Researchers have unearthed the bones of seven more adults belonging to the species Homo floresiensis--an extinct group of tiny humans first discovered on the Indonesian island of Flores last year. The new finds include a child's leg bones so tiny that they snuggle neatly on a bank note and an adult's lower jaw estimated at 15,000 years old. The age bolsters the case that the "hobbits" inhabited the island's Liang Bua cave for thousands of years, say the researchers.
News of the first, nearly complete H. floresiensis skeleton last year sent anthropologists reeling. Some believed that the specimen represented a new species of human, while others argued that it was simply a modern human with microcephaly--a condition causing abnormal smallness of the head (ScienceNOW , 27 October 2004).
The discovery team, led by Michael Morwood of the University of New England in Armidale, Australia, found the latest bones in Liang Bua cave during the 2004 field season. The H. floresiensis specimens range from 12,000 to at least 74,000 years old. The team also found stone tools, charred pebbles, and extinct animals, including a dwarf elephant called Stegodon in the hominid-bearing layers, they report 13 October in Nature.
Researchers familiar with the paper say it underscores how strange the little Flores people were. The first skeleton uncovered, thought to be that of a 30-year-old female, has a tiny skull and modern-looking face and teeth perched atop a short, chunky body. She has relatively long arms and short legs, and a bizarrely rotated upper arm bone not seen in any other ape. Paleoanthropologist and team member Peter Brown, who described the bones, says the distinctive similarities among the specimens confirm that they are a new species rather than diseased moderns. For example, the two jaws both lack a chin, considered a hallmark of modern humans, and the long bones are unusually robust, or thick for their length.
"This destroys the argument that the first skeleton was an aberrant individual," says paleoanthropologist Russell Ciochon of the University of Iowa in Iowa City. However, a few researchers remain open to the idea of microcephaly. Anthropologist Robert D. Martin of the Field Museum in Chicago, Illinois, notes that microcephaly often runs in families and that bones can be jumbled in caves, boosting the chances of finding several microcephalic individuals together. "I'm not 100% convinced it's microcephaly, but I am convinced that that brain size doesn't go with those tools," he says.
More on H. floresiensis