Wednesday, January 27, 2010

What The Small-Brained Hobbit Reveals About Primate Evolution

hobbit brainIs bigger always better? When it comes to brain size, that has long been the prevailing theory—at least among big-brained humans. But a new analysis shows that in the course of primate evolution, brains and brawn haven't always been on the rise.

Ever since a petite female Homo floresiensis (or "hobbit") was described in 2004, scientists have been debating whether this recently extinct hominin could have evolved to have such a small noggin or if this specimen—the only one for which a skull has been found—was an aberration.

The Indonesian individual stood at just about one meter high and had a brain about a third the size of modern humans. Despite these striking size differences, some H. floresiensis fossils date to just 13,000 years ago—which means they would have lived alongside brainy humans for some 187,000 years. Some researchers propose that she and her clan were modern descendents of Homo erectus and had devolved to their diminutive stature because they lived on an island (a phenomenon documented in other species known as insular dwarfism) or that her particular errant body and brain size were due to an underlying pathology, such as dwarfism or an oversized pituitary gland.

Others, however, posit that H. floresiensis is from a more primitive lineage and evolved—for whatever reason—to have this smaller brain.

A new study, published online January 26 in the journal BMC Biology, brings some new perspectives to the table, examining size trends in primate evolution and finding that brains and bodies don't always get bigger over time.


Full story here.
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