Hobbit Controversy Continues -- Claims of Cretinism Rejected on Several Counts. (March 6, 2008)

A paper by Peter Obendorf of RMIT University in Melbourne (Obendorf, P. et al. Proc. R. Soc. B doi:10.1098/rspb.2007.1488 (2008)) has made the mass media by suggesting prenatal iodine deficiency produced the hobbit.

It raises the question once again whether the conclusion that Homo floresiensis the so-called hobbit (fossils of which were found on the Indonesian island of Flores) is a species separate from Homo Sapiens or just a malformed representative.

The unearthed 18,000-year-old remains are consistent with the beings being just over 1 metre tall, with a brain one-quarter the size of modern humans and primitive skeletal features similar to those of earlier human relatives.

To date bones from 12 separate hobbits had been unearthed in the original Liang Bua cave, but only one skull has been found.

Several sources have championed the explanation that the hobbit was in fact a human who had a developmental disorder called microcephaly, in which the head is smaller than usual, while an Israeli team published a report proposing that the hobbit had a growth disorder called Laron syndrome.

Proponents of the distinct species proposal have continued to counter the claims of their detractors and to date neither side has landed a knockout blow.

Now Peter Obendorf suggests as "a tentative hypothesis", that the hobbits were the product of iodine deficiency during prenatal development and subsequent hypothyroidism which resulted in cretinism.  Obendorf adds he thinks he and his colleagues "are on the right track". They now are seeking access to the original specimen, having thus far examined only casts.

The Obendorf paper notes that the pituitary fossa, a notch in the skull that houses the pituitary gland, is enlarged both in the cast of the one existing hobbit skull and in cretins. They also report other similar features. The top of the upper arm bone of both are unusually straight and untwisted, and both have relatively thick or limbs.

R. D. Martin of the Field Museum in Chicago, Illinois, a strident critic of the separate species hypothesis, told ScienceNow: "I am delighted to see that yet another independent group of established scientists has come to the conclusion that [the hobbit skull] is a pathological specimen". But he still prefers microcephaly a compelling hypothesis to explain the hobbit's undersized brain.

On the other hand Elizabeth Culotta writes in ScienceNow:

Those studying the original specimens and casts thereof aren't buying the latest charge, however. "No way, Jose," says Dean Falk of Florida State University in Tallahassee, who did computed tomography (CT) scans of the lone hobbit skull, LB1. She and others challenge the team's conclusions point by point. For example, using CT scans instead of published photos, Falk finds that the hobbits' pituitary fossa is no larger than usual. The fossa size "is the crux of the argument vis-à-vis cretinism, so pretty much game over," says William Jungers of Stony Brook University in New York state. "The rest is pure speculation." He says there's no evidence that cretins' brains are as small as that of LB1. Debbie Argue of Australian National University in Canberra adds that Obendorf's team has not accounted for hobbit cranial oddities such as a mounding of bone above and around the orbits.

Ralph Holloway, a self-described "fence sitter" on the hobbit question, says he's not leaving his fence yet. "I think [Obendorf's team] is dead wrong on the size of the pituitary fossa," he says, given his own inspection of a cast of the inside of the hobbit skull. "The bottom line is that almost all of the claims for pathology fail to provide evidence that matches what one sees in the Flores remains."

Palaeoanthropologist Peter Brown, who together with Michael Morwood, both of the University of New England, is one of the original discovers of H. floresiensis is also critical of the cretin theory. He told Nature: "I am the only person on the planet to have seen what’s left of the pituitary fossa. It is very poorly preserved and not capable of meaningful measurement."