The Liang Bua report

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