Humans first came to Australia 10,000 – 20,000 years earlier than previously thought

The results set a new timeline for the dispersal of modern humans out of Africa and across south Asia.

The date when humans first came to Australia is contested, with estimates ranging anywhere from 47,000 to 60,000 years ago. One of the reasons behind this contention comes from artifact dating concerns at Australia’s oldest known human occupation site, a rock shelter in northern Australia called Madjedbebe. In a new Nature study, researchers went back to the site and used advanced dating techniques to push back estimates of how long Australia has been inhabited by humans to 65,000 years.

We spoke to one of the authors, Chris Clarkson of the University of Queensland, about the study.

ResearchGate: What motivated this study?

Chris Clarkson: There has been a lot of controversy about the timing of first colonization of Australia, and this has big implications for the Out of Africa story and the colonization of southeast Asia as well as the maritime gateway to Australia and New Guinea. The original dating of the site at 50,000 years with thermoluminescence in 1990—making this Australia's oldest site at the time—left a lot of archaeologists wondering about the site and dating technique, but no further publications or work was completed on the site, and the artefacts were still sitting in the museum largely unanalyzed. I wasn't happy with the situation, and 25 years seemed too long to sit languishing in a dusty museum. I gathered some top archaeologists with different specialties together and we went to the Aboriginal community and explained the importance of the site and why further work was needed. They gave us permission to re-excavate, and with funding from the Australian Research Committee, we were off.

Team leader Chris Clarkson with Richard Fullagar and Elspeth Hayes examining a rare grindstone from the lowest layers of the excavation. Picture by Dominic O'Brien. Copyright Gundjeihmi Aboriginal Corporation 2015.

RG: Can you tell us what you found?

Clarkson: We found a site of truly stunning richness, teeming with stone artefacts of all kinds, ground ochre pigments, slabs of stone with reflective paint on them, the oldest grindstones in Australia and the oldest edge-ground axes in the world. Most astounding of all was that new dates of 65,000 years from the base of the site confirmed that this is Australia's oldest known site, pushing back ages for first colonization by another 10-20,000 years. We believe there are many such sites in the amazing Kakadu landscape and efforts must be renewed to protect these sites and to appreciate them as places of global significance.

Excavation leader Chris Clarkson stands in front of the 2015 excavation area with local Djurrubu Aboriginal Rangers Vernon Hardy, Mitchum Nango, Jacob Baird, and Claude Hardy. Picture by Dominic O'Brien. Copyright Gundjeihmi Aboriginal Corporation 2015.

RG: How did you make this discovery?

Clarkson: We excavated a large area against the back wall of the shelter and dug down painstakingly to around three meters depth. We recorded all the artefacts in 3-D with a laser total station and got a really good understanding of site structure and how it formed. Then we took pieces of charcoal from ancient fireplaces and dated these with radiocarbon dating, and many sand grains from the walls and dated these with Optically Stimulated Luminescence, giving us ages of 65,000 years for the oldest occupation layers.

RG: Where did these humans come from? And how did they get to Australia?

Clarkson: All modern humans like ourselves originally come from Africa, where we evolved 2-300,000 years ago. Our species migrated out of Africa and colonized the rest of the world, but it has always been difficult to determine precisely when this happened. Australia was an early step in this out of Africa migration involving many sea crossings of up to 90km each. The ages we now have for the colonization of Australia mean that modern humans must have left Africa before 65,000 years ago, and that now provides us with a fantastic minimum age for the early spread out of Africa.

RG: What was life like for the people that first arrived in Australia? What type of technology did they have access to?

Clarkson: We've found traces of the earliest colonist's lifestyles at the site. They were eating many of the same plant foods as today—nuts, yams, seeds, and fruit—and we have some of the technologies used to gather and process these foods, like grinding stones and edge ground axes. We also have the stone tools used to cut and process foods and make wooden tools. These early colonists were also engaged in artistic behaviors, as seen from kilograms of ground ochre found in the lowest layer, along with abundant traces of tiny fragments of reflective mica which we interpret as meaning they were mixing reflective paints.

Edge-ground hatchet head being excavated. Picture by Chris Clarkson. Copyright Gundjeihmi Aboriginal Corporation 2015.

RG: Do you think the arrival of humans could have played a role in the extinction of Australian Megafauna?

Clarkson: Pushing back the age of first occupation by another 10, 000 - 20,000 years means that human overlap with the megafauna was very long indeed. This casts serious doubt on any claims that Aborigines quickly drove the megafauna to extinction, and it is more likely that climate change and extreme drying and cooling coming into the last Glacial Maximum was the ultimate cause of their demise, though humans may well have preyed on them as well.

Featured image of Madjedbebe site with excavation in progress. By Dominic O'Brien. Copyright Gundjeihmi Aboriginal Corporation 2015.