This image shows a close-up view of a cut kangaroo bone and a microCT image of the cut surfaces.
Credit: Archer et al. 2025
The world was a much stranger place before
Based on the available archaeological evidence, it appears that humans first set foot in Australia sometime around 65,000 years ago. At that time, the continent was home to many bizarre, giant marsupials, as well as flightless birds, even larger and more fearsome than today's emus and cassowaries. For the next 20,000 years, Australia's first peoples shared the landscape with short-faced kangaroos; Zygomaturus trilobusa hulking 500-kilogram marsupial that looks a bit like a rhinoceros; And Diprotodon choosesthe largest marsupial to ever live: a 3,000-pound monster that roamed in huge herds (imagine a bison-sized bear with a marmot's face).
These species became extinct some 45–40,000 years ago; today they live on in ancient cave paintings and stories, some of which seem to describe people interacting with now-extinct species.
Since they had shared the continent with humans for at least 20,000 years at this point, it does not appear that the sudden arrival of humans caused an immediate mass extinction. But it's possible that by hunting or even setting controlled fires, humans have put enough stress on these megafauna species to make them vulnerable enough to the next climate shock that will finish them off.
In some parts of the world there is direct evidence that Pleistocene people hunted or obtained meat from the remains of now-extinct megafauna. Elsewhere, archaeologists are still debating whether it was humans, the inexorable end of the last Ice Age, or some combination of the two that killed off the Ice Age's greatest giants. The interactions between people and their local ecosystems looked (and still look) different everywhere, depending on culture, environment, and a variety of other factors.
