The best path across the desert is rarely the straightest. For the first human inhabitants of Sahul — the super-continent that underlies modern Australia and New Guinea — camping at the next spring, stream, or rock shelter allowed them to thrive for hundreds of generations. Those who successfully traversed the landmarks made their way across the continent, spreading from their landfall in the Northwest across the continent, making their way to all corners of Australia and New Guinea.
An international team of archaeologists, geographers, ecologists, and computer scientists has mapped the probable “superhighways” that led to the first peopling of the Australian continent some 50,000-70,000 years ago.
Their study, published in Nature Human Behaviour, is the largest reconstruction of a network of human migration paths into a new landscape. It is also the first to apply rigorous computational analysis at the continental scale, testing 125 billion possible pathways.
“One of the really big unanswered questions of prehistory is how Australia was populated in the distant past. Scholars have debated it for at least a hundred and fifty years,” says Devin White, an archaeologist and remote sensing scientist at Sandia National Laboratories. “It is the largest and most complex project of its kind that I’d ever been asked to take on.”
To re-create the migrations across Sahul, the researchers first needed to simulate the topography of the supercontinent. They “drained” the oceans that now separate mainland Australia from New Guinea and Tasmania. Then, using hydrological and paleo-geographical data, they reconstructed inland lakes, major rivers, promontory rocks, and mountain ranges that would have attracted the gaze of a wandering human.
Next, the researchers programmed in-silico stand-ins for the human travelers. The team adapted an algorithm called “From Everywhere to Everywhere,” created by White, to program the way-finders based on the caloric needs of a 25-year-old female carrying 10 kg of water and tools.
Giving the virtual travellers a goal of staying alive they crossed the continent in search of freshwater.
Sean Ulm, an archaeologist and Distinguished Professor at James Cook University, explained:
“Australia’s not only the driest, but it’s also the flattest populated continent on Earth,”
Ulm is also Deputy Director of the Australian Research Council Centre of Excellence for Australian Biodiversity and Heritage (CABAH), whose researchers contributed to the project.
“Our research shows that prominent landscape features and water sources were critical for people to navigate and survive on the continent. In many Aboriginal societies, landscape features are known to have been created by ancestral beings during the Dreaming.
“Every ridgeline, hill, river, beach and water source is named, storied and inscribed into the very fabric of societies, emphasising the intimate relationship between people and place. The landscape is literally woven into peoples’ lives and their histories. It seems that these relationships between people and Country probably date back to the earliest peopling of the continent.”
The results suggest that there are fundamental rules humans follow as they move into new landscapes and that the researchers’ approach could shed light on other major migrations in human history, such as the first waves of migration out of Africa at least 120,000 years ago.
Future work, Stefani Crabtree (Santa Fe Institute, Utah State University, CABAH) says, could inform the search for undiscovered archaeological sites, or even apply the techniques to forecast the movements of human migration in the near future, as populations flee drowning coastlines and climate disruptions.
CABAH is an ARC Centre of Excellence that brings together expertise from diverse academic disciplines to answer fundamental questions about the natural and human history of the region, including how and when people first came to Australia.