The debate over what killed off Australia’s giant animals during the last 100,000 years has been raging for over a century. Research presented this month at the biennial Conference on Australasian Vertebrate Evolution, Palaeontology and Systematics (CAVEPS) in Naracoorte, South Australia marked the beginning of a new approach to this question.

Australian “megafauna” included 2-meter-tall kangaroos, massive wombats, 2-ton bear-like marsupials, giant iguanas, ferocious “marsupial lions”, and huge flightless birds. Of the 57 megafauna species present during the Ice Age, only 15 survived extinction at that time. Africa is the only continent that has megafauna today; elsewhere they were extinct by the end of the Ice Age 12,000 years ago.
Climate change and large-scale human hunting are the two traditional theories put forward to account for this extinction.

A 2001 paper published in Science lent support to the human hunting theory, giving a date of around 46,000 years ago for the Australia-wide mass extinction, not long after humans supposedly arrived in Australia 50-60,000 years ago.

Archaeologists showed contrary evidence from a fossil site in NSW dated at 36,000 years old, which contains megafauna remains and human artifacts. Geochemical tests showed they were deposited together at the same time. The types of stone tools found were allegedly not hunting weapons, suggesting they may have only eaten meat on an opportunistic basis.

Other evidence suggests that most of the megafauna had already disappeared before the arrival of humans, with megafauna in Tasmania already extinct by the time humans arrived there 31,000 years ago.

The main argument against the climate change hypothesis is that Australia’s climate record shows no upset around 46,000 years ago, when most of the megafauna disappear from the fossil record.

The debate cannot be resolved until new techniques are applied to accurately place the last occurrences of megafauna and the arrival of humans in Australia, requiring further collaboration between the scientific disciplines.

Understanding the delicate balance between humans, animals and the ecosystem can help us conserve our wildlife better and prevent extinctions in the future.