This hypothesis, presented by Migliano et al., is about the proximate mechanism of evolution. The authors seem content to rely on traditional hypotheses about locomotion, nutrition, and thermoregulation to explain the ultimate causes of small body size -- "ultimate" in the sense that these may be the environmental causes of high mortality:

If our hypothesis is correct, the causes of the extremely high mortality rates among human pygmies need to be explained. It is here that the traditional hypotheses explaining the small body size of pygmies may prove useful. Although the challenges posed by thermoregulation, locomotion in dense forests, exposure to tropical diseases, and poor nutrition do not account for the characteristics of all pygmy populations, as pointed out by Diamond (5), they may jointly or partially contribute to the similarly high mortality rates in unrelated pygmy populations. We argue that the small body size of African and Asian pygmy populations evolved independently as a case of evolutionary convergence, resulting from a life history tradeoff between the fertility benefits of larger body size and the costs of late growth cessation under the circumstance of significant young and adult mortality.

The demographic data presented in the paper are sobering -- particularly the low survivorship values for pygmy populations across late childhood and early adulthood. However, I wonder how much of the early adult mortality in the pygmy demographic data is attributable to new pathogens. These are certainly important today, but they would not have been during most the time that small body size was being selected in these groups. On the other hand, ancient endemic pathogens and parasites also may contribute to those mortality numbers, and these might well have occurred at higher intensities in forest peoples across their histories.

References:

De Souza R. 2006. Body size and growth: The significance of chronic malnutrition among the Casiguran Agta. Ann Hum Biol 33:604-619. doi:10.1080/03014460601062759

Migliano AB, Vinicius L, Lahr MM. 2007. Life history trade-offs explain the evolution of human pygmies. Proc Nat Acad Sci USA 104:20216-20219. doi:10.1073/pnas.0708024105

For those of you who may be wondering what is wrong with paleoanthropology that we can't just resolve the hobbit problem, I can only say one thing: We are not alone.

For instance, there is the idea that a "mammoth-killing" impact caused the Younger Dryas, suggested in a paper last year by R. B. Firestone and colleagues.

If you like the idea, this seems like a bad sign:

Archaeologist Vance Haynes, professor emeritus at the University of Arizona, Tucson, is finding likely looking magnetic spherules in the darnedest places. He has spent 30 years studying Clovis sites, many of which the Firestone group sampled. As a check on his own ongoing independent analysis of YD samples, he collected a modern sample. "I got 300 grams of dust off the roof [of my house], and it's full of magnetic microspherules," he says. Whether they are the melted, iridium-rich micrometeorites that continually drift down from the upper atmosphere or the product of high-temperature industrial processes such as coal burning, he doesn't yet know. Either way, they could be trouble. The cosmic dandruff of microspherules could have salted sediments forming 12,900 years ago with iridium, while the humanmade variety might have settled on modern outcrops before sampling.

That's from a long news article in Science by Richard Kerr, titled "Experts find no evidence for a mammoth-killer impact."

Like almost every other temperature fluctuation of the last 80,000 years, the Younger Dryas has been attributed with quasi-magical power: in this case, the power to kill mammoths and extinguish cultures. And hey, maybe it really did...but I have a lot of skepticism when associations are made on the basis of dating uncertainty. It would help if these climate changes would affect every species and culture, rather than showing catastrophic effects on particular ones without showing any signs of affecting others.

Of course, without the biological and cultural fallout, the story of a particular climate cycle isn't very interesting. Nobody would care. With the Younger Dryas, we have human archaeological evidence from all over the world 12,900 years ago. Surely something will match! Of course, the megafauna didn't become extinct precisely then, exactly. But no matter -- it's close enough. Surely these events would have been devastating for animals and plants, right? Most of them were lucky enough to escape the devastation with their lives, but a few unlucky victims because extinct, thousands of years afterward.

A meteor helps to spice it up, and in this case we have the whole package:

The catastrophe had taken place a geologic instant ago--closely coinciding with the disappearance of North America's mammoths and the continent's earliest human culture (Science, 1 June 2007, p. 1264). Then came the 26-author paper last October in the Proceedings of the National Academy of Sciences (PNAS), not to mention the hourlong National Geographic Channel documentary running on cable since last October, with more coverage on the way from the History Channel and PBS's prestigious program NOVA.

Uh, yep. Sounds familiar so far. Now is the time to bring out the spurned skeptics:

"The whole thing is contrived," says geochemist and impact specialist Christian Koeberl of the University of Vienna, Austria. "Their data don't agree with anything we know about impacts. It just doesn't make any sense. Occam's razor has been put safely in a drawer somewhere."

Kerr lists an impressive array of scientists who think the evidence for an impact doesn't add up. I don't have any particular opinion -- my main skepticism concerns the proposed link between climate change and Clovis, which is a separate issue from whether an impact occurred.

But the story is a good one to watch, and has many parallels to the Flores hobbit story, considering different standards of evidence, the interactions of specialists from different scientific specialties, and the use (or abuse) of the press.

P. S. A number of abstracts from the 2007 AGU meetings pick up the question.

References:

Firestone RB and lots of others. 2007. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proc Nat Acad Sci USA, 104:16016-16021. doi:10.1073/pnas.0706977104

Kerr RA. 2008. Experts find no evidence for a mammoth-killer impact. Science 319:1331-1332. doi:10.1126/science.319.5868.1331

It's all over the news this week: Australian researchers Peter Obendorf, Charles Oxnard, and Ben Kefford claim that the Homo floresiensis skeleton LB 1 belonged to an individiual suffering from congenital hypothyroidism, or cretinism. The disorder has a number of developmental and skeletal effects, including short stature, and they run through a list of LB 1's characters that appear to match the disorder.

Needless to say, others disagree. So here is my take:

Is LB 1 a cretin?

No.

The authors of this research provide a list of characters of the fossil that are consistent with the diagnosis of cretinism. Some of them are interesting, in that they have not previously been connected to any pathology. But the most important observation is simply wrong. With that falls the hypothesis.

Is the pituitary fossa of LB 1 large?

The diagnosis of cretinism would be most strongly supported by the authors' claim that LB 1 has a large pituitary fossa.

If you haven't learned this lesson yet, take note: If Ralph Holloway and Dean Falk agree on an anatomical observation, then it is correct.

The two have been interviewed in a number of the press articles. My favorite comes from Kate Wong, where both Holloway and Falk give long statements. These are really too long for me to block quote, so go read them. But I'll take one sentence from each:

Falk:

Now that we've reexamimined the CT images, we can tell
you that there is absolutely no way that the length of the pituitary fossa could be 12.9 mm.

Holloway:

...the pituitary fossa on my endocast is, to my mind, tiny, and I don't get much more than about 6 mm in dimensions, either [anterior-posteriorly] or in breadth, so I don't understand where they have data to make such a claim.

That's the end of this story.

How did the paper get that so wrong? I mean, didn't they just measure it?

They took the images of CT scans presented in the supplementary data to Falk and colleagues' 2005 paper on the LB1 endocast, blew them up, and attempted to measure the length of the pituitary that way. To understand where they went wrong, I did the same thing. Here's the picture, blown up:

Supplementary Figure 2e from Falk et al. 2005, focusing on LB1

An estimate of 12.9 mm is wrong on many levels. For one thing, how many significant digits do you think you could get out of that figure? The blown-up version is clearly very pixelated. That by itself might not be so bad -- after all, a medical CT begins with limited resolution anyway -- but in this case there is no clear way to identify the borders of the pituitary fossa. We might well do better with the endocast itself, or with the ability to rotate and relight the CT image, because we could explore the contours more thoroughly. Here all we have is a computerized rendering of the surface in which our recognition of the detail depends entirely on the simulated lighting.

This is where they went wrong. No replicable estimate is possible from that rendering, but they went with one anyway.

But everyone knows that you can never do any real research using photographs. You must examine the original specimens!

In my opinion, that would be exactly the wrong conclusion to draw from this case. The problem was not that they attempted a new measurement on a photograph; it was that this rendering is not a photo, and does not provide sufficient information for such a measurement.

In some cases, a well-resolved photograph can give better basis for a measurement or comparison. In almost all cases, a research article accompanied with original photos will allow experts to assess the accuracy of claims and replicate the observations. Making work as easily replicable as possible should be the goal of every good scientist.

It doesn't help to read things like this, from the Rex Dalton article in Nature:

[Peter] Brown is critical of the cretin theory. "I am the only person on the planet to have seen what's left of the pituitary fossa," he declares. "It is very poorly preserved and not capable of meaningful measurement."

It may be true, but that doesn't make it science. If nobody can see it, then nobody can replicate it. Which means we have no reason to believe it.

Happily, in this case independent experts have access to the scans and can tell us what they look like. On the other hand, if I were sitting on scans like these, with people publishing critical articles every couple of months, you can bet I would put them on an FTP site and let everybody have them. Three quarters of the problems would immediately vanish, because people could refute their own hypotheses before they went anywhere, and reviewers could work from the best information also.

The remaining quarter of the problems would at least be interesting!

Oh, now that can't be the most boorish of the comments in the press. I mean, after all, this is the hobbit!

Well, let's see....from The Australian:

The [cretinism] notion's been ignored for good reason, said evolutionary anatomist and paleoanthropologist William Jungers of Stony Brook University in New York state.

"The cretin and hobbit (body types) exhibit virtually no similarities except for short stature. That is, they're both short. End of story," said Professor Jungers who has studied the hobbit remains first-hand.

"The only merit to this paper is their correct dismissal of a competing 'pathology du jour' called Laron Syndrome (which causes skeletal deformities). The rest is a rather large and stinky pile of misinformation and wild speculation," he claimed.

Or, this one, from the same article:

A final kick came from biological anthropologist Colin Groves of the Canberra's Australian National University: "I recall spending an hour or so in the pub with Peter Obendorf about three years ago when he confided to me about this latest bee in his bonnet."

"As fast as he produced supposed similarities I put stumbling blocks in his way. I warned him that he would simply be laughed to scorn if he produce what is mainly idle speculation," Professor Groves claimed.

Ha, ha, ha! Here's Groves again, in The Guardian:

"I regret to say that this paper cannot be regarded as a contribution to our understanding of the Flores hominin," said Prof Colin Groves, a bioanthropologist at the Australian National University, Canberra. "Many of the claims lack evidence (ie they are sheer speculation), some even fly in the face of the evidence. I am very sorry indeed to see serious scientists involved in such a travesty."

Then there's this piece of legal news:

"The Tolkien trustees do not file lawsuits lightly, and have tried unsuccessfully to resolve their claims out of court," Steven Maier, an attorney for the Tolkien estate based in Britain, said in a statement. "New Line has not paid the plaintiffs even one penny of its contractual share of gross receipts despite the billions of dollars of gross revenue generated by these wildly successful motion pictures."

Ooops....wrong hobbit....

Is there anything salvageable out of this?

Well, they wrap up a number of the skeletal features of LB 1 into their cretinism hypothesis. My personal opinion is that you have to start by explaining the brain size, and cretinism doesn't. None of their comparative sample of European cretin specimens has a brain size smaller than 1000 g. The paper claims that these would "scale with height" down to 700 g, but that is just a projection outside the data's range based on the regression.

Without an explanation for the brain size, and without any unique character to confirm the cretinism hypothesis (like the pituitary size), they have to resort to a list of the known problematic characters of LB 1, such as the Tomes root, the humeral torsion, the relatively large foot and broad diaphyseal breadths. But these match other pathological explanations as well -- most of them were cited in the Laron syndrome paper, for example.

To the extent that these features are "developmental abnormalities," they may be explained by any number of conditions. It's possible that they may have resulted from a unique evolutionary history, either as side effects of other adaptive changes in a small population, or as fixed deleterious variants.

The multivariate analysis of the skull measurements is not convincing. Of course, it is extraordinarily rare for me to find a multivariate comparison convincing about anything.

References:

Dalton R. 2008. Hobbit was 'a cretin.' Nature 452:12. doi:10.1038/news.2008.643

Culotta E. 2008. Were the Flores hobbits really cretins? ScienceNOW March 5, 2008. Full text

Obendorf PJ, Oxnard CE, Kefford BJ. 2008. Are the small human-like fossils found on Flores human endemic cretins? Proc Roy Soc Lond B (early) doi:10.1098/rspb.2007.1488a>

It's that time of year again -- the time when those boring ``Year in Review'' magazines are on newsstands, and when pundits make fools of themselves predicting what will happen in the next year.

Well, I'm not too proud to join the fools, as I've shown the last two years. In 2006, I got five predictions right out of ten. Not bad for my first outing, but you'll see that last year's predictions fared even better:

• 10. Sahelanthropus postcrania will be published. I'm frankly shocked that this didn't happen. I don't doubt the rumors, but I'm starting to wonder whether this story is more interesting than it looks....
• 9. Two words: Holocene evolution. OK, this was a little unfair, considering that my work was an important part of making this prediction come true. Still, Discover made ``recent human evolution'' one of its top 100 science stories of the year, even before our December paper came out -- mainly on the strength of the paper by Scott Williamson and colleagues from earlier this year. And "Human genetic variation" was Science's "Breakthrough of the Year" -- most of that variation representing recent evolution.
• 8. Despite (or because of) the success of the Neandertal genome project, there will be no genetics of any kind published on early modern skeletal material. Puzzling, isn't it? But then, considering the trouble with Neandertal contamination reported in August, maybe we're better off leaving the early Upper Paleolithic alone for a while.
• 7. The mitochondrial history of human dispersals will become more and more detailed, but no paper will test against other loci. D'oh! Reading this one a year later, it's pretty obvious that I should have included Y chromosome in this one, since those two get compared all the time! Proofread, Hawks!
• 6. Another (yes, another) paper about the chimpanzee-human divergence will peg it between 5 and 7 million years ago. Will they never tire of these? Hobolth et al. (2007, PLoS Genet 3:e7) pegged the divergence at 4.1 million years. That's too recent to fit my prediction. Instead, I have to turn to Ebersberger et al. (2007, Mol Biol Evol 24:2276), who placed the divergence at 5.7 million years ago. Both estimates are too recent for Sahelanthropus, which the geneticists have started to figure out....
• 5. Three papers with new Ethiopian fossils. The last few years, one annual Ethiopian find seemed to be predictable enough. So I figured, why not three? We got a not-nearly-noted-enough paper this summer by Gen Suwa and colleagues descringing the Konso Homo erectus remains. Then, Suwa brought us Chororapithecus -- hey, I didn't say "hominid!" That's two. But despite the long-ago announcement of the Woranso-Mille skeleton, its appearance in a meetings abstract and a mid-summer press release about further Mille fossils, all we got from the peer review system is a lousy faunal list. Well, the faunal list does include the hominids. Should it count as a "paper with new Ethiopian fossils?" I'll say yes -- hey, unlike Aramis, at least the Mille fossils are new!
• 4. Another early Upper Paleolithic specimen will emerge from a museum collection. The only bizarre thing about this one was the location: South Africa. Hoffmeyr may not be that convincing as a European early Upper Paleolithic skull, but it was sure sold that way. Weird.
• 3. A big year for Miocene apes, which will look increasingly important in the story of human brain evolution. No brains, but it sure was a big year for Miocene apes, with two significant East African discoveries claiming to push back the timeline of African ape divergence.
• 2. Maturation rate in early Homo becomes a dead issue, because of the variation in dental and skeletal maturation in living people. Wishful thinking. Still, did Tanya Smith (2007) breathe new life into perikymata? Let's just say that unresolved questions remain.
• 1. The year will end without a single new hominid species having been named. This one was like dodging a bullet, since new species riffle out of paleoanthropologists' minds all the time. From 2001 to 2006, there were six (six!). In 2007, none.
• BONUS: A dramatic development in the problem of pre-2.0-million-year-old Homo. Rats.

OK, that's seven out of ten. It's beyond belief that I did better in the top five than the bottom five -- I picked those because they were far out there. I mean, really -- a new Upper Paleolithic specimen from a museum collection? After Muierii, that's like calling lightning to strike twice. But there it is, and in January, no less.

I'm clearly going to have to pick stranger predictions this year. And I'll have to be careful about that "dramatic development" line -- I mean, it's appropriately Delphic, but what is it supposed to mean, really? I wonder whether "operatic development" might be better.

And do I dare call down my non-lightning strike for a third year? It's ruining my percentage! It's starting to reek of desperation -- I mean, it starts to look like the stopped watch effect even if it happens.

Oh, well. I mean, those are just the risks of predictions, right? Suppose in the preseason I had picked Kansas to win the Orange Bowl!

• 10. A dramatic development in the Sahelanthropus story.
• 9. Both major-party candidates for the 2008 U.S. Presidential election will accept evolution.
• 8. This year's featured piece of anatomy: the femur.
• 7. No new hobbits, at least, not from Flores.
• 6. An incisive example of introgression in East Asia.
• 5. A viral insertion in the human genome will tell us about a disease of the australopithecines.
• 4. Another language gene joins FoxP2. No word on whether Neandertals have the human version.
• 3. Homo habilis: an endangered species?
• 2. This year, something new from three A's: A. afarensis. A. africanus. Atapuerca.
• 1. Oh, and one more A. Ardipithecus.
• BONUS: A big, big year for Neandertals. I mean, besides the election.

There you have it. I'm not sure which of these is the riskiest, but I'm sure they're more out on a limb than last year!

Science's Michael Balter reviews the recent Cambridge conference on "Global Origins and Development of Seafaring". The article begins with a suggestion that the first inhabitants of Flores floated there on vegetation rafts by accident -- channel crossings being otherwise impossible for Lower Paleolithic hominids:

"Flores is the exception that proves the rule in terms of when seafaring really began," says Atholl Anderson, a prehistorian at the Australian National University (ANU) in Canberra. [Jon] Erlandson agrees: "Otherwise, H. erectus should have colonized Australia and the surrounding islands."

It mostly seems to be about Wallacea, Sahul, and Melanesia.

The article features a disagreement concerning the colonization of these regions. Some think that island colonizations started before seafaring technology was quite ready for prime time. In that scenario, the initial habitation of parts of Wallacea along with Australia and New Guinea was a sort of accidental chain of small founding events, possibly as early as 60,000 years ago or earlier.

The opposing viewpoint holds that these islands (and continent) were inhabited relatively late and quite suddenly, by people who had developed an advanced seafaring skill. Balter quotes University of Utah archaeologist Jim O'Connell to good effect:

In the last few years, O'Connell, together with archaeologist Jim Allen of La Trobe University in Bundoora, Australia, has argued from a detailed analysis of radiocarbon dates for a "short chronology" that puts the occupation of Sahul no earlier than about 50,000 years ago. He pointed out that by 45,000 years ago modern humans had colonized a number of islands between Sunda and Sahul, called the Wallacean Archipelago, which stretched at least 1000 kilometers even when sea levels were at their lowest. Reaching many of these islands required sea crossings of 30 to 70 kilometers, sometimes against the currents. Most animals from Asia never achieved these crossings, implying that humans must have used technology to do it. That 5000 years of colonization, O'Connell said, represented a relatively short "archaeological instant."

O'Connell also argues that some of the island sites before 40,000 years ago include deep-water fish, suggesting relatively advanced ocean-going boats at that time -- something I noted in a post on the East Timor site, Jerimalai.

Which side is right? I don't know, but it's good that they are formulating hypotheses this way, involving the technological trajectory, genetic constraints on small populations, and various ecological parameters.

References:

Balter M. 2007. In search of the world's most ancient mariners. Science 318:388-389. doi:10.1126/science.318.5849.388

Julien Riel-Salvatore figures the Liang Bua "hobbit" tools aren't so complicated after all:

Personally, I have never been especially convinced by the claims for systematic blade technology associated with LB1. The two 'macroblades' (a, b) and two 'microblades' (e, f) illustrated by Morwood et al. (2004: Fig. 5) aren't very regular (the central dorsal ridges are not straight in any of them) and none of their platforms (from what can be seen) are truly 'lipped', unlike the platforms usually generated by soft-hammer production (which is largely employed in true blade production). Furthermore, the illustrated "burin core" really looks to me like a flake core from which a series of small flakes with subparallel edges were knocked off, not a bladelet core. None of this really conforms to the "narrow blades removed sequentially from blade cores" alluded to by some detractors (in Culotta 2007:741) who considers they can only be produced by H. sapiens (a misleading assertion anyway [Bar-Yosef and Kuhn 1999]). Rather, M. Moore and T. Sutkina , who have studied the tools, argue that they represent fairly "simple stone artifacts" (in Culotta 2007:741), which happen to include a few flakes that are twice as long as they are wide - the traditional, if slightly outdated, definition of a blade.

Julien notes that archaeologists often illustrate the "best looking" tools in their papers, and the LB tools aren't all that good looking -- to his mind, they aren't convincing as intentional blades. He connects the idea of rudimentary tools to the wrist morphology, suggesting that the wrist may mean a lack of fine motor control.

As for myself, I agree it's hard to tell. I find Mark Moore's papers on the technology in SE Asia/Australasia to be informative, but it's not entirely clear which direction to interpret them. One consistent point (c.f. Brumm and Moore 2005, Camb Arch J 15:157) is that modern humans in the area did not create anything clearly more "Upper Paleolithic-like" than the LB tools. The abilities of local modern humans don't really address whether a "Homo floresiensis" population might have produced similar artifacts.

Nor is the anatomy of the wrist very convincing on the question of tool manufacture: Until we know about the wrist morphology of late Acheulean/early MSA people, we simply aren't going to know whether "complex" or "sophisticated" tools need any particular wrist architecture.

So, with the tools, I wonder whether people have been trying to connect dots that don't need connecting.

Meanwhile, Leigh Dayton of The Australian reports that the LB tools show "evidence of plant work and butchery":

Working with University of Queensland colleagues Michael Haslam and Gail Robertson, Dr [Carol] Lentfer found evidence of plant work and butchery on stone flakes and cobbles from archeological layers ranging from 12,000 to 55,000 years old.

They identified blood and bone on some tools, but more than 90 per cent of the residues were from woody and fibrous plants.

...

Dr Lentfer said hobbits clearly enjoyed a barbecue, as evidenced by the remains of fires and numerous animal bones, especially of baby stegodons (small elephants), komodo dragons and giant rats. The animal bones were found near tools and hobbit remains, and had cut marks indicative of butchery.

Well, that's more than we knew yesterday...

I've seen the "palms facing forward" quote in a few news reports about last week's Dmanisi postcrania paper. It's pretty nonsensical when you see it devoid of context. Consider Bruce Bower's Science News article:

However, the arms of Dmanisi hominids appear more like those of australopithecines, an earlier line of hominids. For instance, unlike people, the new specimens have upper arms that are straight rather than slightly curved, their shoulders are relatively narrow, and their palms are oriented forward rather than inward.

This is quite a vision, isn't it? How exactly is that humerus curved, again? And they stand with their palms forward? What?

OK, so it's tough to give a description of humeral torsion while making it sound important. Your humerus has two ends. The proximal end, called the head, attaches to your shoulder; the distal end is part of your elbow joint. When you are born, the head of your humerus faces toward the back (posteriorly). As you grow up, the humerus twists, so that the head faces inward toward your body (medially). The amount of twist is called the torsion; it is measured relative to the cross-section of the distal end of the humerus.

Nobody really knows what purpose is served by this twisting growth pattern. Presumably, the twisting adjusts for a change in the orientation of the shoulder joint, although that growth pattern has yet to be documented. But humans are more twisted than apes, and low humeral torsion is the key link that people are pointing out between Dmanisi and Homo floresiensis. So the articles are forced to describe it somehow. As a paleoanthropologist, I'm used to describing skeletal changes in punchy ways. Humeral torsion is a challenge -- without a really clear explanation of its function, it is hard to describe it in concrete, memorable terms.

Where does the "palms-forward" interpretation come from? We can trace it to Daniel Lieberman's commentary:

In modern humans, the elbow joint is typically rotated relative to the shoulder joint, so that the forearm naturally hangs with the palms facing inwards; but the new Dmanisi humeri lack torsion, so their palms would have been oriented more forwards. Lack of humeral torsion, a highly plastic and variable feature, suggests something different about the shoulder in these specimens.

Now, I'm sure that most of my readers will be scratching their heads over this one. People carry their hands palm-inward not because the humerus is twisted, but because the radius is habitually rotated across the ulna. That's the same reason why my hands are currently palm-downward on the computer keyboard. The humeral torsion is entirely irrelevant to the palm position when the arms are "naturally hanging" -- I can assure you, all of my children walk with their palms facing inward, despite the fact that their adult humeral torsion hasn't developed.

And of course, if humeral torsion is really about the orientation of the shoulder joint, as Lieberman suggests, then it really has no importance to the function of the elbow at all -- different torsion values would maintain the same lower arm mechanics with different shoulder orientations.

Still, neither the function nor adaptive value of humeral torsion are obvious. As Lieberman mentions, the trait is variable -- Larson and colleagues (2007) reported ranges in recent human populations extending from less than 110° to more than 170°. The value for the adult Dmanisi D4507 humerus is 110°, at the very lowest end of the modern human range; the value for the subadult D2680 is 104°. Humeral torsion continues to increase until age 16 in living people, although most change occurs before age 8 (Edelson 2000).

Larson et al. (2007) suggest that low humeral torsion is related to a short clavicle -- the idea being that the shoulder joint (glenoid fossa) was anteriorly (forward) placed, and the head of the humerus therefore had to face more posteriorly. I'm not sure that explains the low torsion at Dmanisi, since the Dmanisi clavicles aren't especially short -- like the long bones, they are right in the middle of the modern human range. But they might have had an anteriorly-facing glenoid fossa even if their clavicles weren't short, and given the low humeral torsion I suppose they probably did.

None of this means that the Dmanisi people or any other early hominids stood with their palms forward. Paleoanthropologists usually do a really good job of describing anatomy in down-to-earth terms, but humeral torsion seems to be a challenge!

References:

Edelson G. 2000. The development of humeral head retroversion. J Shoulder Elbow Surg 9:316-318. doi:10.1067/mse.2000.106085

Lieberman DE. 2007. Homing in on early Homo. Nature 449:291-292. doi:10.1038/449291a

Larson SG, Jungers WL, Morwood MJ, Sutikna T, Saptomo EW, Duw RA, Djubiantono T. 2007. Homo floresiensis and the evolution of the hominin shoulder. J Hum Evol (in press) doi:10.1016/j.jhevol.2007.06.003

Elizabeth Culotta's article on the Liang Bua conference appears in this week's Science. It's a real treat: around 2500 words worth of description of the proceedings, and quite balanced.

Here's the passage relevant to Laron syndrome:

At the meeting, Dean Falk of Florida State University in Tallahassee, who has concluded from computed tomography (CT) scans of the skulls of LB1 and microcephalics that the hobbit is a new species, tackled the Laron's hypothesis head-on. Hershkovitz and colleagues note that many Laron's patients also lack the sinuses of a normal human head. And although in most people the texture of the mastoid process--the bony bump behind the ear--is spongy and air-filled, in Laron's patients this bone is dense. CT scans of LB1's skull show that it has normal sinuses and a porous mastoid process, Falk said. "We don't think LB1 comes close to looking like their description of Laron's," she said firmly. Hershkovitz responds that some Laron's patients do have normal sinuses, and so their presence does not disprove the hypothesis.

Obviously, I'm not going to quote the whole thing; the paragraph just before that one did a good job laying out the many, many similarities between LB 1 and Laron patients, which I wrote about earlier this summer.

There is some discussion of paedomorphosis, with Christoph Zollikofer weighing in that the anatomy may represent the retention of juvenile traits in a derived, dwarf Homo erectus. I have to say, I don't buy that idea. The proposed juvenile features are the lack of humeral torsion (this develops during early childhood), the "flat face" and the short legs. But it's not clear that the legs are relatively short, and if "flat face" means a lack of facial projection, that is easily explained either by allometry or the fact that its teeth are smaller than H. erectus. The humeral torsion in particular has turned out to be a red herring, since Jungers and Larson have presented that LB 1 is within the range of recent Australians. And, of course, paedomorphosis can't explain the tiny brain -- which is only two-thirds the size of the 1-year-old Mojokerto endocast!

The problem with invoking paedomorphosis is that, of course, you still have to account for why different features are juvenilized at different levels or rates. Since many have attributed the anatomy of living people to a paedomorphosis of Homo erectus characters, presumably LB 1 is a product of a different and distinct version of paedomorphosis. Which is as much as to say the idea is a non sequitur.

Morwood is now arguing for descent from early pre-erectine Homo or Australopithecus, while there is some discussion about whether Dmanisi is a plausible ancestor. These are all attempts to minimize the amount of evolutionary change on Flores; I think that is misguided. If the island really generated a highly derived lineage, then let it be highly derived! On the other hand, the article notes that many are now looking (or seeking funding to look) for similar fossils on lots of other islands, from Sulawesi to the Philippines.

There is some new information on the archaeology, notably the use-wear analysis of some of the artifacts:

Because the tools were found near animal bones, especially baby pygmy elephants called Stegodon, researchers had inferred that the little people used the tools to process meat. But to [Carol] Lentfer's surprise, most of the tools she examined were used for working with woody and fibrous plants, perhaps to craft spear shafts of wood or bamboo or items like traps. "It looks like a tool kit for making other tools," she said in her talk.

This is accompanied by some discussion of the archaeology including comments by James Phillips.

Anyway, read the article. I doubt that we will hear anything new on this score for quite some time.

References:

Culotta E. 2007. The fellowship of the hobbit. Science 317:740-742. doi:10.1126/science.317.5839.740

There was an international meeting in Indonesia about the Flores hominids last week, including scientific presentations and a visit to the cave. I have a regular correspondent who very kindly gave me a short report on some of the proceedings, which included CT scans of the mastoid process (See here for why that may be relevant).

Reporter Elizabeth Culotta was at the meeting, so there will likely be an article about it in Science somewhere in the next few issues.