By Guy Gugliotta
Washington Post Staff Writer
Friday, May 19, 2006
More than 1 1/2 years after discovering a race of ancient, "Hobbit"-like little people on a remote tropical island, scientists still do not know what to make of them. Are they a new species of human ancestor? Or were they modern humans suffering from a debilitating genetic deformity?
In dueling papers being published today by the journal Science, researchers offer fresh insights on both sides, seeking to explain how a 30-year-old female with a grapefruit-sized brain could have appeared 18,000 years ago on the Indonesian island of Flores.
A research team led by primatologist Robert D. Martin, provost of Chicago's Field Museum, argues that no human ancestor could reach a weight of 64 pounds with a brain size of only 23.2 cubic inches and be able to make sophisticated tools such as those found with the Hobbit remains.
The Martin team said the Hobbit must have been a modern human with microcephaly -- a condition, usually genetic, in which the brain fails to grow to normal size. "This brain is too small for any explanation besides pathology," Martin said in a telephone interview.
In a rebuttal to the Martin group, a second team led by Florida State University paleoanthropologist Dean Falk defended its earlier research, contending that the Flores skull was nothing like that of a microcephalic and that the remains most likely represent a previously unknown species.
"We are just finishing a big study on microcephalics that confirms our earlier observations," Falk said in a telephone interview. Whereas microcephalic brains shrink with age, causing the inside of the skull to smooth out, the Flores skull is highly convoluted, reflecting the imprint of a fully expanded, fully functioning brain, she said.
Several scientists said, however, that neither of the new papers would be the last word on the controversy. "This argument is going to run and run," said Ian Tattersall, an anthropology curator at the American Museum of Natural History and a bystander in the dispute. "This is an extraordinarily weird and unexpected thing, and, even now, nobody knows what to do with it."
A multinational team led by archaeologist Michael J. Morwood of Australia's University of New England unearthed the remains in a limestone cave on Flores, an island east of the Java Sea.
The team described the find as a new species of dwarf human ancestor that overlapped with modern humans and survived long after Neanderthals died out about 30,000 years ago. In late 2004, the team dubbed the fossil Homo florensiensis , but short stature and the presence of stone tool artifacts soon earned it the nickname Hobbit, after the small but clever villagers from J.R.R. Tolkien's book of the same name.
Martin and several colleagues disputed the find from the beginning, arguing that no creature with a brain as small as the Hobbit's could make finely wrought stone tools and hunt the animals whose remains were found in the cave.
Yesterday, they criticized Falk's research last year describing the Hobbit's brain as remarkably sophisticated, even for its small size, and for saying it did not match up at all with the elongated brain of a typical microcephalic.
Martin's team found that Falk had used the skull of a 10-year-old microcephalic for comparison and said that adults with the condition had skulls that were not unlike the Hobbit's.
"The one they used was the worst possible choice," he said. "Adults look far more normal than the extreme case she took."
Falk, however, disputed the Martin team's analysis, saying that the skull used in the earlier study was a "perfectly dandy microcephalic -- typical, with the sloping forehead and a pointed top," and completely unlike the Hobbit skull.
Rick Potts, head of the Smithsonian Institution's Human Origins Program and an early skeptic, said even newer research, not formally reported, showed in late 2004 that the Hobbit's leg bone, foot and shoulder joint were "quite different from modern humans."
"Martin did not take into account other parts of the skeleton," Potts said. "This is something off the chart as far as being a modern human, or it's a modern human the likes of which we have never seen before. At this point, it's still probably best recognized as a new species. I would say Homo florensiensis still holds."