Australian paleontologists say they've found more bones of a new human dwarf species, popularly known as prehistoric hobbits.
Last year, Prof. Mike Morwood, of the University of New England in Armidale, Australia, and his team announced the discovery of what appeared to be an adult female less than one metre tall that walked upright with a grapefruit-sized skull.
The skeleton, called LB1, was dated to about 18,000 years ago, meaning modern humans may have shared the planet with other hominids much more recently than thought.
The remains were found on the Indonesian island of Flores, east of Java, leading the team to call it Homo floresiensis or "Man of Flores."
The find touched off a scientific debate over whether the specimen:
- Is a naturally tiny species of early human as the team proposes.
- Is a modern human that suffers from microencephaly, a genetic disorder resulting in small brain size.
- Is a pygmy human, not a new hominid species.
Now, Morwood's team describes more fossil remains, including a jaw, arm and other similarly small bones that they say came from nine individuals. Two mandibles also share dental features and lack a chin, a portion of the jaw common to all Homo sapiens regardless of size.
"We can now reconstruct the body proportions of H. floresiensis with some certainty," the researchers write in the Oct. 11 online issue of the journal Nature.
"The finds further demonstrate the LB1 ... is not just an aberrant or pathological individual but is representative of a long-term population."
Building fires, making toolsThe paleontologists suggest the new species evolved its small size because of the limited resources, small populations and predators on the island.
"What captures the imagination is that dwarfing might have occurred in humans, who often buffer themselves from natural selection through cultural means such as tool production and fire-making, both evident at [the fossil site]," wrote Daniel Lieberman, of the Peabody Museum at Harvard University in a journal commentary.
Lieberman suggests the island-dwarfing hypothesis could be tested by finding more, older fossils from Flores. Three-dimensional analysis of the shape of the fossils independent of size could also help reveal if Homo floresiensis is simply a scaled down version of another early human species, he said.