Ancient Australia’s super-sized animals, the megafauna, became extinct about 42,000 years ago, but the role of humans in their demise has been debated for decades. New research challenges the notion built from previous studies that our species was the principal driver of extinctions in Australia, and that climate change was at best a secondary contributor; instead, it reveals a more complex scenario where climate change could have limited the amount of available resources for giant animals, but that human appearance was likely another important and necessary contributor to explain the megafauna’s disappearance in many parts of the continent.
“There has been much debate among scientists about what conditions led to this extinction event,” said Dr. Frédérik Saltré, a researcher at Flinders University.
“Resolving this question is important because it is one of the oldest such extinction events anywhere after modern human beings evolved and left Africa.”
In the study, Dr. Saltré and colleagues analyzed fossil data, climate reconstructions, and archaeological information describing patterns in human migration across south-eastern Australia.
They developed and applied sophisticated mathematical models to test scenarios to explain regional variation in the periods during which people and megafauna coexisted.
They found that the extinction pattern could only be explained by the combination of people sharing the environment and the reduced of availability of freshwater due to climate change.
“The regional patterns in extinction are best explained by the hypothesis that people migrated across Australia, exploiting lakes and other sources of drinking water connecting the drier regions in between,” said Flinders University’s Professor Corey Bradshaw.
“It is plausible that megafauna species were attracted to the same freshwater sources as humans, thus increasing the chance of interactions.”
“The new insight that human pressure and climate change work together to trigger species extinction is a ‘stark warning’ for the immediate future of the planet’s biodiversity facing even stronger climate and habitat disruption,” Dr. Saltré said.
The findings are published in the journal Nature Communications.
F. Saltré et al. 2019. Climate-human interaction associated with southeast Australian megafauna extinction patterns. Nat Commun 10, 5311; doi: 10.1038/s41467-019-13277-0