Galor and Moav argue that evolution would respond by building stronger bodies in high-disease environments, and the result would be longer lifespans once those dangers of disease recede in the modern world.

This seems unsupported - I thought the "antagonistic pleiotropy" theory was that things that help you when you're young will hurt you when you're old (e.g. tesosterone makes you stronger in youth, gives you prostate cancer when old, etc). So a high-disease environment could _lower_ lifespan limits by favoring genes that help you survive long enough to reproduce, but then kill you once you've shot your fitness wad (so to speak).

tc, that is my first thought too. i'm going to dig deeper into the paper and come back with a comment. if anyone needs an example of what tc is talking about, think sickle cell anemia or cystic fibrosis. there is some benefit in the het. state that increased the frequency of the derived alleles (in sickle cell it is malaria, which became endemic after agriculture).

tc,

Indeed--Galor and Moav push hard for somatic investment--a win-win story--over a more brutal (and more economic-sounding) trade-off story.

But where there are puzzling facts to be explained--like big differences in average life expectancy across countries and "continental groups" that persist even after controlling for the usual suspects, it's time to try some theorizing.....So I welcome their efforts.

It's more likely an increasing degree of adaptation to a high-carbohydrate diet. There are other factors worth considering: wimp neurological adaptations that decrease interpersonal violence,
maybe differential resistance to undiscovered or poorly understood pathogens involved in chronic diseases. Selection for increased IQ could also increase lifespan summat.

I haven't really read this properly, but I note that the main determinant of life expectancy (at birth) in pre-industrial societies is the level of infant mortality. Typically, about 1 in 3 babies die in the first year, and cumulatively about 1 in 2 by the age of 15. Those who get over the perils of childhood have a reasonable expectation of getting to age 60 or more.

David, if you take people who were very recently hunter gatherers and put them into a modern society, then infant mortality drops to about the same level as the surrounding society due to modern health care, but as adults they suffer higher rates of chronic diseases like Type 2 diabetes and such. There are other factors which help to explain shorter life expectancy, like poorer standards of health care later in life, poorer living standards generally, drinking problems and such, but it seems very evident that a high carb high glycemic index diet affects them particularly badly.

Such a group are already descended from those survivors who had natural immunity to the diseases that killed off all of their contemporaries when they first came into contact with Europeans, so I suspect Greg Cochran is right about progressive adaptation to a high carb diet.