Kakadu site shows 65,000 years of human occupation

Thursday, 20 July 2017

New evidence uncovered by a team of archaeologists and dating specialists, including the University of Adelaide, shows human occupation of Australia for at least 65,000 years – much longer than other estimates of closer to 50,000 years.

Published today in the journal Nature, the new discoveries were made at Madjedbebe, a rock shelter in northern Australia. The site is on Mirrarr land within the Jabiluka mineral lease, surrounded by the World Heritage-listed Kakadu National Park.

The researchers, led by the University of Queensland and in collaboration with University of Wollongong, worked in partnership with Mirarr Traditional Owners and the Gundjeihmi Aboriginal Corporation.

The paper adds an important new dimension to the debate about the timing of human arrival in Australia and past human interactions with Australian ecosystems.

“It pushes back the initial human occupation estimate by some 10 thousand years or more, and supports a longer Aboriginal connection with the continent than previously thought,” says Dr Lee Arnold, ARC Future Fellow at the University of Adelaide.

“Intriguingly, the new occupation age implies at least 20,000 years of overlap between humans and the megafauna in the far north of Australia. This latest evidence suggests that the causes of Australian megafauna extinction may be much more complex than is often assumed.”

The site, which was formerly known as Malakunanja II, had been previously studied in the 1970s and late 1980s. However, a number of question marks remained over the context and age of the stone tools.

More than 10,000 artefacts have been revealed, including the oldest ground-edge stone axe technology in the world, the oldest known seed-graining tools in Australia, and evidence of finely made stone points which may have served as spear tips.

The University of Adelaide helped to corroborate the new dating results for the site using optically stimulated luminescence (OSL) chronology.

“The archaeological team was aware that the new dating results needed to be particularly rigorous given the antiquity of the site,” says Dr Arnold. “I was asked to perform a ‘blind’ OSL dating test of some of the samples that had been independently dated by our colleagues at the University of Wollongong.”

The results were identical and confirmed the accuracy of the site’s chronology – independent crosschecking between multiple dating laboratories, which represents a benchmark chronological study for Australian archaeology.

“Significant advances in dating methodologies, particularly single-grain OSL techniques and statistical age-depth modelling, have meant that the chronology of archaeological sites like Madjedbebe can now be resolved with much greater accuracy, precision and resolution,” says Dr Arnold.

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