Humans arrived in the arid interior of Australia 10,000 years earlier than previously thought, archaeologists working at a site in South Australia believe.

Researchers excavating a rock shelter in the Flinders Ranges have unearthed ancient artefacts dating from up to 49,000 years ago – just 1,000 years or so after humans arrived in Australia – including burnt eggshells and stone tools. A bone from a now-extinct creature known as a Diprotodon optatum – a huge wombat-like marsupial – was also retrieved, offering the clearest evidence yet that humans interacted with such creatures.

An artist’s impression of an adult Diprotodon optatum, a giant megafauna herbivore thought to have weighed around three tons and have been approximately four metres long. Photograph: Peter Murray

The discovery of some of the earliest artefacts of their kind in Australia, including certain stone and bone tools as well as red ochre and gypsum pigments, has challenged ideas of how and when such items came to be used.

“The old idea is that people might have come from the East, from the Levant, out of Africa, and these modern humans may have come with a package of innovative technologies,” said Giles Hamm, first author of the research from La Trobe University, Australia. “But the development of these fine stone tools, the bone technology, we think that happened as a local innovation, due to a local cultural evolution,” he added.



Published in the journal Nature, the research reveals evidence of human activity 49,000 years ago in the Warratyi rock shelter - a site, discovered by Hamm around five years ago.

Hamm believes the new findings point to humans rapidly moving south after their arrival in Australia, before becoming “trapped” in the Flinders Ranges as the aridity of the region increased - a situation that could have driven the development of new tools and practices.

The Warratyi rock shelter, where newly-discovered artefacts have challenged ideas of how and when certain tills and pigments were first used in Australia. Photograph: Giles Hamm

Excavations revealed artefacts including stone, bone and quartz tools, which the team painstakingly mapped to their locations within the layers of the deposit.

Radiocarbon dating of burnt eggshells found in the lowest layers - thought to be evidence of human cooking - revealed them to be between 45,000 and 49,000 years old; analysis suggests they came from emus and a large, extinct flightless bird. Dating of quartz grains provided further evidence of the shelter’s age, with the lowest layers dated to around 44,000 years ago.

Among the finds within the lowest layers was the discovery of red ochre on a stone tool - the earliest evidence for the pigment’s use in Australia, possibly for body adornment - and a bone from a young Diprotodon optatum, thought to have been brought into the shelter by humans. “I think the jury is still out whether humans really hunted megafauna, but it is incredibly interesting,” said Hamm, adding that people might have hunted the young, as they were smaller. It is unclear if the bone was from a meal or intended for use as a tool.

A sharpened bone point,thought to date - in layers dating from between 40,000 and 38,000 years ago. Photograph: Giles Hamm

The discovery of the earliest examples of various tools - including a sharpened bone point thought to date from between 40,000 and 38,000 years ago - has also caused excitement, with many apparently more than 10,000 years older than similar artefacts found elsewhere in Australia.

Hamm told the ABC how he found the site with local Adnyamathanha elder Clifford Coulthard while surveying gorges in the northern Flinders Ranges.

“Nature called and Cliff walked up this creek bed into this gorge and found this amazing spring surrounded by rock art,” Hamm said.

“A man getting out of the car to go to the toilet led to the discovery of one of the most important sites in Australian pre-history.”

From the number of artefacts at each depth, the authors suggest the site was used infrequently from around 49,000 years ago, but saw a large increase in use around 40,000 years ago, and again around 18,000 years ago.

“Around 35 000 [years ago] we suddenly see again a decline in the use of the shelter,” said Hamm. “And we think that coincided with the onset of more arid conditions.”

“The site is really unique and it’s chock full of interesting stuff,” said John Alroy, a palaeobiologist at Macquarie University. The discoveries overturn arguments that people were unable to settle in the arid interior of Australia before megafauna were extinct and that humans did not have the means to hunt large animals, he added.

But Huw Barton, a bioarchaeologist from the University of Leicester has reservations. He suggests that the eggshells are not necessarily evidence of human activity, while small artefacts in the bottom layers might have trickled down from higher up - meaning humans might have first occupied the shelter nearer to 40,000 years ago, which would fit with evidence from other sites in the region.

Peter Hiscock, professor of Australian archaeology at the University of Sydney, also urged caution. “The dates are deeply anomalous and either they stem from an analytical problem or else they reveal a revolutionary shift in the chronology for ancient Australia,” he said. “Further scientific study must explore which is the most reasonable explanation.”