Newfound stone tools suggest the evolutionary history of the "hobbits" on the Indonesian island of Flores stretches back a million years, a new study says—200,000 years longer than previously thought.
The hobbit mystery was sparked by the 2004 discovery of bones on Flores that belonged to a three-foot-tall (one-meter-tall), 55-pound (25-kilogram) female with a grapefruit-size brain.
The tiny, hobbit-like creature—controversially dubbed a new human species, Homo floresiensis—persisted on the remote island until about 18,000 years ago, even as "modern" humans spread around the world, experts say.
Found in million-year-old volcanic sediments, the newly discovered tools are "simple sharp-edged flakes" like those found at nearby sites on Flores—sites dated to later time periods but also associated with hobbits and their ancestors—said study co-leader Adam Brumm, an archaeologist at the University of Wollongong in Australia, via e-mail.
The finding implies that a culture of stone tool wielding ancient humans, with origins in Africa, survived on the island for much longer than previously believed, according to the new research, published online today by the journal Nature.
"That's exciting," because it suggests that by a million years ago, early humans had covered more ground on their exodus from Africa than previously thought, said paleontologist Chris Stringer of the Natural History Museum of London, who wasn't involved in the new study.
(Read "Flores Find: The People Time Forgot" in National Geographic magazine.)
Hobbit Ancestors off the Hook?
The stone-and-bone record had suggested that the hobbits' ancestors—perhaps upright-walking-but-small-brained Homo erectus—left Africa about 1.5 million years ago and reached Flores by 880,000 years ago.
Once there, it's been thought, the hobbit ancestors quickly hunted a pygmy elephant species and a giant tortoise species to extinction.
The date of the newly discovered stone tools, though, suggests elephant and tortoise died off a hundred thousand years after Flores's colonization —indicating that the early Flores colonizers' role in the extinction "must have been minimal," study co-leader Brumm said.
What's more, these early colonizers could have been more primitive than H. erectus—"that is our working hypothesis," he added.
When the bones of the hobbit were first reported in 2004, the discovery team suggested they belonged to a unique species, Homo floresiensis, that had descended from Homo erectus.
"I think that's looking increasingly likely from its anatomy," said the Natural History Museum's Stringer.
Hobbit Findings Questioned
Not everyone is ready to accept the new date.
"I have no problem with hominins"—human ancestors—"being on Flores at 1.2 million years ago," anthropologist James Phillips said. "After all, they were on Java by around 750,000 [years ago]."
But the fact that the implements were found in million-year-old volcanic sediments doesn't guarantee the artifacts are a million years old, said Phillips, an emeritus professor with the University of Illinois at Chicago, said via email.
"There are many ways"—such as water-driven processes—"in which artifacts can move through sediments," Phillips said.
He's also dismayed that the new study assumes that stone-tool technology changed little on Flores for more than a million years.
"Everywhere else on Earth, change was slow but always—and I emphasize always—occurred."
Controversy is nothing new in hobbit science, with many experts still at odds over whether Homo floresiensis is a separate species at all.
Hobbit Ancestors Rafted to Flores?
Regardless of what they were and when they arrived, the question remains: How did primitive humans get to Flores in the first place?
The Natural History Museum's Stringer buys into a theory that they may have migrated from Africa, perhaps on foot, to the island of Sulawesi (map). There, the ancient humans may have been washed to sea by a tsunami—currents off Sulawesi flow southward, toward Flores.
"These creatures most likely got moved on rafts of vegetation," he said.
To help shore up this theory, the team behind the original hobbit discovery is currently looking for evidence on Sulawesi that would prove humans occupied the island even earlier than they did Flores.