Last updated November 29, 2019 at 3:57 pm
The shift and loss of suitable habitats by a changing climate played a key role in the fate of Australian megafauna, with human hunting being an additional stress.
Why This Matters: The past sends a stark warning about our role in future extinctions.
Megafauna, giant beasts that once roamed the continent — including wombat-like creatures as big as cars, birds more than two metres tall, and lizards more than seven metres long — became extinct about 42,000 years ago. But the role of people in their demise has been hotly debated for decades.
A new study, led by a team of researchers from the Centre of Excellence for Australian Biodiversity and Heritage (CABAH), analysed fossil data, climate reconstructions, and archaeological information describing patterns in human migration across south-eastern Australia.
Humans and climate sealed the fate of megafauna
The results suggest it was a combination of climate change and the impact of people that sealed the fate of megafauna, at least in south-eastern Australia.
“Resolving this question is important because it is one of the oldest such extinction events anywhere after modern human beings evolved and left Africa”, he adds.
The researchers suggest that modern humans weren’t a ‘super predator’.
Instead, they suggest that it’s likely humans were an additional stressor to climate shifts, impacting megafauna’s ability to recover from these climate-related problems.
The findings are the result of analysis and complex modelling based on data including more than 10,000 fossils and archaeological records. The team developed and applied sophisticated mathematical models to the data to test scenarios to explain regional variation in the periods during which people and megafauna coexisted.
A stark warning for the immediate future
Using fossil data and archaeological evidence of human activity, the researchers were able to map regional patterns of megafauna extinction.
They developed sophisticated models to test the impact of factors including climate, water availability, and human activity on localised patterns of megafauna extinction.
The distribution of freshwater — a precious commodity for animals and people alike as the climate warmed — can explain regional differences in the timing at which megafauna died out.
“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,” says co-investigator Corey Bradshaw from Flinders University.
“It is plausible that megafauna species were attracted to the same freshwater sources as were 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, Saltré concludes.