In-Cahoots FAIL

Two papers in the current issue of American Journal of Physical Anthropology on Homo floresiensis, our dear friend the supposed hobbit. I can’t help but present one sentence from each paper, out of context:

“Insofar as we can tell, LB1, who lived to be a mature adult female, did not suffer from LS [Laron Syndrome] and was not pathological.” (Falk et al. 2009, p. 61, my emphasis)

“As asymmetric craniofacial deformities are not typically seen in a skull with intentional artificial deformation, the aforementioned asymmetric deformities [of LB1] are likely to have been caused by some pathological or abnormal condition.” (Kaifu et al. 2009, p. 180, my emphasis)

Just a little funny that two independent papers supporting the new-species status of H. floresiensis seem to say opposite things. To be fair, when Falk et al. state that LB1 “was not pathological,” they mean that there is no convincing argument that a pathology or disease could cause a modern human skull to look like that of LB1. And Kaifu et al. are referring to the condition of “posterior deformational plagiocephaly,” a not uncommon and presumably non-debilitating phenomenon in recent and historic modern humans, as a result of a persistent application of non-uniform pressure to a child’s developing cranium (like consistently sleeping with one’s head in a certain position). But the ambiguity of words like “pathology” allow the two sentences above to be juxtaposed to make it look like each paper makes contrary arguments.

Nevertheless, the papers do underscore a problem with fossils selected to be the holotypes of new species. Clearly, there is something pathological about LB1, but the extent to which a given pathology undermines the species-status of H. floresiensis is debated. And selection of pathological specimens as holotypes has occurred before: the holotype of Ardipithecus kadabba, one of the earliest and more questionable early hominins, has a first molar socket which “is extensively altered by pathology” (Haile-Selassie et al. 2009, p. 164). And a lot of species, and even genera, have been erected around subadult holotypes, too, which can be problematic.

This is just one of myriad issues we get to deal with in human paleontology.

References
Falk D, Hildebolt C, Smith K, Jungers W, Larson S, Morwood M, et al. 2009. The type specimen (LB1) of Homo floresiensis did not have Laron Syndrome. Am J Phys Anthropol 140: 52-63.

Haile-Selassie Y, Suwa G and White T. 2009. “Hominidae.” In Ardipithecus kadabba: Late Miocene Evidence from the Middle Awash, Ethiopia, Haile-Selassie and Wolde-Gabiriel, eds.

Kaifu Y, Baba H, Kurniawan I, Sutikna T, Saptomo EW, and Jatmiko. 2009. Brief communication: “Pathological” deformation in the skull of LB1, the type specimen of Homo floresiensis. Am J Phys Anthropol 140: 177-185.