The Australian Centre for Ancient DNA (ACAD) in South Australia led the study, which found that only after the climate warmed in Patagonia, at the bottom of South America, that megafauna began to die off about 12,300 years ago.
ACAD Director and Study leader Professor Alan Cooper said until now the cause of the extinction of megafauna had been a mystery.
“This is the first time we have been able to see anywhere in the world, climate change versus human hunting in an extinction event,” he said.
“Up until now people have either said it was climate change or human hunting and the two sides have been fighting fairly vociferously.
“The warming event seemed to do the damage but perhaps was only part of the equation. Human hunting on top of that seemed to then cause the extinction but by itself doesn’t do the job when the conditions are cold – it was the combination.”
The bones used in the study were from a Patagonian cave that was discovered in 1936 called Fell’s cave.
It was the first site in the world to show that humans had hunted Ice Age megafauna. The cave still contains dung specimens six to seven inches long from the giant ground sloth.
Other megafauna wiped out across Patagonia included the South American horse, giant jaguar and the enormous one-tonne short-faced bear.
Professor Cooper said in order to find out how the megafauna became extinct researchers looked at records for humans in the area that might be hunting them and compared it to the climate change in the region.
“Surprisingly humans had been in the area for about one to three thousand years before the point in which they (megafauna) all went extinct,” he said.
“When we contrasted that with the climate record what was quite obvious was that that period of time where nothing happened was a long cold period called the Antarctic Cold Reversal.
“As soon as that finished and it became warmer again the megafauna were all extinct within a couple hundred years.
“The warming changed vegetation patterns, produced a lot more water on the landscape and changed what the animals could live off. The assumption is the humans were still a key factor in the extinction.”
The only large species to survive were the ancestors of today’s llama and alpaca – the guanaco and vicuna.
The study was a collaboration between the University of Colorado Boulder, University of New South Wales, University of Magallanes in Patagonia and ACAD.
ACAD is part of the University of Adelaide’s School of Biological Sciences and specialises in the use of preserved genetic data from the environment such as ancient bones, fossils or bacteria to study evolution, climate change and genetics.
It is the largest centre of its kind in the Southern Hemisphere and the only institution that covers a broad range of DNA work in Australia.
Professor Cooper said having climate experts in nearby New South Wales made ACAD the only centre in the world that could have done this study.
“Chris Turney from the University of New South Wales is a carbon expert so he was the one that corrected all the carbon dates. Having that relationship with the University of New South Wales puts us in a unique position worldwide,” he said.
South Australia’s capital Adelaide has three long-standing public universities, Flinders University, University of South Australia, and the University of Adelaide, each of which are consistently rated highly in the international higher education rankings.Jump to next article