Supercomputing is used to understand the shapes of otherwise-inscrutable processes, from the atomic-level movements of cells to thousand-year trends in the global climate. But supercomputing is also used to study human behavior, which is often just as inscrutable – especially as far back in the past as some researchers are looking. Recently, a team of scientists used a supercomputer from Sandia National Laboratories to learn how ancient humans likely traversed since-splintered supercontinents.
The supercontinent in question, called Sahul, eventually fractured into Australia, New Guinea and Tasmania. 50,000 to 70,000 years ago, humans ventured onto Sahul, but as Sandia National Laboratories archaeologist Devin White explained, researchers’ knowledge of human activities on Sahul past that point was quite limited – which, in turn, led to a lingering uncertainty vis-a-vis the earliest inhabitants of Australia. “One of the really big unanswered questions of prehistory is how Australia was populated in the distant past,” White said. “Scholars have debated it for at least 150 years.”
So the researchers employed one of the computers at Sandia – one typically used for autonomous systems and machine learning – to instead send a lone virtual woman on billions of journeys across the long-gone continent. Using a 500-meter resolution for the landmass and a pathing algorithm called “From Everywhere to Everywhere,” the researchers simulated a 25-year-old woman with 22 pounds of gear, food and water and sent her on her way, limiting her paths only through proximity to water and visible landmarks.
“We decided it would be really interesting to look at this question of human migration because the ways that we conceptualize a landscape should be relatively steady for a hiker in the 21st century and a person who was way-finding into a new region 70,000 years ago,” said Stefani Crabtree, the professor at Utah State University who led the study. “If it’s a new landscape and we don’t have a map, we’re going to want to know how to move efficiently throughout a space, where to find water, and where to camp — and we’ll orient ourselves based on high points around the lands.”
125 billion long walks later, the researchers had their answer: a network of “superhighways” criss-crossing the continent, along which early humans would have been able to walk without getting lost or dying of thirst.
“Australia’s not only the driest, but also the flattest populated continent on Earth,” said Sean Ulm, a professor of archaeology at James Cook University who 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.”
The researchers are hopeful that these results, while speaking to the distant past, could have newfound relevance as major crises like climate change begin to cause large-scale migrations – and could, of course, also be used to track similar migrations of ancient humans in other ancient supercontinents.