Skeletal remains said in 2004 to be that of a new small-statured hominid species, dubbed the "hobbit," are simply the ancestors of modern human pygmies who live on the same Indonesian island today, according to an international scientific team.
The remains of several individuals, estimated to be about 18,000 years old, were found in the Liang Bua cave on the island of Flores in the central part of the Indonesian archipelago.
The new analysis, done by Indonesian, American, Australian and Chinese researchers, purports that the claims of a new species, "Homo floresiensis," are incorrect.
The team argues that the single skull among the remains shows signs of microcephaly, a condition in which an individual's head and brain are much smaller than average for that person's age and gender.
"Our work documents the real dimensions of human variation here," said Dr. Robert B. Eckhardt, professor of developmental genetics and evolutionary morphology at Pennsylvania State University.
The skull belonging to the most complete skeleton, dubbed LB1, "looks different if researchers think in terms of European characteristics, because it samples a population that is not European, but Australomelanesian, and further because it is a developmentally abnormal individual, being microcephalic," Eckhardt explained.
The results were published Monday in the online edition of the Proceedings of the National Academy of Sciences.
The group of scientists who found the remains proposed in 2004 that Homo erectus, the first hominid to expand beyond Africa, first inhabited Flores about 840,000 years ago, a date established by stone tools found on the island.
Then, due to the common "island effect" which shrinks large-bodied species over time, Homo erectus eventually evolved into the dwarf-sized Homo florensiensis.
But the hypothesis partly rests on the assumption that after the initial Homo erectus influx, there was no further hominid migration onto Flores until modern humans arrived about 15,000 years ago, after the "hobbits" had died out.
Eckhardt and his colleagues contend that that scenario was highly unlikely.
Pygmy elephants migrated to Flores at least twice during the 825,000 years in question, they point out, and there were several ice ages that would have lowered sea levels by so much that the island would have been separated from its neighbors by only a few miles, easily crossed by boat.
As for the LB1 skeleton's unusual cranium, face, teeth and stature, Eckhardt's team found that some of the key features previously said to be indicative of a new species still are present in Flores' indigenous Rampasasa pygmies (sometimes spelled Rampapasa), one community of which lives less than a mile from the Liang Bua cave.
Other features of the skull, such as the extremely small braincase and the facial asymmetry, were indicative of microcephaly, the article argues.
"To establish a new species, paleoanthropologists are required to document a unique complex of normal traits not found in any other species," Eckhardt said in a statement Monday. "But this was not done. The normal traits of LB1 were not unique, and its unusually small braincase was not normal."
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