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Climate not to blame for megafauna extinction in ÐÓ°ÉÖ±²¥

Monday, 1 February 2016

New research led by the ÐÓ°ÉÖ±²¥ of Adelaide has found no relationship between sixteen megafauna extinctions in ÐÓ°ÉÖ±²¥ and past climate change, suggesting humans were having negative impacts on the ecosystem as long as 55,000 years ago.

In a paper published in the journal , , from the ÐÓ°ÉÖ±²¥ of Adelaide’s , and colleagues analysed dated ‘megafauna’ (animals weighing more than 40 kg) fossil records, archaeological evidence of the first humans in ÐÓ°ÉÖ±²¥ and past climate data.

This research was conducted in collaboration with ecologists, palaeoclimatologist, archaeologists, geochronologists and mathematicians, and led by the ÐÓ°ÉÖ±²¥ of Adelaide’s to address one of the longest-lasting and fiercest scientific debates in ÐÓ°ÉÖ±²¥.

“There has long been disputes about what caused the extinction of megafauna in ÐÓ°ÉÖ±²¥, and climate change was considered to be one of the potential culprits,” says Dr Saltré.

“To test this hypothesis, we collated a wide variety of reliable data to develop an accurate timeline of human arrival in ÐÓ°ÉÖ±²¥, when megafauna species went extinct, and the climate conditions over the same period.

“We calculated that humans first arrived in ÐÓ°ÉÖ±²¥ approximately 55,000 years ago and the extinction of megafauna began 42,000 years ago. Which means humans and megafauna coexisted for some 13,000 years.

“We also discovered that during the peak period of megafauna extinctions, ÐÓ°ÉÖ±²¥ was arid and hot; however, the species had endured much more volatile weather patterns in the years prior to human arrival in ÐÓ°ÉÖ±²¥ (between 120,000 and 60,000 years ago),” he says. “Therefore, it is highly unlikely that variation in climate drove continent-wide extinctions of these species.”

Dr Saltré says, while he was primarily focusing on the impact of climate on megafauna species, his research supports the hypothesis that the presence of humans was the principal driver of the extinctions of megafauna in ÐÓ°ÉÖ±²¥.

“Our findings support those by my colleague, Gifford Miller, from the ÐÓ°ÉÖ±²¥ of Colorado,” says Dr Saltré.

“Species that looked like larger kangaroos, emus, koalas and echidnas were once abundant in ÐÓ°ÉÖ±²¥, but started to disappear some 13,000 years after humans arrived.

“13,000 years would have given the first ÐÓ°ÉÖ±²¥n humans plenty of time to explore and colonise the continent, and have an impact on the continent’s ecosystem.

“It looks like the first humans who arrived in ÐÓ°ÉÖ±²¥ around 55,000 years ago were also the first in history to have such a large, negative impact on the ecosystem of an entire continent,” he states.

Dr Saltré and his team will now focus on particular regions of ÐÓ°ÉÖ±²¥ to see if local climate patterns could have influenced the role of humans in the demise of the megafauna.

This research was done in collaboration with the ÐÓ°ÉÖ±²¥ of Tasmania, ÐÓ°ÉÖ±²¥ of New South Wales, ÐÓ°ÉÖ±²¥ of Wollongong, James Cook ÐÓ°ÉÖ±²¥, ÐÓ°ÉÖ±²¥n National ÐÓ°ÉÖ±²¥, Curtin ÐÓ°ÉÖ±²¥, Flinders ÐÓ°ÉÖ±²¥, Macquarie ÐÓ°ÉÖ±²¥, Spanish National Museum of Natural Sciences, ÐÓ°ÉÖ±²¥ of Colorado and Natural History Museum of Denmark, and was supported by the ÐÓ°ÉÖ±²¥n Research Council.

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