Industrialised food systems generate foods and drinks in the shops, and therefore diets, that are pathogenic. I don't think Jeff Leach meant to suggest that I have any other view!
He mentions the OkinawansReference Willcox, Willcox, Todoriki, Curb and Suzuki1 and HunzakutsReference McCarrison2 as examples of peoples whose traditional food systems have enabled healthy and long lives, and proposes that these are examples of different types of optimal diets revealing the human potential life span. I agree that this potentially is an important argument. The gerontologist Roy Walford has also claimed, from work on experimental animals, that the maximum human life span is around 120Reference Walford3. The convergent evidence here seems to be on the general benefits of energy restriction to levels well below what is generally now considered ‘normal’, together with simple and very nutrient-dense diets. Perhaps this is a way to ‘cheat nature’.
The theory that humans are evolved and adapted to live until their children are adults, and then – with some exceptions – to die, is I still think the most reasonable working hypothesis, simply because – as I mentioned – there is no evident selective advantage in living longer.
