Flores (Indonesie): "Hobbits" disappeared when modern humans arrived
Liang Bua cave: Sediment layers in this cave misled experts about the age of "hobbit" bones there. Liang Bua Team
The disappearance of "hobbits" on the Indonesian island of Flores has been pushed back to 50,000 years ago after excavations revealed flaws in the original dating of the controversial species of primitive humans.
The new timeframe coincides with the arrival of modern humans in Australia and gives weight to the theory Homo sapiens may have played a role in the demise of Homo floresiensis.
Data published in Nature, showed skeletal remains of Homo floresiensis - discovered in a cave on the Indonesian island of Flores in 2003 - are between about 100,000 and 60,000 years old, and associated stone tools date between 190,000 and 50,000 years.
This overturns original dating that suggested the hobbit and its tools had disappeared as late as 12,000 years ago.
Professor Bert Roberts, of the University of Wollongong's Centre for Archaeological Science, who was part of the team that made the original discovery in 2003 co-authored the latest study.
Scientists originally misled by layers of sediment
When Homo floresiensis was announced to the world in Nature in 2004, it triggered great debate in sections of the scientific community.
Some argued the first specimen to be described - an adult female about one-metre tall with an extremely small, chimpanzee-sized brain - was not a new species, but a modern human that was simply affected by diseases such as Down syndrome or iodine deficiency.
Professor Roberts said original research that put the disappearance of the "hobbit" at little as 12,000 years ago had always seemed unusual.
"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," he 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."
These sediments being excavated are between 100 and 60 thousand years old and contain evidence of Homo floresiensis Liang Bua Team
Professor Roberts said eight years of work at the cave site had answered this question after discovering rock layers of the cave were more complex than originally thought.
He said the area where the original skeleton was found was a "remnant pedestal" of older sediment that had remained while the area around it had been eroded away. Over 20,000 years this pedestal had been covered by "younger" sediment.
The ages of those younger overlying sediments were originally thought to apply to the 'hobbit' remains, Professor Roberts said.
However the new excavations and dating techniques unavailable in 2004 showed this was not the case.
Professor Roberts said the team dated charcoal, sediments, flowstones, volcanic ash and even the Homo floresiensis bones themselves to arrive at the new timeline.
He said the new dates suggested the extinction of Homo floresiensis followed a traditional pattern.
"At the same time hobbits go out we lose all the giant animals that we know about," he said. "The pygmy stegodon [a relative of the elephant], giant marabou stork and vultures all disappear at the same time."
The loss of the megafauna in Flores after the arrival of modern humans was "very reminiscent of the Australian situation" where the giant ancestors of kangaroos and wombats disappeared soon after modern humans arrived.
Professor Roberts said there was no evidence yet to suggest the "hobbits" interacted with modern humans or other human groups, such as the Denisovans.
"We can't point a finger at modern humans and say it was us that drove them [the hobbits] to extinction but at least it puts the disappearance of the hobbits in the same timeframe as the arrival of the modern humans," he said.
What is a "hobbit"?
An adult "hobbit" stood about a metre tall and weighed about 25 kilograms
Had small brains, about the size of a chimpanzee, and relatively large feet
Flores locals talk of ancient tales of "ebu gogo" people who lived in caves
Locals say they were short, stocky, not bright, stole food and could not cook
Some suggest these legends may be based on fact rather than fiction