Getting to Flores
New evidence from the hobbit's wrist, skull, brain, shoulders, and feet are also rewriting when scientists think the tiny humans arrived on Flores.
Researchers had initially suggested that the fossils represent a descendent of Homo erectus that had reached Asia after that species had left Africa about two million years ago. (Explore a time line of human migration.)
But the new analysis hints that the hobbit's ancestors were slightly more primitive.
"We feel that all these different lines of evidence suggest that something a little earlier than erectus may have gotten out of Africa got out to Indonesia and got onto Flores," Harcourt-Smith said.
Once on Flores, the picture remains fuzzy as to whether the hobbit evolved to become smaller or stayed essentially the same, he added.
In a commentary accompanying the Nature article, Harvard University paleoanthropologist Daniel Lieberman writes that he, like many other scientists, sat on the fence, "waiting for more evidence about the nature and form of H. floresiensis."
Now the growing body of research suggests the hobbit "evolved from a species that was anatomically more primitive than the classic H. erectus from Asia," he said.
The hobbit's uniqueness is lent further support, Lieberman added, by another study, also appearing in this week's Nature, which examined the creature's unusually tiny brain.
The hobbit's brain is disproportionate to the rest of its body, some experts have argued, and that's a sign that the creatures were modern humans with a genetic condition called microcephaly.
But a team from London's Natural History Museum studied dwarfing of modern hippos on the island of Madagascar. They found that the animals' brains became even smaller over time than models had predicted, lending support to theories that the hobbit's brain size could have been a result of island living.
Robert Eckhardt, an evolutionary biologist at Pennsylvania State University, remains skeptical about claims that the hobbit represents a unique species.
Each new paper published by supporters of the "new species" designation contradicts one or more of their previously published papers, he commented in an e-mail exchange.
"In science, poor hypotheses identify themselves by needing ad hoc revision after revision. This is what is happening with increasing visibility in the [descriptions] of 'Homo floresiensis.'"
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