The timeline and means by which ancient humans made their way to what is now Australia and New Guinea have sparked much debate over the years. Recent genetic studies indicate this event likely occurred at least 60,000 years ago and involved two separate routes.

The regions of modern-day Australia, Tasmania, and New Guinea were once part of Sahul, an ancient continent that emerged during the peak of the ice age when sea levels were significantly lower. Researchers have been keen to understand human migration into these regions as it necessitated navigating dangerous ocean stretches of over 100 kilometers, even during low sea levels.

There are two primary theories regarding the arrival of humans in Sahul: one suggests it took place at least 60,000 years ago, while the other posits a timeline of around 45,000 years ago.

Regarding the approach taken, scientists have put forth two main routes. The southern route is believed to have led to Australia by sea from present-day mainland Southeast Asia through the Sunda region that comprises Malaysia, Indonesia, and Timor. The northern route, however, has more compelling supporting evidence, indicating that humans migrated through the Philippines and Sulawesi to reach modern-day New Guinea, where ancient hominin stone tools dating back millions of years were recently found.

To unravel these migrations, Martin Richards and his colleagues from the University of Huddersfield in the UK examined approximately 2,500 genome sequences from Indigenous Australians, Papua New Guineans, and various populations across the Western Pacific and Southeast Asia.

By analyzing DNA mutation rates and the genetic ties between these populations, the researchers determined that the initial human settlement of Sahul occurred via both routes, but predominantly through the northern pathway.

The question of timing has also been addressed by the researchers. “We traced both dispersals to around the same period, approximately 60,000 years ago,” Richards noted. “This lends support to the ‘long chronology’ of settlement as opposed to the ‘short chronology’ suggesting arrival around 45,000 to 50,000 years ago.”

The findings further illustrate that migration wasn’t a straightforward process, partially based on the discovery of ancient genetic lineages in a 1,700-year-old burial site in Sulawesi. The team also detected evidence indicating that shortly after their arrival on Sahul, coastal and marine communities began migrating towards what we now refer to as the Solomon Islands.

Adam Blum, a professor at Griffith University in Brisbane, asserted that the field of paleogenetics, which investigates history through preserved genetic materials, “seems to adjust the narrative with each new study.”

“We believe this research bolsters the idea that the northern route played a crucial role in the early populating of Australia,” Blum remarked. “Considering the ancient cave art found on Sulawesi, the possibility is rapidly becoming more plausible.”

This remarkable rock artwork has been dated to at least 51,200 years ago, Blum explained. “I have a strong suspicion that individuals were crafting art in Sulawesi’s caves and shelters over 65,000 years ago.”

Peter Veth and his team at the University of Western Australia in Perth assert that even the most conservative estimates from the Majedbebe site in Australia’s Northern Territory suggest human activity traces exceeding 60,000 years. New research further underscores the significance of early human arrival in Sahul.

Discovery Tour: Archaeology and Paleontology

New Scientist frequently features incredible archaeological sites that have transformed our understanding of human history and the dawn of civilization. Why not explore them yourself?