Sunday, March 06, 2005

Critics silenced by scans of hobbit skull
NATURE - Rex Dalton
Comparisons with pygmies and chimps bolster new species claim.

A computer-generated model of the skull of Homo floresiensis, our diminutive human relative, confirms that the controversial specimens from Indonesia do indeed represent a new

The study of the creature's brainpan shows that it was neither a pygmy nor an individual with a malformed skull and brain, as some critics contend. This lends support to the discovery team's assertion that the metre-tall specimen belongs to a species distinct from Homo erectus.

A skull and bones from eight H. floresiensis individuals were unearthed in a cave on Indonesia's island of Flores over 2003 and 2004 by a team of Indonesian and Australian researchers. The new species, which may have been alive as recently as 18,000 years ago, was reported in Nature 1,2 last October. It generated huge fanfare among scientists and anthropology buffs.

But a handful of critics have questioned the scientific description, contending that the specimens represent a tribe of pygmies, with at least one member having a deformed skull and brain, a condition called microcephaly.

Now the study published online in Science, by US researchers collaborating with discovery team members, effectively dispels that criticism 3.

"We have no doubt it is not a microcephalic," says lead author Dean Falk, a palaeoanthropologist at Florida State University in Tallahassee. "It doesn't look like a pygmy either."

Star cast

The research explains how a computerized tomography scan of the H. floresiensis skull was used to create a facsimile cast at Washington University in St. Louis, Missouri. Then the cast, in particular, the area where the brain fits, was compared with casts from a chimpanzee, H.erectus, a contemporary Homo sapiens and a microcephalic from Europe. Analysis was also done on a number of other specimens, including those of human pygmies.

The comparisons show the creature that lived on Flores Island "is definitely a new species", says Falk.

Ralph Holloway, a palaeoanthropologist at Columbia University in New York, agreed with the interpretation by Falk and colleagues. "I think she did a good job in her description and is right."

For discovery team members, the conclusion was welcome news. "Together with all the other evidence, this paper makes it very clear that H. floresiensis is not an aberrant individual with a pathological condition," says Michael Morwood, an archaeologist from the University of New England, Armidale, who was co-leader of the team.

Morwood was also excited that the Falk cast seems to indicate advanced development of the front lobes of the brain, where reasoning occurs. Such brain development could be evidence for his theory that the species was able to make or refine stone tools, such as those found with the bones.

Brown P., et al. Nature 431, 1055 - 1061 (2004). Article PubMed ChemPort
Morwood M. J., et al. journal 431, 1087 - 1091 (2004). ChemPort
Falk D., et al. Science published online. doi:10.1126/science1109727 (2005). Article