Signs of earliest human habitation in Australia

People began to venture into Australia’s arid interior around 49,000 years ago – 10,000 years earlier than previously thought – according to evidence from a new excavation in South Australia.

The recently discovered rock shelter in the northern Flinders Ranges also shows signs that these earliest outback explorers interacted with now-extinct giant animals and developed key technologies far earlier than was believed.

The findings were unveiled in Nature.

Exactly when the first humans arrived in Australia is disputed, and dogged by controversy over dating techniques, but it is generally agreed that people were established on the continent by 50,000 years ago.

Arriving somewhere along the north coast, they are known to have explored around Australia’s coastline. But until now there was no evidence that the early settlers ventured into Australia’s arid interior.

Warratyi, a small rock shelter situated 550 kilometres north of Adelaide, has changed all that.

“It is an exciting find, though in many ways it is surprising we’ve never found arid interior shelters like Warratyi before, as the climate was relatively good when the first people arrived, and interior lakes and rivers were in good nick,” says Richard Roberts from the University of Wollongong, who wasn’t involved in this study but has worked on some of Australia’s oldest human occupied sites.

Perched high above an old stream bed and a good few hours drive from any modern settlement, the remote shelter was excavated by Giles Hamm from La Trobe University in Melbourne and colleagues during 2012 and 2013.

From two small trenches dug into the metre or so of hard-packed sediment inside the shelter, the team extracted more than 4,300 artefacts. The oldest of these included burned eggshell from emu and the now-extinct giant flightless bird Genyornis newtoni, which was carbon dated to 49,000 years.

Sediments from the site were dated using single-grain optically stimulated luminescence to around 44,000 years ago. A thigh-bone from the rhino-like Diprotodon optatum (which became extinct around 44,000 years ago) was also found at this lowest level. 

“The Diprotodon bone is a remarkable find, and given its location – high up in a narrow rock shelter,” says Chris Clarkson, an archaeologist at the University of Queensland in Brisbane, who wasn’t involved with the study.

“It wouldn’t have arrived by chance and shows a likely human association with the megafauna.”

The Diprotodon optatum was a giant megafauna herbivore, weighing around three tonnes and measuring four metres long. Credit: Peter Murray

Travelling up in time through the sediment layers, the artefacts reveal that the shelter was regularly used and that these people were innovative, culturally sophisticated and quick to adapt to their environment.

A bone point dated to 38,000 years old suggests that these people were using bone for working animal hides a full 10,000 years earlier than previously reported in Australia.

Similarly, the discovery of plant resin on the edge of stone tools dating 38,000 years suggests the hafting of tools onto wooden handles more than 10,000 years earlier than previously shown for Australia.

Meanwhile, red ochre recovered from the earliest levels of the shelter and white gypsum pigment dating to 40,000 years ago was most likely used for body art. This suggests that rich cultural traditions and rituals were an important part of life from the earliest days. 

By 35,000 years ago, the climate became drier and colder as the Earth was gripped in a glacial phase. For the people living in the Warratyi region, life would have become harder as water sources dried up, vegetation dwindled and the previously abundant sources of game diminished.

But the discovery of “backed” microliths (small blades with one edge blunted to allow stronger hafting) dating to 30,000 years ago – 10,000 years earlier than previously recorded in Australia – suggest that the Warratyi people adapted to the new challenges.

“By 24,000 years ago it would have been a really tough to live in the arid zone, so it is fascinating to see these multifunctional and lightweight tools emerge, perhaps enabling them to adapt their hunting techniques and move around more,” Clarkson says.

The most plausible migration route for the first visitors to Warratyi would be along the river corridors from the north, avoiding the eastern Simpson desert.

If that occurred 50,000 years ago, it also seems reasonable for other pioneering groups of people to have splintered off this northern migration route – maybe to follow the Willandra lakes system and perhaps explaining how Australia’s oldest human remains (40,000 years old) ended up at Lake Mungo, 700 kilometres south-east of Warratyi.

As analysis of Warratyi’s rich deposits continues, the finds are likely to re-write the history of Australia’s earliest settlers.

“We’ve excavated less than one-fifth of the Warratyi sediment so far, and already it has thrown open the debate about how and when Australia’s interior was colonised,” Hamm says.