Paleo-archaeologists are beginning to iron out the timeline of human habitation in Australia. Last year, using new techniques to date human artifacts, researchers confirmed a theory first proposed in the late 1980s that Homo sapiens had made it to the island continent more than 50,000 years ago. Now, as April Reese at Science reports, researchers are finding that those early inhabitants, who are now theorized to have begun colonizing Australia at least 65,000 years ago, made it to the continent’s brutal Western Desert only several thousand years after their arrival.
The new artifacts were found in a small sandstone cave called Karnatukul (Serpent’s Glen) Rock Shelter in the Little Sandy Desert, a subregion of the Western Desert. Over the years, paleo-archaeologists have recovered 25,000 objects from the shelter including stone tools, human figures and rock paintings spanning tens of thousands of years of occupation. More recently, archaeologists began excavating the floor of the cave. Under a layer of sandstone rock that had fallen from the ceiling, a team led by archaeologists Peter Veth and Jo McDonald of The University of Western Australia in Perth discovered a crescent-shaped stone tool, which may have been a spear part or was used to carve wood. Radio-carbon dating of charcoal in the surrounding sediment layer showed the artifact was 43,000 years old, about 10,000 years older than previously dated artifacts in the region. An iron scraper was also found on the floor that the team dated to about 47,000 years ago. The finds are detailed in the journal PLoS One.
The stone artifact is of particular interest to researchers because it shows signs that it was hafted, or had a handle attached. Microscopic examination reveals evidence of resins used to help hold the stone blade in place, which rewrites the history of tool use on the continent. “This is more than 15,000 years earlier than other known Australian examples of this tool type,” McDonald says in a press release, noting that similar tools have been found in southern and eastern Australia, but “most date to the last 4,000 years.”
Writing over at The Conversation, McDonald and Veth explain these types of stone tools became more common as the climate of the continent changed due to El Niño–southern oscillation events that occurred 4,000 to 5,000 years ago. But their appearance so long ago and so deep in the desert is evidence that the earliest inhabitants of Australia had some skill when it came to exploring and living in new environments. “These current findings support the notion that the First Australians adapted with ingenuity and flexibility as they quickly dispersed into every bioregion across the country,” they write.
Rachel Wood, a radiocarbon dating expert at the Australian National University, tells Reese of Science that there are some factors that could make the dates inexact. First, the charcoal in the sediment isn’t necessarily manmade and could be from natural sources, meaning the tools and charcoal are not directly related. There’s also the possibility that the tools have shifted over the millennia moving from layer to layer. But she does agree that the tools are at least 45,000 years old.
Ongoing research may unearth new artifacts to further confirm these dates or push them back even further. Seeing as carbon-dating technology only reliably reaches about 50,000 years into history, it will require other techniques, like thermoluminescence dating to see that far into the past.