The cause of extinction has long been a contentious question with either human impact or climatic change the mechanism ascribed, but critical new evidence published in Nature Communications shows that humans were far more likely the culprit.
“Whether humans were responsible for the demise of the Pleistocene megafauna across Australia has been debated for many years,” said lead author palaeoecologist Dr Sander van der Kaars from the Monash School of Earth, Atmosphere and Environment.
“Our study found that the demise of the megafauna in southwest Australia took place from 45,000 to 43,100 years ago and was not linked to major changes in climate, vegetation or biomass burning but is consistent with extinction being driven by ‘imperceptible overkill’ by humans,” he said.
The research team analysed a continuous and precisely dated sediment core collected offshore southwest Australia that captures the last 150,000 years in high resolution.
Environmental proxies preserved in the sediments track environmental change and the abundance of megafauna.
The researchers found that the major environmental shifts of the last glacial cycle had little impact on the abundance of megafauna, as recorded by the dung fungus Sporormiella, and megafaunal extinction commenced within 2000 years of humans colonising Australia and took less than 2000 years to complete.
The regional nature and scale of the changes captured in the marine core bolsters the validity of their reconstructions relative to site-specific terrestrial sediment core studies.
“The results of this study are of significant interest across the archaeological and earth science communities, and to the general public who remain fascinated by the menagerie of now extinct giant animals that roamed the planet, and the cause of their extinction, as our own species began its persistent colonisation of Earth,” Dr van der Kaars said.
Source: Monash University