Evolutionary biologists normally have to stress to us the mind-boggling time spans required to cause significant changes in human beings, but recent research has revealed a crucial genetic mutation only a few thousand years ago in the European population which could have given them a crucial head-start in the development of civilisation.
In the Japanese company I work for we pool together to buy milk for our teas and coffees, but none of the Japanese are part of this pool. This is because they, along with virtually all East Asians, are lactose intolerant. This means that after early childhood they lose the ability to digest milk. The same goes for the indigenous populations of Africa, Australia and the Americas. DNA testing of Neolithic European skeletons from around 5000BC shows that these people also did not possess the lactase gene necessary for lifelong digestion of milk.
Early Europeans already had some advantages over the populations of other continents. Luck had provided them with the most suitable crops and the most domesticable animals, and a geography which enable their populations to spread easily and grow their food and farm their animals wherever they went (I recommend Jared Diamond's book Guns, Germs and Steel for more detail on why native Europeans were able to gain advantages over other civilisations and ultimately colonise other continents rather than the other way round).
This new study shows that when Europeans started to farm cows they were still lactose intolerant, so they domesticated them purely for meat and as beasts of burden. At some point after 5000BC it seems that a genetic mutation in one individual led to such a significant genetic advantage that the gene spread rapidly to virtually the entire European population. This ability to drink milk provided early Europeans with a year-round supply of nutrients, protecting them to some extent from failing crops. This additional source of nutrition provided another step forward in the move away from subsistence farming and towards sedentary populations, and from there to organised societies and advanced civilisation.
posted by Kevin @ 1:57 AM
2 Comments:
But milk is the main item of diet of the Hereros of Namibia.
Thanks for your comment Steve. You are right to question my broad generalisations. A bit more research on my part has led me to discover that the patterns of lactose intolerance seem to indicate two or three evolutionary start points of lactose tolerance.
As well as the European development I mentioned, it seems likely that there was an independent evolution of lactase capability in the nomadic populations around the Sahara. The Bedouin and Tuareg populations show much higher lactose tolerance than the settled population of the region.
Another start-point is proposed among the pastoral Tutsi population of the Rwanda-Uganda area, although there is some doubt as to whether this is an independent development.
What interests me is that this capability spread in Europe so quickly, but in spite of exposure from colonisation and globalisation does not seem to have spread so rapidly to other populations. However, this may have to do with the usefulness of this ability. Among populations with dairy animals it would give a much clearer advantage than to those without. Do the Hereros herd cattle. If they did this at the time of introduction of the lactase gene from an outside source, I guess this could spread pretty quickly by dint of the significant advantage it would give (as it did in Europe). Just my theory which is probably a product of a little knowledge being a dangerous thing, but I thought I'd share it anyway.
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