Old debates die hard in the study of human origins. In October 2004 paleoanthropologists announced the discovery of a new human species that lived as recently as 17,000 years ago on the Indonesian island of Flores. Homo floresiensis, also known as the hobbit, was an overnight sensation. Just over a meter tall, with a brain a third the size of our own, the creature was in many ways as primitive as our 3.2-million-year-old relative, Lucy. Yet it was a contemporary of Homo sapiens and apparently made relatively advanced stone tools and hunted large animals — activities associated with brainier humans. Noting the conflicting observations, skeptics immediately countered that the bones belonged to a diseased H. sapiens individual, not a new species. And so began a battle over bones that continues to this day.
The latest attack comes from some of those same doubters. In a paper published in August in the Proceedings of the National Academy of Sciences USA, Maciej Henneberg of the University of Adelaide in South Australia and his colleagues argue that the bones of the most complete individual from the site, known as LB1, exhibit features indicative of Down syndrome. They base their argument on the small circumference of LB1’s skull, among other traits.
Hobbit team members have been quick to reject the Down syndrome claim. William Jungers of Stony Brook University notes that there is no known case of Down syndrome (ancient or modern) in which an individual had a head circumference as small as LB1’s. Nor do people with Down syndrome share LB1’s other distinctive features, such as her projecting midface and thick braincase walls.
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Still, even if the new work does not prove that LB1 had Down syndrome, the possibility remains that she suffered from some other pathology that produced her strange features. Biological anthropologist Thomas Schoenemann of Indiana University Bloomington, who studies brain evolution, notes that proponents of H. floresiensis have insisted that scientists treat LB1 as representative of a new species unless a specific developmental anomaly can be matched to it. But that position “is simply not reasonable, given how odd [LB1] is with respect to the rest of the [human] fossil record,” he says. “What we really need are more specimens and some trail of fossils that shows us how LB1 got to Flores” while retaining characteristics of australopithecines for more than a million years, Schoenemann observes. Ongoing excavation of the Flores site has yet to yield more small skulls.
