In 2003, researchers excavating a limestone cave on the remote Indonesian island of Flores made an extraordinary discovery: the 18,000-year-old bones of a woman whose skull was less than one-third the size of our own.
Modern humans were already living throughout the Old World during her time—yet she was physically very different from them. The researchers, led by paleoanthropologist Peter Brown and archaeologist Michael Morwood, both of Australia's University of New England, concluded that the woman represented a previously undiscovered species of archaic human that had survived for thousands of years after the Neanderthals had died out.
They named her Homo floresiensis and nicknamed her the "Hobbit," after the diminutive villagers from J.R.R. Tolkien's Lord of the Rings trilogy. The team has since recovered bones from as many as nine such people, all about a yard tall, the most recent of whom lived about 12,000 years ago.
The Hobbits of Flores created an uproar among anthropologists, causing them to question assumptions about evolution and human origins that had held sway for more than half a century. Some agree that the "Hobbits" are a distinct species. But others, such as anthropologist Robert Martin of Chicago's Field Museum, say the bones belong to small Homo sapiens—perhaps people who suffered from microcephaly, a condition in which the brain fails to grow to normal size. Five years after the initial discovery, says Martin, "nobody's budging an inch."
Some critics say that it would have been impossible for a hominid with a brain the size of an orange to make the sophisticated tools found at Ling Bua Cave—let alone hunt with them—and that they must have been crafted by modern humans. But supporters of the separate species hypothesis modeled the shape and structure of the Hobbit brain and say it could have made the tools.
When Smithsonian anthropologist Matthew Tocheri and other researchers analyzed the Hobbitt wrist, they found a primitive, wedge-shaped trapezoid bone common to great apes and early hominids but not to Neanderthals and modern humans. That fits a theory that Hobbits are less closely related to Homo sapiens than to Homo erectus—the human ancestor that is thought to have died out 100,000 years ago. Morwood has found crude Homo erectus-type stone tools on Flores that may be 840,000 years old.
The skeptics retort that disease is a more likely explanation for the wrist bones. A study this year speculated that the Flores people could have suffered from hypothyroidism, a form of cretinism found relatively frequently in modern Indonesia that, the researchers say, could also produce deformed, primitive-appearing wrists.
Rick Potts, director of the Smithsonian's Human Origins Program, who once doubted that the Hobbits were a separate species, says he's changed his mind: "Flores was this wing in the building of human evolution that we didn't know about. There is no reason that 800,000 years of experimentation could not evolve a small but advanced brain."