[QUOTE=John Mace]
With all due respect, all but one of your cites are abstracts, and I don’t know how one goes about refuting an abstract. And I think you’re overstating the case when you insist on labeling the overkill hypothesis as stating that extinctions were caused solely by humans
Now, your finale cite is indeed a paper that claims that climate was the major cause, and the writers seem to have an almost personal animosity towards Martin. Whether or not that paper has become the new consensus, I would look to someone like **Colibri **to answer that question. This was, is and always will be a debate among scientists and scientists in certain fields are not always going to agree with scientists in other fields.
At any rate, you are now saying that you agree largely with what was said in the origional GD thread, so maybe I just misread your first few posts, but you sure seemed to saying that climate change is viewed as the major cause when you posted these:
[/QUOTE]
Here’s a line from that last cite: “More than 40 years ago, Paul S Martin began to develop what has become the most visible explanation for these losses: the extinctions, he argues, were due entirely to the impacts of human hunting.” (cited and footnoted) To make things straight- the “Overkill” (aka
the “Blitzkrieg”) hypothesis does exactly claim that- the extinctions were due entirely to the impacts of human hunting. Note that **Colibri ** agrees that this is bunk "One scenario, however, that has not been confirmed is Paul Martin’s extreme “blitzkrieg” hypothesis for the extinction event in the Americas due to the rapid expansion of Clovis hunters. It’s now pretty well established that the human presence in the Americas predates Clovis, and that humans co-existed with the megafauna for longer than had initially been supposed. The process may have been “sitzkrieg” (attrition) rather than blitzkrieg."
Just in case you think my last cite was improperly citing Martin, here is another:
http://www.amnh.org/science/biodiversity/extinction/Day1/overkill/Bit1.html
And another:
"*Evolutionary biologist Jared Diamond embraced it in his popular books, 1992’s The Third Chimpanzee and again in Guns, Germs, and Steel: The Fates of Human Societies, which won the Pulitzer Prize in 1998. In a 2005 book, Twilight of the Mammoths: Ice Age Extinctions and the Rewilding of America, Martin extends his argument that “virtually all extinctions of wild animals in the past 50,000 years are anthropogenic.”
But not everyone is convinced.
Russ Graham, director of Penn State’s College of Earth and Mineral Sciences, cites a dearth of actual kill sites and other exceptions to the overkill chronology. “We’ve come a long way in the last 30 years as we’ve developed new techniques,” he says, referring to isotopic analysis of fossils, computer models and new archeological discoveries. “All they have is timing,” he says of overkill theorists.
Anthropologist Donald Grayson shares Graham’s suspicion that unwarranted enthusiasm for anthropogenesis is “playing a major role” in diverting attention from alternative explanations. In a chapter of a forthcoming book on the arrival of the first North Americans, Grayson attributes the bias to a political agenda: “One may applaud the intent, but it is hard to avoid the fact that overkill’s continued popularity in this context appears more closely related to the environmental movement than to any supporting evidence.”
In a recent paper in the Journal of Archaeological Science titled “A requiem for North American overkill,” Grayson and fellow archeologist David Meltzer point out that Martin’s theory was published five years after the appearance of Rachel Carson’s exposé of the dangers of chemical pollution, Silent Spring, and the same year as the founding of the Environmental Defense Fund.
“We suggest that the overkill argument captured the popular imagination during a time of intense concern over our species’ destructive behavior toward life on Earth. It retains that grasp today,” they wrote. “It is easy to show that overkill’s continued popularity is closely related to the political uses to which it can be put.”*
John, you’re a great guy, and I am not going to class myself with Colibri, but you don’t seem to grasp this basic issue- the Overkill/Blitzkreig hypothesis is on a line with the Aquatic Ape hypothesis- it’s an extremist idea with few expert backers and less facts. It’s really not too unfair to compare it to the IPU, Martins idea is that far off. *Martin * is not saying “Humans are the major cause” (something which I can buy) he is saying “human hunting is the sole and only cause”- and over a very very short period. Bunk.
Now, it seems obvious that most of the real experts in this field now accept there are several factors- human intervention and climate change being the major causes. I agree. **Colibri ** seems to weigh in that Human intervention being more important that climate, but depending on the local and period, if I read him correctly. This is fine by me, but I take a more “we aren’t sure” position, that’s all.
Rattus sp has caused more actual extinctions that us humans with puny spears clutched in our opposable thumbed hands. Of course, when H.Sapiens introduces Rattus, the forthcoming extinctions can be laid at our feet. My only “excuse” is the rather feeble “um, err, Rattus has been known to travel on it’s own, and err, umm, we didn’t mean to”. In fact, I personaly doubt if human *hunting * was a major cause (and that’s just an opinion, not back by much at all). But I have no doubt that humans certainly were.
). It wasn’t “successful” (at that point in time anyway) and likely Steller just hastened the extinction by a few decades. Sad story though.
don’t drink too much! 