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No evidence for human megafauna wipeout: study
By Bob Beale
August 12, 2008

No evidence supports claims that human activity resulted in more than 60 species of Australia's large prehistoric animals - or megafauna - being rapidly wiped out in a brief "extinction window" between 40,000 and 50,000 years ago, according to a new study.

A review of the available evidence indicates that only 13 species of megafauna were still alive when humans first arrived in Australia and that those people did not focus on big-game hunting nor cause major habitat change by widespread use of fire.

The review counters earlier claims that the so-called terminal extinction date was about 46,400 years ago, a timing argued to be broadly coincident with estimates of first colonization of the continent by modern humans, say researchers Judith Field, from the University of Sydney, and Steve Wroe, from the University of New South Wales. Their findings are published in the journal Earth Sciences Review.

They note that considerable evidence exists to suggest that in some parts of the continent, people and some species of megafauna may have co-existed for some thousands of years.

"Over 60 animal species disappeared from the Australian continent during that time, mostly large to gigantic marsupials, birds and reptiles," they note.

"At the present time there is no substantive argument for a terminal extinction date of 46.4 kyr, the current evidence indicating that there is no specific time period that correlates to any single mass extinction event.

"On the basis of available evidence arguments for either human or climatic causation are entirely circumstantial and implicitly require acceptance of many unproven assumptions."

The 13 species that remained in existence around the time of human arrival included a giant flightless bird called Genyornis newtoni, a three-tonne marsupial browser called Diprotodon optatum and a number of short-faced and heavily built kangaroos and giant wallabies. At least two species of crocodiles and one giant goanna called Megalania also disappeared.

"The elimination of the purported 'extinction window' opens up the debate to the possibility that other large-scale processes may have been important factors in the extinction process," says Dr Wroe. "This represents a significant shift in our approach to the study of this event and consideration of climate and environmental change must be factored into our studies.

"Any claim for a human role on the extinction process must demonstrate, at the minimum, an association of humans and these now extinct animals. Only one site on the continent can do that - Cuddie Springs in northern New South Wales. Nowhere else has this association been found.

"It is not enough to argue for a lack of evidence for climate change to then put humans at the scene, with no supporting evidence. Any arguments for a human role has to move beyond associations inferred by overlapping dates for occupation and megafauna persistence from distant and separate localities."

 

Media contact:

UNSW Faculty of Science, Bob Beale: 0411 705 435