It wasn’t climate change, asteroid impact, or habitat change. Human hunting was maybe a factor-
Why did the giant bison, mammoth, mastadon, giant ground sloth, etc. disappear so quickly? There are a number of hypotheses. This article describes some progress.
Dung Fungus Provides New Evidence in Mammoth Extinction. By Betsy Mason. Wired Magazine
If it was human induced, the evidence says it must have people before the relatively sophisticated Clovis culture.
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Just because you can’t “rule out” a human cause for the mass extinction of megafauna species, does not necessarilymean we should point our fingers in that direction either. There is a paper by Shapiro et al. 2004 (The rise and fall of the Beringian Steppe bison) that used ancient DNA evidence collected from bison remains excavated in Beringia. Their analyses indicate that a population bottleneck occurred much further back in time before humans could have had any influence on their decline. We shouldn’t jump the gun here and start pointing our fingers at the paleoindians or their predecessors. Think about it…How large would the human population have to be and what kind of technology would they have used to cause such a sudden mass extinction of over 34 species?! I’m thinking they should be looking for evidence of some kind of infectious disease. Maybe some kind of extremely virulent virus?
Here is a recently published paper that suggests an indirect human cause…the introduction of diseases through human migration, Anthrax in this case. Article link below:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2653229/pdf/pone.0004813.pdf
There was a population of Mammoths that survived in the Arctic on Wrangel Island north and west of the Bering Straits. Those mammoths lived till 1800 B.C.(!) , only four thousand years ago and many thousands of years longer than our Columbian mammoths and other megafauna. They had downsized into what we would call dwarf mammoths, probably adapting to available forage, like the miniature African elephants that were once found on Malta and hunted away. Wrangel Island is well offshore from Siberia and would have been more isolated from humans. There is some scant archaeology that indicates the Wrangel mammoths did in fact disappear at the same time as the first stone tools and other human habitation evidence is found . Ivory tools were carbon dated. Today it is home to polar bears and wolves and the. The place has a storied myth and history . Even though Wrangel is north of Siberia, it was claimed by a US Naval Captain and named “New Columbia”. It was first described by none other than John Muir , and Jules Verne set a tale there. The Soviet Union had a prison camp there…probably the most wretched venue on the planet for such things , for both prisoners and guards.
It would be interesting to know if recovered mammoth DNA from Wrangel Island would be more viable for purposes of cloning since it is so much younger.
Here’s another possible explanation for the mass extinction of megafauna…Climate change. See the link below:
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8362000/8362203.stm
The question as to whether humans were responsible for the megafauana die-off at the end of the Pleistocene seems driven, in the absence of adequate evidence and more importantly, inadequate experimental design and statistically rigorous on the ground sampling for testing the hypothesis, by ideology.
Many on the left (e.g., conservation biologists) wish to use paleo-humans, including Paleo-Indians in North America, as a kind of shorthand for the undeniable damage humans have done to land, water, and wildlife since the rise of agriculture post-Pleistocene and argue for the restriction of human economic activity and expansion of conservation reserves. Humans are bad.
Many on the right wish to use anthropogenic megafauna extinction to demonstrate that native peoples weren’t the original conservationists and that human activity on the land, at any degree, is as natural now as it was 10,000 years ago, as is extinction, so it is absurd to restrict human economic activity now (e.g., Charles Kay). Humans are good.
Interestingly, both left and right tend to blame Paleo-Indians for the megafauna extinctions in North America. A sure indicator that ideology is more involved than science.
It strikes me that both positions are nonsense. Humans are both bad and good–who can deny that? Read the Greeks and Shakespeare for examples.
The problem is that we simply don’t have adequate evidence and thus understanding of the role of paleo-humans in their environment. With some exceptions, mostly from DNA evidence pointing to a genetic bottlenecks 120,000-90,000 years ago and following human migrations out of Africa, we have no clue as to human population numbers throughout the Pleistocene and still have inadequate evidence, archaeological or otherwise, as to the ecological impacts of their extraordinary technological development and accomplishments (e.g., Clovis) throughout the Pleistocene.
There is no smoking gun to suggest a human cause, to put it bluntly. We can’t even find the gun or assume one was involved.
In short, we just don’t know what the role of humans was in the megafauna extinctions. Consequently, it’s safer, as Petticoat Rebellion suggests, to look elsewhere. The science of genetics, as in her example of Berengian bison, may be our best source of information about what happened to the megafauna.
My own view is that until the development and rise of agriculture, a process that has allowed humans a certain degree of independence from ecological limits, we should view the relationship between humans and animals, especially the megafauna, in terms of predator-prey dynamics. Just as most of us understand that predators–e.g. wolves–don’t drive their prey to extinction, so should we consider it highly unlikely that paleo-humans drove their prey to extinction.
RH