Comments by "Iain Mc" (@iainmc9859) on "Your DNA and the Digestion of Milk…" video.

  1. Tolerance levels increase with greater exposure, even within the lifetime of an individual. Not just to foodstuffs but also to allergies, bacteria or viruses. So there can't be any surprise that those people that live in an environment well suited to the production of certain foodstuffs become tolerant of it, even at a genetic level, over a few generations. Evolution isn't a steady progression, its episodic, with sudden rushes and lulls. For example, Japanese people were genetically very unsuited to the high levels of salt in processed food that came with American 'culture' after WWll. This created quite a lot of severe ill health, soring levels of high blood pressure. Within two generations this has almost levelled out on a par with western tolerance levels. Another Japanese example, there are some women in Japan, generally older ladies, that catch (by hand) water snakes; a bite from which would kill a westerner within hours, not so these old ladies. You put a young Japanese woman from a city in the same work environment I suspect they'd be in intensive care within the week. Environmental tolerance adaption is a powerful human tool, genetics take a while to catch up. The short version of the above is - survival is probably based on you adapting to the biome you live in, rather than your genetic make up. This, over time, is written into the genetics and probably not the other way round.
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