Thursday, September 26, 2013

Paleolithic Population Expansion Claim Does Not Add up.

It has long been believed that the rise of agriculture and animal husbandry helped produce an explosion in the human population in the Neolithic Period (about 10,000 years ago).   Now a new study that has taken a detailed look at the genes of 66 human ethnicities claims that the expansion actually took place much earlier, in the Paleolithic, as long as 80,000 years ago.  The summary of the research can be found here.

I would like more details about how their figures for the age at which the population expansions were calculated.  They report " the authors also demonstrate that the populations who adopted a sedentary farming lifestyle during the Neolithic had previously experienced the strongest Paleolithic expansions."

They speculate that these societies benefitted from some technological advantage which allowed for their populations to greatly expand, while other populations which stayed hunter-gatherers did not see much change.  That really does not make any sense to me.   The populations which became farmers later somehow were the ones that expanded, even before they changed to farmers and herders?   

Maybe most folks new how to farm already, but there was no need for it until population density reached a point where you really had to work at it to be a hunter-gatherer?   Or maybe, and this is one of those things that post-modern science is not allowed to speculate on, there method of calculating dates based on a reading of genetic changes is seriously off.   That is, the expansion really did occur around 10,000 years ago, but the mutation rate they used to calculate it is in error, giving dates of 60,000 years or even more.

It makes more sense for the rise in population to coincide with the rise of agriculture, and it makes little sense that the ones who later adopted agriculture were the only ones to show a dramatic population boom 50,000 to 60,000 years before they developed the means to feed such an increased population.   It makes more sense for the boom to be very closely associated with the technology which can sustain it- farming and herding.  But this would mean their methodology about determining dates by measuring changes in genes over time was deeply flawed, a prospect that not many in the field are willing to take a hard look at these days.


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