Australia wouldn't have been an easy continent to migrate to. It's an island continent, so any visitors would need to have arrived by sea, and it's a long way from where humans first evolved in Africa. Getting to Australia would have required some remarkable ingenuity, so when scientists first found evidence that humans had arrived on the continent as long ago as 60,000 years, it was surprising. By contrast, there's scant evidence that humans began populating the Americas until about 15,000 years ago.

But now archaeologists have uncovered new evidence that could push the date of human habitation in Australia back even further, possibly as far as 80,000 years ago. It's a mind-boggling discovery that could forever alter the timeline of human migration around the world, reports The Guardian.

The findings involve a huge swathe of artifacts, about 11,000 of them, unearthed from Kakadu National Park in Australia's Northern Territory.

“People got here much earlier than we thought, which means of course they must also have left Africa much earlier to have traveled on their long journey through Asia and southeast Asia to Australia,” said the lead author, associate professor Chris Clarkson from the University of Queensland. “It also means the time of overlap with the megafauna, for instance, is much longer than originally thought — maybe as much as 20,000 or 25,000 years. It puts to rest the idea that Aboriginal people wiped out the megafauna very quickly.”

Australia used to host some gargantuan megafauna, large animals like massive diprotodons or marsupial lions. Since many of these megafauna went extinct around the same time that humans were believed to have arrived, theorists have assumed that humans wiped them out. But those theories could be called into doubt if humans actually arrived much earlier.

The discovery also bolsters oral histories passed down through Australian aboriginal cultures for millennia. Many of these histories suggest that people have lived in Australia for much longer than scientists have previously believed.

Artifacts collected as part of this study include ochre and reflective paint substances, as well as the oldest unbroken ground-edge stone axes in the world, by about 20,000 years, and the oldest known seed-grinding tools in Australia. Although there was some evidence that the artifacts could have shifted around over the years, dating methods gave a 95 percent chance that the uncovered artifacts were older than 70,000 years.

The research was published in the journal Nature.