By Jonathan Amos
Science correspondent, BBC News
A range of stone flakes were found (scale-bar: 10mm)
Long before a 'hobbit' species of human lived on Indonesia's Flores island, other human-like creatures colonised the area. That much was clear.
But scientists have now been able to
date their presence to at least one million years ago
- some 120,000 years earlier than previously recognised.
The team reports the discovery of these humans' tools in the journal
The group says the finds bring a new dimension to our understanding of the history of Flores.
told BBC News that the location and circumstances of the tools' preservation meant human occupation of the island could extend deep into the past.
"What's really exciting about this is that we effectively have no idea how long hominids have been on Flores," the University of Wollongong, Australia, said.
The hobbit (left) pictured next to the skull of a modern human
The remains of the hobbit, known to science as
, were discovered five years ago at Liang Bua cave.
The diminutive creature's unearthing was a sensation because it indicated a separate human species was living alongside us just 18,000 years ago.
Flores has witnessed intensive paleontological investigation ever since.
The famous H. floresiensis cave is located in the west of the island. The new discoveries come from the Soa Basin, an area in central-west Flores.
A dig site there, known as Mata Menge, had already revealed tools dated to 880,000 years ago. Now, just 500m away but much deeper in the sediments, an international team has identified even older artefacts.
The site, referred to as Wolo Sege, has yielded more than 40 stone flakes. These were hand tools, probably used to butcher meat among other tasks.
The dig site at Wolo Sege is in central-west Flores
Many show evidence of being swept along in a stream before being laid down. Critically, however, their burial is capped by a layer of volcanic ash that has been accurately dated to just over one million years ago.
The scientists can say nothing about who used these tools. There is an insufficient number at this stage to assess which culture produced them. But their mere discovery raises some interesting issues.
For example, the Mata Menge discoveries are associated with the disappearance in the deposition record of a number of animal species, such as a pygmy elephant and a giant tortoise. The conclusion that had been drawn from their extinction was that human hunters arriving on the island had hunted them out of existence.
But the Wolo Sege findings put a new perspective on this story because they show humans must have been living side by side with the animals for at least 120,000 years.
Brumm and colleagues tell
that it may be difficult to find artefacts in the Soa Basin that are older than the Wolo Sege flakes. The reason is that the tools were lying just on top of what is the rock base in the area (the flank of a volcano).
"Anything inside that bedrock, or within any layers we identify in the bedrock, if they contain stone tools they must be at least 1.86 million years old," said Dr Brumm.
"So, a priority for further research this year is to do a more intensive survey throughout the basin and follow up these bedrock outcrops."
The notion that Flores may have a very deep history of occupation will feed into the debate over H. floresiensis' origins.
Many scientists believe the creature evolved from a much larger-bodied species,
, that became isolated and shrunk over time. Others point to features in the hobbit's body - such as the length its feet to the shape of its shoulder girdle - that are very primitive and not what one would expect in dwarfed H. erectus.
These researchers have put forward the idea that H. floresiensis may have evolved from more archaic creatures that left Africa to colonise Asia even before erectus.
"Our discovery at Wolo Sege will certainly open the door to this contentious theory," said