our models tell us ...

16 Aug 2015

At http://phys.org/print358679794.html ... we have one of those classic model studies that claim they have produced a 'cutting edge statistical analysis' which shows humans were responsible for the mass die-offs of animals over the last 70,000 years - which includes sabre toothed tigers as well as mammoths and woolly rhinoceros, giant sloths and giant armadilloes etc. Quite apart from having giant appetites, why would humans kill off all the prey species - out of devilment? One is also left stumped when their brilliance involves running thousands of pieces of data through their computers, locating when humans arrived (conjecture) and exactly when the die-offs occurred (relies on dating methodology which doesn't take much notice of C14 plateau events in the Late Pleistocene), and so on. They claim climate change only played a marginal role (does that rule out catastrophism)? The research, published in the journal Ecography, says the findings are 'beyond dispute' and 'man was the dominant force in wiping out megafauna' - which probably means they've got it all wrong.

Once again it is all down to what they put into the computer - as that will dictate what comes out of the analysis. No matter how many thousands of variations you input into your machine the answer will always be limited by what that input consists of (so the study is biased from the start). If you avoid catastrophism, and there were some very big events around 40 to 30,000 years ago, and around 18,000 and 13,000 years ago, and lesser events in between, you come up with a silly answer - which is what they retrieved from their machine. For an example of the silly answer, they say their findings debunk the idea of early humans living in harmony with nature, and the idea of killing the odd animal and making use of its skin, fur, bones, teeth, sinews etc after eating a fair proportion of the flesh. I wonder how many humans they factored into their computer analysis, or how big a population they thought existed in the Palaeolithic. It sounds a bit like that recent study where the researchers, noting humans made use of mammoth bones for shelter, assumed they had killed them off for that purpose rather than coming along, finding heaps of bones, and using them as a resource. Some people would think the obvious - other people will always take things literally, and extrapolate from the heap of bones. In reality, by avoiding catastrophism they are left with no other reason for a heap of mammoth bones other than human orientated. Why would you kill off a herd of mammoths in order to build a shelter, one that was not permanent?

After bragging about the statistical certainty the authors then reveal a touch of uncertainty. They say that mainland Asia remains a mystery as according to the fossil record that region suffered very low rates of extinction. Understanding why megafauna in mainland Asia is so resilient is the next big question. I was flummoxed by that as mainland Asia would presumably include Siberia where whole herds of horses were buried beneath sediments and bones of mammoth and other animals are so numerous on the Arctic coast they appear to form islands and have for centuries been exploited by the Chinese ivory trade. Perhaps the islands of bones is an exaggeration - is that what they are saying?

Mainland Asia, we may assume, is some other part of Asia - but it can't be China as fossil bones are very common. Was it the Middle East - the bones would have been ground down and used by humans long ago as it had a large population in relation to other regions - or are they referring to India (which may be underrepresented in the fossil collections). Either way their statistical methodology didn't come up with the right answers in mainland Asia - but they still went ahead with their claim. This more or less illustrates the open dispute between two camps as far as explaining mass die offs in the animal world in the Late Pleistocene - one side blames humans and the other side is inclined to blame climate change. The most obvious answer, catastrophism, is completely avoided. It's quite amusing to watch them lock horns - and become increasingly strident, stamping their feet on the ground and saying 'beyond dispute ...' and the like.