This is the print version, much longer and more comprehensive, of Science's story on the Hobbit debate. Note that despite considerable media attention to this paper there are many experts who are not convinced.

News of the Week

PALEOANTHROPOLOGY:
Skeptics Seek to Slay the 'Hobbit,' Calling Flores Skeleton a Modern Human

Elizabeth Culotta

Strange new hominid or just another modern human? That's still an open question for the "hobbit" bones unearthed in Liang Bua cave on the Indonesian island of Flores. Their discoverers described them 2 years ago as a new species, Homo floresiensis, but critics have insisted from the start that the leading specimen, a 1-meter-tall, 18,000-year-old skeleton with a brain the size of a grapefruit, was that of a diseased Homo sapiens.

This week, the skeptics laid out their most detailed case yet in the Proceedings of the National Academy of Sciences (PNAS). The paper argues that living people have some of the traits claimed to be unique to H. floresiensis, and that the lone skull is simply deformed. "This is not a new species," says co-author Robert Eckhardt of Pennsylvania State University in State College. "This is a developmentally abnormal individual."

But the hobbit's discoverers and others who have also studied the original specimens are unimpressed. "Complete nonsense," snaps Peter Brown of the University of New England in Armidale, Australia, who did the original anatomical analyses. The paper "cherry-picked features and ignored counterevidence," adds Susan Larson of Stony Brook University in New York, who has linked the hobbit shoulder to an ancient human species, H. erectus (Science, 19 May, p. 983). "Nothing they say has caused me to question my assessment."

The new paper is the first full-length critique in a high-profile journal, and researchers on both sides have long awaited the data in it. The authors include Teuku Jacob of Gadjah Mada University in Yogyakarta, who in a contentious incident borrowed the Flores bones for study in November 2004 (Science, 25 March 2005, p. 1848). In 2005, Jacob and others, including Gadjah Mada colleague Etty Indriati, also studied 76 modern Rampasasa pygmies living only a few kilometers from Liang Bua cave.

The team uses several lines of evidence to challenge the hobbit's novelty. One new argument is that a hominid could not have evolved in isolation on Flores because fossils show that elephants reached the island twice, and so humans probably also arrived more than once; lack of isolation would have prevented the evolution of a new dwarf species, they say.

The team further argues that the skull, part of the specimen labeled LB1, is so asymmetrical that it must have suffered from a developmental deformity. Mirror imaging the left side of LB1's skull and putting those halves together creates a distinctly different face than two right halves put together in the same way.

The paper also reports new data showing that some Rampasasa pygmies lack chins and have odd premolar teeth, features identified as distinctive in H. floresiensis. The original work on the Liang Bua bones "largely looked for 'otherness'--finding reasons to believe that this population is entirely different from anything that has been seen before," says Indriati. "That simply isn't true." The Rampasasa results are "relevant and revealing," agrees Robert D. Martin of the Field Museum in Chicago, Illinois, who has argued in print that LB1 suffered from microcephaly, a genetic disorder marked by a puny brain.

But other experts are fiercely critical of the PNAS paper. "My first reaction was, 'How did this get published? Was there any peer review?' " says brain evolution expert Ralph Holloway of Columbia University. (Eckhardt reports that there were five external reviewers, chosen by the team in accordance with PNAS guidelines.) Holloway adds that he thinks the brain of LB1 shows "possible pathologies" but not for the reasons cited by Jacob and his co-authors.

Others are ready to rebut each point in the paper. The first elephant colonization was too early to have any bearing on the hobbit debate, says Russell Ciochon of the University of Iowa in Iowa City. And the paper's focus on skull distortion is misplaced, adds Brown, because it happened after death, when the specimen was buried deeply in the cave.

As for the treatment of chins, which relies on a photo of a living Rampasasa, it is "superficial indeed," because one must look at a jaw without its covering of flesh to see whether a chin is present, says Colin Groves of Australian National University in Canberra. (Groves and colleagues compare the hobbit to microcephalics and modern humans, including those from Asia, and conclude in a paper in press in the Journal of Human Evolution that it is indeed a new species.) Other details, such as claimed signs of pathology in LB1's leg bones, constitute "a flimsy house of cards," says Bill Jungers of Stony Brook University, who studied the bones last year in Jakarta.

Given these flatly contradictory statements, it's likely to take some time for the field to settle on a coherent view of ancient hobbits. "We have a ways to go before the controversy is resolved," says Indriati. The battle of the shire is far from over.