There’s no scientific evidence of that.
Here’s a previous thread:
http://boards.straightdope.com/sdmb/showthread.php?p=7893177&highlight=megafauna#post7893177
In N. America that’s some 35 genera claimed to be the victims of clovis man. We can tell this ONLY by the fossil record, thus in comparing extinctions, we need also to compare animals from recent periods that would also be clear from the fossil record. Rare or “unsuccessful” species don’t leave much of a fossil record. Nor do subspecies (it can be very hard to tell a species from just a few scattered fossil remains). Then again, what consitutes a subspecies is more open to change and interpretation- look at the Quagga for example, which was though originally to be a dsitinct species but DNA has shown it to be “merely” a subspecies (at best). We have very little DNA evidence to go on with the Pleitocene fauna, certainly not enough to assign subspecies with any amount of certitude.
So, when we are comparing extinctions, we have to compare like to like. We can’t compare apples to “all fruit”. In fact, I was being easy when I asked for “large successful mammal species”, as I should have asked for “large sucessful mammal genera”.
Even when we can point the finger at humans, hunting is not the only weapon in his arsenal. Martin used island extinctions are example, and uses New Zealand. No doubt, humans were a major force in the extinction of some 11 species of Moas:
http://www.unl.edu/rhames/courses/cu...m-overkill.pdf
“In no case is the precise cause or causes of these extinctions known. This is because in all known cases, human colonozation was associated with multiple possible impacts on the species that were lost. In New Zealand, for instance, people not only hunted moas, but they also set fires that quickly destroyed massive expanses of forest, and introduced competitors and predators in the form of rats and dogs. Some combination of hunting, introduced species (including pathogens) and anthropogenic vegetational changed caused the losses that are so well documented there. We cannot, however, say what that combination was. The same is true for all known prehistoric human-caused island extinctions. Becuase this is the case, none of these extinctions can be securely attributed to hunting alone, although this may have certainly occurred.” (italics mine)
If indeed, Human, or as Martin argues- Clovis man hunting, caused the megafaunal extinctions, you’d think there’d be more evidence. As of that article above (2002), there were exactly and only 14 (fourteen) sites that solidly show such evidence, and that evidence is confined to just two genera- mastadon, and mammoth. “… there are no demonstrable kill sites for camel or horse or for any of the remaining genera…”. In other words, looking purely at the record, Clovis man can be shown to have killed just a few mastodon and mammoth in North America. Oddly "After all, in other parts of the world- Late Pliestocene Europe, for example- are littered with sites that document human predation on large mammals. Martin claims that the killing in North America happened over such a short period of time that “we should not expect to find empirical evidence of that process”. “Martin argues quite differently for New Zealand, where he calls upon the abundance of archealogical sites containg moa remains to bolster his position that human hunting played a role in the extintion of these animals”. Seems sorta hypocritical to me.
In other words, for North America, where some 35+/- genera/species were wiped out, representing millions of very large animals, there are exactly 14 kill sites during the “blitzkrieg” and those show only two genera. Odd, it seems that Clovis man also had a team of thousands of CSI experts cleaning up after them, too!
Note also, that in order for Clovis man to be the killer of certain genera, that genus has to have been around when Clovis man arrived with his snazzy spears. “However, of 35 genera involved, only 15 can be shown to have lasted beyond 12,000 years ago. This leaves open the possibility that many of the remaining genera became extinct well before Clovis times.”
Finally “Martin has recently noted that archeaologists have always washed their hands of human complicty in large mammal extinction” in North America. He might also have noted that vertebrate paleontolgists who specialize in Late Pliestocene North America have also cleansed themselves of this notion. The reason is straightforward. There is no evidence for it, and much against it. While Martin claims that a lack of evidence provides strong support for his position, others have different expectations of the empirical record… Given that archeaologists and palaontologists have washed their hands of North American overkill, who accepts it and what explains it’s popularity? As we have mentioned, scientists that praise overkill are, by far and large, scientists who are not familiar with the details of the North American Late Pliestocene." “It is easy to show that overkill’s continued popularity is closely related to the political uses to which it can be put.”
If a Hypothesis had no valid data to back it up, it is “not valid”. I suppose “wrong” may be too strong a word, I concede. But it (the Overkill Hypothesis) has no valid data to verify it.
Sure, I have plenty of cites that show that the “Overkill Hypothesis” has no data. The “Overkill Hypothesis” does not state that human pressure was one of several factors- it states “that human hunters were responsible”. Period. And, that has been shown to be without any valid data, and several experiments/models have shown it is very likely wrong- that climatological changes were also very important.
I stated very clearly “Three things led to the megafauna extinction: Climate change (the same climate change that allowed humans to spread), new species (of which humans were one, sure, but many other species came along- including our friend the rat), and new diseases spread by those new species…”, thus I agreed that humans were a definate factor. Just not THE only factor.
And, it’s not “scientists”- it’s one dude. Martin. He wrote a very exciting argument, one that many laymen found convincing. Unfortunately, real scientists need data, not just arguments. I find Martins hypothesis no better than the “Aquatic Ape” Hypothesis. Both sound good, neither have any real data to back them up. (I enjoyed the AA hypothesis myself, it’s just that it’s without any data. )
No doubt that hunting played a part. That human changes to the evironment played a part. But also that climatological changes played a part too. AND, there may have been other significant factors that we don’t know about- disease, maybe.
Here’s more:http://www.pnas.org/cgi/content/abstract/99/23/14624
"Understanding of the Pleistocene megafaunal extinctions has been advanced recently by the application of simulation models and new developments in geochronological dating. Together these have been used to posit a rapid demise of megafauna due to over-hunting by invading humans. However, we demonstrate that the results of these extinction models are highly sensitive to implicit assumptions concerning the degree of prey naivety to human hunters. In addition, we show that in Greater Australia, where the extinctions occurred well before the end of the last Ice Age (unlike the North American situation), estimates of the duration of coexistence between humans and megafauna remain imprecise. Contrary to recent claims, the existing data do not prove the “blitzkrieg” model of overkill. "
In other words, actual scientific results show that the “overkill hypothesis” is wrong.
http://www.sciencemag.org/cgi/conten...ct/306/5693/70
One of the great debates about extinction is whether humans or climatic change caused the demise of the Pleistocene megafauna. Evidence from paleontology, climatology, archaeology, and ecology now supports the idea that humans contributed to extinction on some continents, but human hunting was not solely responsible for the pattern of extinction everywhere. Instead, evidence suggests that the intersection of human impacts with pronounced climatic change drove the precise timing and geography of extinction in the Northern Hemisphere. The story from the Southern Hemisphere is still unfolding. New evidence from Australia supports the view that humans helped cause extinctions there, but the correlation with climate is weak or contested. Firmer chronologies, more realistic ecological models, and regional paleoecological insights still are needed to understand details of the worldwide extinction pattern and the population dynamics of the species involved.
This article puts the nail in the myth of the “Overkill position”
http://www.unl.edu/rhames/courses/cu...m-overkill.pdf
“The arguements that human hunters were responsible for the extintion of a wide variety of large Pleistocene mammals emerged in Western Europe during the 1860’s… Today the overkill position is rejected for wetsern Europe but lives on in Austrailia and North America. The survival of this hypothesis is due almost entirely to Paul Martin… In North America, archaeologists and paleotologist whose work focuses on the late Pleistocene routinely reject Martin’s postiion for two prime reasons: there is virtually no evidence that supports it, and there is a remarkably broad set of evidence that strongly suggests that it is wrong. In response, Martin asserts that the overkil model predicts a lack of supporting evidence, thus turning the absences of empirical support into support for his beliefs. We suggest that this feature of the overkill position removes the hypothesis from the realm of science and places it squarely in the realm of faith. One may or may not believe in the overkill position, but one should not confuse it with a scientific hypothesis about the nature of the North American past.”
