Wednesday, 16 November 2011

Martin is blaming the humans...

So as I promised in my last blog, I am going to give an overview of Martin’s general theory, specifically focusing on Australia. 

The first point Martin makes in this article is that the global extinctions at the end of the Pleistocene follow the pattern of the first Homo Sapiens, but ‘the extinction pattern does not obviously track changes in climate throughout the Pleistocene’ (1984). Pointing out that the spread of the first humans was confined to the very end of the Pleistocene when the extinctions occurred, whereas changes in the climate have been continually changing but no extinctions of the amplitude have ever been seen. So basically, the extinctions were following man’s footsteps; hence they are the consequence of man’s actions.

Martin also hypothesises that the first humans would have found the large mammals easy to hunt because the mammals wouldn’t have developed or evolved defensive mechanisms against human predation. For example the lumbering diprotodontids with their small platigrade feet who would not have been able to run fast enough, or the giant kangaroos who were much less gracile than their relatives living today (1984).

But the problem that even Martin himself points out is that there is much uncertainty over the dating of macrofossils of various extinct megafauna. North America has rather rigorous comparable techniques with sloth dung or bone amino acids residues, but no such comparable organic carbon source is available in Australia (1984). Even the famous Lancefield site relies on only 2 charcoal dates that mark the macrofossils as 26,000 years old. There have been other rather more postulating estimates of dating at other sites that are still disputed. Such as a dozen bone points from Devil’s lair in western Australia estimated at 29,500 years old and even an articulated human skeleton at Lake Mungo dating 28,000 years, Jones (1980) even goes as far to say that there are 29 sites with human remains predating 15,000 years (Dortch 1979; Bowler and Thorne 1976). So surely this all points to humans occupying Australia much earlier than the late Pleistocene extinction, an argument truly challenging the ‘overkill hypothesis’ pointed out by Martin.

Another thing that Martin covers is the fact that there are very few sites that contain both extinct macrofossils and human remains. In fact the only evidence found to date of both remains together are of 3 Sthenurus tooth fragments at Seton’s Cave, all of the other sites of human remains are only with existing faunal today (1984). Which again I see as strong evidence that humans didn’t have a large impact on the extinction of the megafauna; surely there would be more evidence of such a huge impact no? Martin puts this down to what he calls ‘Blitzkrieg’ (look to the glossary for meaning), so basically faunal overkill that maximises speed intensity of human impact and minimises time of overlap between the first human invader and disappearance of native fauna (Mosimann and Martin 1975). Something I just can’t agree with, just because something happened quickly doesn’t mean it doesn’t leave any evidence as if it had never happened, if something happened there is always evidence whether it was quick or not. He points to the fact that the North America extinction was much later hence why there is more evidence there are human megafauna interaction, that is a lose hypothesis, but a more solid one would be to blame the climate.

So all in all, I think Martin’s theory doesn’t fit Australia, he seems desperate to fit his hypotheses to the evidence and that shows in the weak connections he makes. He finishes with the need for judicious radiocarbon is imperative, which I definitely agree with, no theory can be rejected until a solid dating foundation is given. But if some of the dating estimations already given are true, then humans were around for a very long time before the extinctions and hence the ‘overkill hypothesis’ is not valid. Even Martin himself admits, ‘Australia may offer the best opportunity for refutation of prehistoric blitzkrieg’ (1984).

Because these references are not available on the internet:

Bowler, J.M and A. G. Thorne (1976) ‘Human remains from Lake Mungo: discovery and excavation of Lake Mungo III’, in Kirk, D. L and A. G. Thorne (eds) The origin of Australians, Canberra, Australian Institute of Aboriginal Studies.

Dortch, C. E. (1979) ‘Devil’s Lair, an example of prolonged cave use in southwestern Australia’, World Archaeology, 10, 258-281.

Jones, R. (1980) ‘Geographical background to the arrival of man in Australia’, Archaeological Physics, Anthropology, 3, 186-215.

Martin, P. S. (1984)  'Prehistoric Overkill: the global model', in Martin, P. S. and R. S. Klein (eds) Quaternary Extinctions: a Prehistoric Revolution, Arizona, University of Arizona Press, 354-604.

Mosimann, J. E. and P. S. Martin (1975) ‘Simulating overkill by Paleoindians’, American Scientist, 63, 304-313.

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