Archaeologists believe they hold the key to unravelling the mystery of "hobbit" humans on a remote island.
Excavations on Indonesia's Sulawesi island have uncovered stone implements dating back over one million years.
The artefacts consist of sharp-edged fragments crafted from larger stones, probably sourced from local waterways.
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These discoveries at the Calio site demonstrate that early humans established tool-making operations and hunting activities on Sulawesi.
Earlier evidence had placed human occupation of the Wallacea archipelago at roughly 1.02million years ago.
This was based on implements found at Flores' Wolo Sege site, whilst Sulawesi's Talepu location showed habitation from merely 194,000 years ago.
However, the discovery indicates that ancient humans navigated maritime barriers across Southeast Asia to settle distant islands much sooner than experts had calculated.
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The discoveries could be the key to unravelling the mystery of 'hobbit' human
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The timing coincides with the period when Homo erectus is believed to have reached Flores.
This is when the neighbouring island where the small-statured Homo floresiensis later developed.
Scientists theorise that Homo erectus experienced extensive dwarfism over hundreds of millennia on isolated Flores, eventually becoming the "hobbit" species.
The newly dated Sulawesi tools suggest that early humans dispersed across the region's islands simultaneously rather than in a gradual pattern, as previously assumed.
These findings transform scientific understanding of human dispersal across the Wallace Line, the biogeographical boundary where distinctive fauna developed in seclusion.
"Sulawesi is a wild card. It is like a mini-continent in itself," study co-author Dr Adam Brumm said.
He added: "This discovery adds to our understanding of the movement of extinct humans across the Wallace Line, a transitional zone beyond which unique and often quite peculiar animal species evolved in isolation.
"If hominins were cut off on this huge and ecologically rich island for a million years, would they have undergone the same evolutionary changes as the Flores hobbits?
The new discovery means humans could have inhabited the Sulawesi islands earlier than thought
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"Or would something totally different have happened?"
Despite the significance of the stone implements, researchers have yet to discover any fossilised human remains at Calio.
Dr Brumm continued: "It's a significant piece of the puzzle, but the Calio site has yet to yield any hominin fossils.
"So while we now know there were tool-makers on Sulawesi a million years ago, their identity remains a mystery."