Indonesian "Hobbits" disappeared when modern humans arrived

The world's earliest humans, dubbed "hobbits," may not have co-existed with modern humans as first thought with new research published Thursday pushing back their disappearance by 50,000 years after new excavations revealed flaws in the original dating.

The new timeframe coincides with the arrival of humans from Australia, giving weight to the theory the modern Homo sapiens played a role in their demise, Griffith University Associate Professor of archaeology and geochronology, Maxime Aubert, said.

"The science is unequivocal," Aubert said in a statement on Thursday.

"The youngest Hobbit skeletal remains occur at 60,000 years ago but evidence for their simple stone tools continues until 50,000 years ago. After this there are no more traces of these humans."

The research, which measured the amount of uranium and thorium inside the Homo floresiensis fossils to test their age and published in the scientific journal Nature on Thursday, overturns the original dating that put the species disappearance as late as 12,000 years ago.

Discovered in a cave on the Indonesian island of Flores in 2003, the scientific community has been divided on whether Homo floresiensis was in fact a new species, or a modern human affected by disease such as Down syndrome or iodine deficiency.

The study's co-author, University of Wollongong Professor Bert Roberts, told Australia's national broadcaster when he made the original discovery, the dated disappearance of "the hobbit" at 12,000 years ago was always strange.

"Something that stuck out at the time which we could never get our head around was how could these little people have survived on Flores some 40,000 years after modern humans had reached Australia," Roberts said.

"How could you have 40,000 years of overlap between a species such as us (Homo sapiens), which is well known to be a disturbing factor wherever we land, and this tiny residual group."

Another eight-years of excavations at the large, complex site on Flores island led to a much clearer understanding of the archaeological layers, suggesting the original team mistakenly collected samples to date layer containing the bones from an overlying layer of similar composition, but far younger.

The researchers concluded the tiny cave dwellers evolved from an older branch of the human family that had been marooned on Flores for at least a million years.

Griffith University archaeologist Dr Adam Brumm, who also participated in the study, said the primitive humans -- who likely inhabited other caves which may yield more recent signs of their existence -- probably suffered the same fate that fell Europe's Neanderthals, in that they were out-competed and replaced by humans within a few thousand years.

"They might have retreated to more remote parts of Flores, but it's a small place and they couldn't have avoided our species for long," Brumm said, though there is no direct evidence yet to suggest the primitive and modern human interacted.

The extinction of Homo floresiensis follows a traditional pattern observed in Australia in the same time frame where mega fauna, or the giant ancestors of endemic Australian kangaroos and wombats, disappeared soon after modern humans arrived.

"At the same time hobbits go out, we lose all the giant animals that we know about," Roberts said.

"We can't point a finger at modern humans and say it was us that drove them (the hobbits) to extinction (yet) but at least it puts the disappearance of the hobbits in the same timeframe as the arrival of the modern humans."