Small Bodied Humans From Palau Revisited

One of the more controversial stories in physical anthropology concerns the small bodied humans found on Palau. The finds were published back in March in PLoS. In that paper Berger et al argued that the material they found represents a population of Palauans that possibly were subject to island dwarfing (although they also imply that Palua could have been populated by small bodied humans who later grew larger). Berger et al also compare the remains to Homo floresiensis and make several suggestions anout small body size and primitive characteristics of the genus Homo (I’ll return to this point later).

Then in August of 2008 Fiztgerald et al published a paper in PLoS criticizing the Berger et al paper. Fitzgerald et al argued that Palau archaeological and skeletal evidence indicates that Palau was colonized by normal sized populations and that these populations were never subject to island dwarfing. There matters rested until a few days ago when Gallagher published a paper on the subject, also in PLoS. Gallagher argues that Palau was colonized by a small bodied population that was never subject to island dwarfing and that grew larger over time. Gallagher’s paper seems to be a direct response to Fitzgerald et al’s paper although, strangely, it is not cited by Gallagher. This is surprising in that Gallagher does mention that Berger’s conclusions have been the subject of some controversy (he cites the Dalton papers in Nature at this point – which had to do with how the finds were discovered and the resulting political and ethical controversy, not with the actual scientific conclusions that are in dispute).
There is another paper out that relates to one of the claims made by Berger et al. In their discussion Berger et al say:

A number of the individual traits observed in the Palauan sample are seen also in specimens from Flores (although the form of these traits may differ in the Palauan sample), some of which have been argued to support the unique taxonomic status of H. floresiensis: small body size, reduction of the absolute size of the face, pronounced supraorbital tori, non-projecting chins, relative megadontia, expansion of the occlusal surface of the premolars, rotation of teeth within the maxilla and mandible, and dental agenesis. These last two features are not argued to be taxonomic markers, but their occurance in specimens from both Palau and Flores is notable, as they may be parallel results of founder effects, genetic isolation and a high inbreeding coefficient, or may simply be a factor of evolutionarily rapid reduction in body and craniofacial size…

This paper will be the subject of my next post.

6 Responses

  1. I’ve never been able to see any reason for a connection between the two populations. Humans have been on Flores for about 800,000 years, plenty of time to evolve small size. And it’s but a relatively short hop across Wallace’s line. But Palau is much more isolated and, as far as I know, there’s no evidence for humans anywhere nearby until about 6000 years ago. I suppose it’s remotely possible that these Flores people reached Palau just before they became extinct on their home island, but extremely unlikely.

  2. As I understand it, the point Berger et al were making is that the population on Palau is completely unrelated to the Flores hominid. However he presents the two cases as an example of possible parallel evolution of island dwarfing in two Homo species. Homo floresiensis is presumably a case of island dwarfing due to isolation of an origina Homo erectus population that arose much longer ago, but survived into the modern era. The population on Palau is Homo sapiens. But the specific unusual features Berger mentions, including the small face with large teeth, especially teeth that seem to fit badly in the mouth and are rotated oddly, in both populations, suggest a possible universal process that operated independently on both populations. That short hop across Wallace’s line prevented all other Homo erectus groups and all other placental mammals from going to Sahel (Australia, New Guinea, Tasmania), remember. It took H. sapiens to get beyond it with the dog/dingo.

  3. OOPS! I meant to say that it took H. sapiens a BOAT to get beyond the Wallace line with the dog or dingo. Homo erectus may not have had one.

  4. Thanks for clearing up what Berger was getting at Diana. By the way, the first Homo sapiens to cross Wallace’s line didn’t take the dingo. That only arrived in Oz about 5 or 6 thousand years ago. But I presume you knew that.

  5. Well, I didn’t know that, terryl, so thanks for adding it. I’m curious, too, Afarensis as to whether you read John Hawks’ reasons for recommending Berger, et al, to be published in PLoS one. He blogged about it, but it almost seemed as though even after Berger made his suggested corrections, that Hawks was not convinced of Berger’s case. It almost seemed as though Hawks was slyly accusing Berger of using the paper to justify funding a vacation in Palau (at least it seemed so to me reading between the lines.)

  6. MIke – I remember reading it at the time and just reread it. Leaving aside the Nature/PLoS kerfluffle, Hawks makes two main points. First, that Berger’s paper is a preliminary report on the material and that the remains should be the subject of further more in depth analysis. Second, that there is evidence of other small bodied populations both on Palau and elswhere. This second point was the subject of Fitzgerald’s paper in PLoS. Fitzgerald’s paper argued that the remains represented a gracile, but normal-sized, human population. I think there was some hand-waving in Fitzgerald’s paper because he also seemed to be saying that even the remains he and Nelson had previously reported were similar to other small bodied populations found elsewhere in the world. Gallagher’s paper seems to confirm that Fitzgerald’s material is, in point of fact, similar to other small bodied modern humans, so the dispute seems to devolve into one about definitions of what constitutes “small bodied”.
    IMHO, I think Hawks was really hinting that the comparisons to Ling Bua were gratuitous and my post on the new Flores articles addresses this comparison.

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