What we see now as Bass Strait—the waters that connect the Great Australian Bight to the Tasman Sea and divide mainland Australia from Lutruwita/Tasmania—was once a grassy plain. Tens of thousands of years ago huge volumes of the global oceans were frozen in sea ice and glaciers, making sea levels across Earth much lower and thus changing the face of continents we are now familiar with. Australia itself was 30% larger (some 2 million square kilometres) than it is today, connected to Lutruwita/Tasmania and New Guinea into a supercontinent we call “Sahul.”

In some recent research we examined how people moved across this larger connected landscape. We first looked to the underlying geophysical properties of the continent — the peaks, valleys, rivers, lakes, and other lumps and bumps of the terrain, the types of things that make up a topographical map. Then we imagined how people travelled across this landscape and used computer models to test our hypotheses. We think people navigated in new environments — much as people do today — by focusing on landmarks like hills, big rocks or mountains protruding above the relative flatness of the Australian continent.

People of the past navigated as people do today, by looking to prominent landmarks in their environment. Photograph by Rodney Campbell. CC BY-ND-NC 2.0.

But navigation using such prominent landscape features isn’t enough to tell us where the most commonly travelled routes were. For this we also need to think about other factors which directed where people wanted to walk, such as how people of different ages and abilities travel on foot, how difficult the landscape was to traverse, and the distribution of available freshwater sources in a largely arid continent.

In our work we programmed computer-generated people to navigate through a simulated ancient Australia. They looked to tall landscape features to find their way, stayed close to water, and moved in the typical ways humans adopt when on foot. This allowed us to map plausible routes people took to walk across Sahul.

People of Sahul needed to stay close to freshwater rivers, wetlands and waterholes when travelling through this largely arid continent. Photograph by Ed Dunens. CC BY 2.0.

We detected thousands of possible pathways, showing the unique ways that people moved throughout the continent after their first arrival about 70,000 years ago. Early people traversed and lived in all environments of Australia, ranging from the tropics to the arid zones. The rapid adaptation of people to all ecosystems is remarkable and one of the reasons for the success of people across the globe today.

Our map (pictured) shows the modelled routes thoughout Sahul. Areas of land are coloured green, and areas of water, the big inland lakes, are shaded light blue. Our computer simulations generated many diverse ways to cross Sahul, but there were some which stood out as the most common. These are the most likely ancient migration routes across the continent. The pathways look like threads on the landscape and the colour of the lines are linked to the likeliness of high levels of travel. The fainter the line is, the less commonly the route was used by our simulated people, like a rural highway. The brighter the line, the more it is like a freeway. Yellow lines indicate reasonably high use and orange and red lines highlight the most common routes – these are the ancient super highways.

The Bass Strait region is in the most southeasterly part of Sahul. It can be found at the bottom right of the map. Where the modern-day coastlines of Victoria and Lutruwita/Tasmania are separated by what is now the Bass Strait, our map shows a continuous land connection which existed when sea-levels were lower, around 70,000 to about 20,000 years ago.

Our model predicts a very prominent path, a red line highway, that skirts a large freshwater lake (Lake Bass) and links what is now northeastern Lutruwita/Tasmania to the heart of Victoria. This red line connects to other red continental superhighways in north and west central Sahul, which were the primary movement routes leading to the rest of ancient Australia. The grassy plain of the Bass Strait formed part of a web of connection across this vast continent.

Generations ago, people lived on Bass Strait. They also moved across it for all of the reasons that people move today—to look after Country, to have meetings, to visit with friends and family, to hunt, and just to explore. We know that people moved across this area because that’s how First Nations people got to Lutruwita/Tasmania in the first place, and because of the ways cultures connect on both sides of the strait. As rising sea-levels began inundating Bass Strait over the past 15,000 years, landscapes that people lived on and loved became submerged, and new ways of life emerged as people on either side with deep connections to Country were separated.

High points which once marked the former Bass Strait superhighway are still visible above the waves in Tayaritja/the Furneaux Group of Islands. Photograph by Simon Haberle. CC BY-NC-ND 4.0.