for National Geographic News
The "hobbit" humans that lived on the Indonesian island of Flores some 18,000 years ago were actually a population of modern humans stricken with a genetic disease that causes small brains, a new study says.
The argument is being made by a group of scientists who have analyzed all the scientific evidence presented so far about the evolution of the proposed species Homo floresiensis.
The discovery of the hobbit-like humanso-called for their small staturewas first announced in 2004 after a fossil skull and bones of several individuals turned up on Flores.
Preliminary analysis of the remains pegged them as belonging to a totally new species (see hobbit fossil photos).
But gaps in the understanding of how these people existed alongside modern humans and came to wield sophisticated stone tools are coming under greater scrutiny.
In a comment appearing in tomorrow's issue of the journal Science, researchers challenge the evidence used to rule out the notion that hobbits were modern humans with a disease known as microcephaly.
This genetic disorder causes smaller brain size in modern humans and can also lead to short stature.
"My primary concern is with that tiny brain size," said Robert Martin, provost of the Field Museum in Chicago, Illinois, and lead author of the new study.
Martin says that the hobbits' brain size is too small to fit any argument yet made in the scientific literature that H. floresiensis is a separate species.
For example, one theory says that the hobbits could be dwarves derived from Homo erectus, a human ancestor that lived 1.8 million years ago. (Explore an interactive map of human evolution.)
This argument is based on the so-called island rule, which says that evolution drives larger species to become smaller on islands due to a lack of food and other resources.
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