Comment by dpq

I can't quickly find the paper but I recall having read something along the following lines: there were several areas in Greece where people consumed meat and cheese heavily but the life expectancy was decent. A subsequent investigation showed that the villagers had a very common SNP (mutation) which reduced the efficiency of LDLR (essentially making their bodies ingest less of the "bad" cholesterol into the bloodstream). And the theory went that since these populations had the same diet for centuries, everybody who was not very adapted to it sort of died out / was outcompeted in a Darwinian way by folks who had this genetic adaptation. So yes, a Sardinian villager may live to 102 eating solely mutton; it doesn't mean that the outcome would be as good if you took a random sample of Californians (for instance) and had them use the same diet.