The Giant Kangaroo's Extinction Is More Depressing Than We Thought

During the late Pleistocene epoch, which took place between 126,000 and 11,700 years ago, hordes of megafauna species – large organisms that weigh roughly 110 pounds or more – died out in what is known as the megafaunal extinctions. Indeed, due to the massive changes that occurred during the late Pleistocene, many animals that lived during that epoch did not survive into the succeeding Holocene epoch.

Different continents experienced these extinctions at varying times and scales. In North America, extinctions began roughly 12,900 years ago, with large mammals like woolly mammoths and saber-toothed cats going extinct by the end of the Pleistocene. In Australia, more than 90% of the continent's large animal species went extinct between 65,000 and 40,000 years ago, and more than half of those heavyweight animal species were kangaroos, including Procoptodon goliah, a giant that may have stood over 6 feet tall and weighed over 440 pounds.

The cause of kangaroo extinction is a hotly debated topic, and one which is likely to remain hotly debated for some time. Part of the issue with arriving at an answer is a lack of evidence from that period, but for the most part, researchers suspect changes in the climate and the resulting reduction in dietary options were to blame, alongside the arrival of human hunters. Now, however, a new study has taken a closer look at hundreds of kangaroo teeth, both ancient and modern, and concluded that human beings had a lot more to do with the extinction of Australia's kangaroos than previously thought.

Today, Australia is home to four species of kangaroo, which is one of several animals with a pouch. The red kangaroo, eastern grey kangaroo, western grey kangaroo, and the antilopine kangaroo all reside on the continent in our modern age. However, there were once many more species of kangaroo, most of which died out in the late Pleistocene extinctions. Climate has typically been blamed for this reduction of kangaroo numbers, but the impact of human hunters, who arrived on the continent between 70,000 and 50,000 years ago, has always been factored into that explanation. A report from January 2025, published in Science, has now upended that view, showing that kangaroos had weathered major climatic shifts before and suggesting human hunters had much more of an impact on these species than previously thought.

The study details the analysis of the teeth of 937 kangaroos, both fossilized and modern. Led by paleontologist Samuel Arman of the Museum and Art Gallery of the Northern Territory in Alice Springs, Australia, the team of researchers studied the teeth specimens for signs of wear in order to gain an understanding of the kangaroos' diets. While previous studies looked at fossilized skulls and jaws and determined that kangaroos ate only tough plants instead of grasses, Arman's study found that the animals had a much more varied diet than previously thought, suggesting they were more than capable of surviving dramatic changes in climate.

Included in the study were the teeth of 12 ancient and 16 modern species — a varied sampling that led to the identification of the extinct kangaroos as generalist eaters, capable of adapting when the climate changed in the late Pleistocene and certain types of vegetation were wiped out. 

Recent research indicates that, due to the newly-identified generalist diet of the kangaroos during the Pleistocene era, their widespread extinction was much more likely to have been the result of human hunters than climate change. This explanation also dovetails with how well the kangaroo adapted to the shifting climate of Australia in earlier periods. During the Miocene Epoch, which took place between roughly 23 million and 5 million years ago, Earth's climate underwent marked changes which caused Australia to transform from a lush rainforest into a drier landscape populated by shrubs and grasses. During this shift, kangaroos continued to thrive, with new species even cropping up.

Furthermore, a 2010 study on the late Pleistocene extinctions, published in PNAS, similarly concluded that the arrival of humans was likely decisive in southwestern Australian extinctions, although the researchers did note that changes in climate and fire activity could have contributed. Not all scientists are in agreement, though. Larisa DeSantis, a paleontologist at Vanderbilt University who wasn't involved with the study, told NPR, "I think looking at one spot in time is not enough to discount the role that climate may play in previous extinctions."