Artist's reconstruction of a marsupial lion -- Thylacoleo carnifex. (Credit: Peter Schouten)
May 6, 2013 — Most species
of gigantic animals that once roamed Australia had disappeared by the
time people arrived, a major review of the available evidence has
concluded.
The research challenges the claim that humans were primarily
responsible for the demise of the megafauna in a proposed "extinction
window" between 40,000 and 50,000 years ago, and points the finger
instead at climate change.
An international team led by the University of New South Wales, and including researchers at the University of Queensland, the University of New England, and the University of Washington, carried out the study. It is published in the Proceedings of the National Academy of Sciences.
"The interpretation that humans drove the extinction rests on assumptions that increasingly have been shown to be incorrect. Humans may have played some role in the loss of those species that were still surviving when people arrived about 45,000 to 50,000 years ago -- but this also needs to be demonstrated," said Associate Professor Stephen Wroe, from UNSW, the lead author of the study.
"There has never been any direct evidence of humans preying on extinct megafauna in Sahul, or even of a tool-kit that was appropriate for big-game hunting," he said.
About 90 giant animal species once inhabited the continent of Sahul, which included mainland Australia, New Guinea and Tasmania.
"These leviathans included the largest marsupial that ever lived -- the rhinoceros-sized Diprotodon - and short-faced kangaroos so big we can't even be sure they could hop. Preying on them were goannas the size of large saltwater crocodiles with toxic saliva and bizarre but deadly marsupial lions with flick-blades on their thumbs and bolt cutters for teeth," said Associate Professor Wroe.
The review concludes there is only firm evidence for about 8 to 14 megafauna species still existing when Aboriginal people arrived. About 50 species, for example, are absent from the fossil record of the past 130,000 years.
Recent studies of Antarctic ice cores, ancient lake levels in central Australia, and other environmental indicators also suggest Sahul -- which was at times characterised by a vast desert -- experienced an increasingly arid and erratic climate during the past 450,000 years.
Arguments that humans were to blame have also focused on the traditional Aboriginal practice of burning the landscape. But recent research suggests that the fire history of the continent was more closely linked to climate than human activity, and increases in burning occurred long before people arrived.
"It is now increasingly clear that the disappearance of the megafauna of Sahul took place over tens, if not hundreds, of millennia under the influence of inexorable, albeit erratic, climatic deterioration," said Associate Professor Wroe.
An international team led by the University of New South Wales, and including researchers at the University of Queensland, the University of New England, and the University of Washington, carried out the study. It is published in the Proceedings of the National Academy of Sciences.
"The interpretation that humans drove the extinction rests on assumptions that increasingly have been shown to be incorrect. Humans may have played some role in the loss of those species that were still surviving when people arrived about 45,000 to 50,000 years ago -- but this also needs to be demonstrated," said Associate Professor Stephen Wroe, from UNSW, the lead author of the study.
"There has never been any direct evidence of humans preying on extinct megafauna in Sahul, or even of a tool-kit that was appropriate for big-game hunting," he said.
About 90 giant animal species once inhabited the continent of Sahul, which included mainland Australia, New Guinea and Tasmania.
"These leviathans included the largest marsupial that ever lived -- the rhinoceros-sized Diprotodon - and short-faced kangaroos so big we can't even be sure they could hop. Preying on them were goannas the size of large saltwater crocodiles with toxic saliva and bizarre but deadly marsupial lions with flick-blades on their thumbs and bolt cutters for teeth," said Associate Professor Wroe.
The review concludes there is only firm evidence for about 8 to 14 megafauna species still existing when Aboriginal people arrived. About 50 species, for example, are absent from the fossil record of the past 130,000 years.
Recent studies of Antarctic ice cores, ancient lake levels in central Australia, and other environmental indicators also suggest Sahul -- which was at times characterised by a vast desert -- experienced an increasingly arid and erratic climate during the past 450,000 years.
Arguments that humans were to blame have also focused on the traditional Aboriginal practice of burning the landscape. But recent research suggests that the fire history of the continent was more closely linked to climate than human activity, and increases in burning occurred long before people arrived.
"It is now increasingly clear that the disappearance of the megafauna of Sahul took place over tens, if not hundreds, of millennia under the influence of inexorable, albeit erratic, climatic deterioration," said Associate Professor Wroe.
Story Source:
The above story is reprinted from materials provided by University of New South Wales.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- Stephen Wroe, Judith H. Field, Michael Archer, Donald K. Grayson, Gilbert J. Price, Julien Louys, J. Tyler Faith, Gregory E. Webb, Iain Davidson, and Scott D. Mooney. Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea). PNAS, 2013 DOI: 10.1073/pnas.1302698110
University of New South Wales (2013, May 6). Climate change, not human activity, led to megafauna extinction. ScienceDaily. Retrieved May 7, 2013, from http://www.sciencedaily.com /releases/2013/05/130506181711.htm
2 comments:
It is en vogue in our currently modern era to be biased towards blaming humanity for everything that happens that might conceivably be construed as negative. Not only is that as anthropocentric as the Medieval Catholic mindset of humanity being at the center of everything despite the fact it is coming from largely secular humanists but it inappropriately suggests extinction is a bad thing when ALL species ultimately go instinct and in the overall scheme of things humanity will have been responsible for a tiny fraction of a percent of all the species that ever existed on Earth.
Okies. First of all the Medieval Catholic Church did not set man as the center of everything. At the beginning of the Dark Ages, Augustine of Hippo created the "Great Chain of Being," wherein everything was listed in order of importance. It proceded as such:
God -> Angels -> Demons -> Man -> Woman -> Animals -> Plants -> Minerals. Man was never regarded as centric to the universe.
Second point, no one ever suggested that mass extinction was a bad thing, given that without the loss of the gigantisaurs, etc., the therapods would never have survived. And that's what ultimately led to us. However...
Third point. The problem is that today, there are species forever eradicated from the planet at the hands of humanity on a daily basis. Gone, thanks to eradication of habitats, hunting, pollution, and climate change caused by too many humans living mindlessly. And that's a crying shame.
I've helped to sue the US government in order to protect penguins. I have signed petitions and called lawmakers in order to protect wolves. And now I'm in a fight to save the wild cats of the world. The longer that greed prevails, the more animals will exist no longer. And that means that many more species will have gone the way of the dinosaur, but this time, at man's hands. We are stewards of the earth. We should act like it.
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