A new study published in the journal Archaeology in Oceania has reopened a long-standing debate about when people migrated to Australia, suggesting a later arrival that overturns decades of archaeological evidence. The research, by archaeologists Jim Allen of La Trobe University and James O’Connell of the University of Utah, argues that Homo sapiens would not have reached Australia before 50,000 years ago — a stance taken largely in light of recent finds of ancient DNA.

A group of Indigenous Australians. Credit: Steve Evans / CC BY 2.0

The crux of Allen and O’Connell’s argument is that all modern non-African humans, including Indigenous Australians, carry Neanderthal DNA. Two new genetic studies have concluded that Neanderthals and modern humans only interbred once, somewhere between 50,500 and 43,500 years ago in Eurasia. Therefore, the researchers conclude that any human population that made it to Australia must have arrived sometime after this interbreeding event.

According to the researchers, evidence of early Sahul colonization is largely in line with this genetic timeline. Most known archaeological sites in Sahul indicate human presence between 43,000 and 54,000 years ago.

But this DNA model contradicts an archaeological report from the Madjedbebe rock shelter in northern Australia, where stone tools and ochre “crayons” were dated in 2017 to at least 65,000 years ago. That study is one of the most important contributions to the evidence for ancient people in Australia. However, the dating is questionable due to the sandy conditions of the site, which could have shifted older sediment layers over the years, making the artifacts appear older than they really are.

Aboriginal rock art at Ubirr Art Site, Kakadu National Park, Northern Territory, Australia. Credit: Tourism NT

A number of experts remain skeptical of the new hypothesis, particularly its excessive reliance on genetic information. Others argue that data from neighboring Southeast Asia supports the possibility of an earlier migration into Sahul. For instance, rock art in Sulawesi, Indonesia, has been reliably dated back to at least 51,200 years ago. They suggest that those artists may have belonged to the same cultural group that originally colonized Sahul, perhaps as early as 65,000 years ago.

Another point of contention relates to the broader implication of the “Paleolithic Revolution” — a hypothesized burst of complex human behavior such as seafaring, tool making, and symbolic art that Allen and O’Connell believe occurred simultaneously with the dispersal of Homo sapiens from Africa roughly 50,000 years ago. This theory has also been subject to criticism, though.

Despite the robust genetic evidence for a more recent Australian arrival, the archaeological record — the most significant being the evidence from Madjedbebe — continues to raise doubts about a strict 50,000-year timeline. The inconsistency between the genetic and archaeological narratives has made it increasingly clear that neither line of evidence is yet definitive.

Ultimately, this new debate underscores the complexity of reconstructing human history. As researchers pursue both genetic and archaeological avenues, interdisciplinary collaboration will be essential to untangle the history of Australia’s first inhabitants.

More information: Allen, J., & O’Connell, J. F. (2025). Recent DNA Studies Question a 65 kya Arrival of Humans in Sahul. Archaeology in Oceania. doi:10.1002/arco.70002