Contrary to what some scientists have asserted previously (see here and here), there’s no good evidence that humans were responsible for the extinctions of around 90 giant animal species that once roamed Australia – including the Diprotodon pictured above, a hippopotamus-sized giant wombat that roamed Australia until 46,000 years ago. In fact, most of these species had already disappeared by the time people arrived. That’s the conclusion reached by an international team of scientists in a major review of the available evidence, and published recently in the Proceedings of the National Academy of Sciences (abstract here). The study concludes that climate change, rather than overhunting by the first human beings to settle in Australia, was what brought about the demise of these species.
The study, which is titled, Climate change frames debate over the extinction of megafauna in Sahul (Pleistocene Australia-New Guinea), was led by the University of New South Wales, and which included researchers at the University of Queensland, the University of New England, and the University of Washington. The study’s title refers to the continent of Sahul, which comprised mainland Australia, New Guinea and Tasmania, during the Pleistocene epoch (popularly known as the “Ice Age”), when the sea level was as much as 150 meters lower than it is today.
“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 the University of New South Wales, 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.
The term “megafauna” refers to giant animals weighing more than 100 kilograms, or 220 pounds.
Of the 90 or so megafauna (“giant animal”) species that became extinct, about 50 are completely absent from the fossil record of the past 130,000 years, which is about 80,000 years before the first human beings are believed to have arrived in Australia and New Guinea. There is only firm evidence for 8 to 14 megafauna species still existing when Aboriginal people arrived in Australia, and there is no evidence to suggest the Aborigines were responsible for their dying out.
Summing up the conclusion reached the study, lead author Stephen Wroe stated: “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.”
The study’s conclusion adds to a growing mass of evidence suggesting that human beings are not the ecological “baddies” that they are often made out to be. The extinction of the North American megafauna some 13,000 years ago has been blamed on overhunting by the first human settlers – but now this theory looks increasingly unlikely (see here).
How animal extinctions are being used as anti-human science propaganda: the myth of the “Sixth Wave”, and the man who exposed it
In more recent times, the threat of large-scale species extinction, caused by the destruction of animals’ habitats, is often put forward as an argument for human population control. It is said that we are now in the middle of a great wave of species extinctions, unparalleled since the extinction of the dinosaurs. These claims have been thoroughly debunked by amateur scientist Willis Eschenbach, over at Watts Up With That?, the world’s most viewed site on global warming and climate change. In a January 2013 post titled, Always Trust Your Gut Extinct, Eschenbach writes:
…[T]this is the first scientific question I seriously researched. It is also the reason I don’t trust the “experts” or the “consensus”. In 1988, E. O. Wilson, an ant expert with little knowledge of extinction, made a startling claim that extinction rates were through the roof. He claimed there was a “Sixth Wave” of extinctions going on, and that we were losing a huge amount, 2.7% of all the species per year. This claim quickly went viral and soon was believed by everyone. So back in 2003, a decade ago now, I researched the question, found that Wilson was wrong by orders of magnitude, wrote it up, sent it around to the journals to see if they would publish it, and … well, let me just say that I was not received kindly. I was a voice crying in the wilderness. They didn’t give me a look-in, I was challenging the consensus. As far as I know, I was the only one saying that Emperor Wilson had no clothes … and as a result, I was not encouraged to continue publicizing my views.
But the world goes on, and three years ago I simplified and streamlined my work and published it as a post on WUWT entitled ““Where Are The Corpses“. In it, I argued that there was no “Sixth Wave” of extinctions, that Wilson’s numbers were wildly exaggerated, and that current extinction rates (except in isolated islands and Australia) are not unusual in any way. Dr. Craig Loehle rewrote and developed the ideas, and he got it peer-reviewed and published in Diversity and Distributions, available here. Craig wrote about it in a post entitled “New paper from Loehle & Eschenbach shows extinction data has been wrongly blamed on climate change due to island species sensitivity“. Title says it all …
Instead of 33 mammals and 80 birds going extinct on the continents per decade, in the last 500 years on the great continental landmasses of the world, we’ve only seen three mammals and six birds go extinct. Only nine continental mammal and bird species are known to have gone extinct in 500 years. Three mammals and six birds in 500 years, that’s less than one continental mammal extinction per century, and these highly scientific folks are claiming that 30 mammals and 80 birds are going extinct per decade? … once again I’m forced to ask, where are the corpses?
… Because the reality is that despite humans cutting down the forests of the world at a rate of knots for hundreds and hundreds of years, despite clearcutting for lumber, despite slash-and-burn, despite conversions to cropland, despite building hundreds of thousands of miles of roads and fences, despite everything … only nine continental mammal and bird species have gone extinct.
Eschenbach is greatly concerned that his findings will be misused to justify deforestation, and in his article, ““Where Are The Corpses“, he emphatically declared that he intends no such thing:
None of this implies that habitat destruction, forest fragmentation, or loss of species diversity are incidental or unimportant issues…
None of this implies that extinctions will either rise or fall in the future…
And finally, none of this implies that habitat destruction has no effect on the risk of extinction.
Nevertheless, he felt compelled to state:
Extinction records do show that on all the continents of the world, there are no recorded cases of a forest bird or mammal that has gone extinct from any cause. This is despite the fact that humans have been reducing and fragmenting all natural habitats, including first the continental temperate forests and lately the continental tropical forests, for the 500 years covered by our extinction record.
More alarmism in the name of “science”: “Has the Earth’s sixth mass extinction already arrived?”
Back in 1988, evolutionary biologist E. O. Wilson’s claim that a “Sixth Wave” of extinctions was already well underway. Claims like Wilson’s have continued down to the present day. Two years ago, a team of scientists led by Anthony D. Barnosky warned that another mass extinction was imminent, in an article published in the journal Nature (Volume 471, pp. 51–57, 3 March 2011, DOI:
doi:10.1038/nature09678, published online 02 March 2011), entitled, Has the Earth’s sixth mass extinction already arrived?. The authors concluded that most of the world’s creatures are in danger of becoming extinct. Here is an excerpt from the abstract of their paper:
Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.
Other scientists weren’t impressed by the alarmists’ arguments. Barnosky’s paper received damning reviews from other researchers, and even from some ecologists. Greenpeace co-founder and ecologist Dr. Patrick Moore sharply criticized the new study for claiming that an irreversible mass extinction of species was already underway. “This [journal Nature] article should never have made it through the peer-review process,” Moore told Climate Depot in an interview. “The fact that the study did make it through peer-review indicates that the peer review process has become corrupted,” he said.
Dr. Moore has also criticized biologist E. O. Wilson for claiming that a sixth extinction event has already begun. Back in 2000, when Wilson estimated that up to 50,000 species go extinct every year based on computer models of the number of potential but as yet undiscovered species in the world, Moore commented: “There’s no scientific basis for saying that 50,000 species are going extinct. The only place you can find them is in Edward O. Wilson’s computer at Harvard University. They’re actually electrons on a hard drive. I want a list of Latin names of actual species.”
A recent study in Science magazine, titled, Can We Name Earth’s Species Before They Go Extinct? (M. J. Costello et al., Science 25 January 2013: Vol. 339 no. 6118 pp. 413-416), acknowledges that alarmist claims of a sixth wave of extinctions are overblown:
Some people despair that most species will go extinct before they are discovered. However, such worries result from overestimates of how many species may exist, beliefs that the expertise to describe species is decreasing, and alarmist estimates of extinction rates.
Even this study, though, suggests a figure of “500 to 50,000 extinctions per decade if there are 5 million species on Earth.” Eschenbach takes the study’s authors to task for their methodological bias:
Like many modern scientists, rather than trying to find the most probable, they simply assume the worst. So they give their calculations assuming a 1% decadal extinction rate. Here’s the problem. That’s no more believable than Wilson’s 2.7% per decade rate. There are about 3,300 mammal species living on the continents (excluding Australia). If we assume that one percent of them go extinct per decade, that would mean that we should be seeing about 33 continental mammal extinctions per decade. It’s worse for birds, a 1% extinction rate for birds would be about 80 continental birds per decade. We have seen absolutely nothing even vaguely resembling that. That’s only slightly below Wilson’s estimate of a 2.7% extinction rate, and is still ridiculously high…
This kind of world-blindness astounds me. I’ve heard of living in an ivory tower, but if you were making the claim that it’s raining, wouldn’t you at least look out the ivory windows to see if water were actually falling from the sky? How can you seriously claim that we’re losing dozens and dozens of species per year when there is absolutely no sign of that in the records?
The power of one – and why you should trust your gut instincts
At the end of his post, Eschenbach talks about his one-man fight against the scientific establishment:
People are always giving me grief about how I’m not getting with the picture, I’m not following the herd, I’m not kowtowing to the consensus. I have no problem doing that, particularly given my experience regarding extinctions. For years I was the only person I knew of who was making the claim that E. O. Wilson should have stuck to his ants and left extinctions alone. Wherever I looked scientists disagreed with my findings. I didn’t have one person I knew, or one person I read, who thought I was right. Heck, even now, a decade later, the nettle still hasn’t been grasped, people are just beginning to realize that they were fools to blindly believe Wilson, and to try to manage a graceful climb down from the positions they took.
What I learned in that episode was that my bad number detector works quite well, that I should stick to my guns if I think I’m right, and that I should never, ever, ever place any faith in the opinions of the experts. They were all wrong, every single last swingin’ Richard of them, and I was right. Doesn’t mean I’ll be right next time, I’ve been wrong plenty both before and since … but it has given me the courage to hold on to some extremely minority positions.
It is my strong belief that I will also be vindicated in my claim that the earth’s temperature is regulated, not by CO2, but by a host of interlocking and mutually supportive homeostatic mechanisms that maintain the temperature within a fairly narrow range … time will tell. In my opinion, the experts in the climate field have shown that they don’t know a whole lot more about the real underpinnings of the climate than E. O. Wilson knew about extinctions … but that’s just me, and YMMV.
Maybe there is a message here for us in the Intelligent Design movement. What do readers think?