Oh the IRONY: White supremacist's home defaced after revelations about his ‘African’ DNA

[bhikkhu]

14. It is a tricky subject, and easy to overstate the point in either direction

but there have been studies based on burials and historic records which include only those who reached adulthood, to arrive at an estimate of life expectancy for those who survived the infant mortality problems of the past. Mid forties is a good estimate.

http://www.sarahwoodbury.com/life-expectancy-in-the-middle-ages/

I've read several like this from similar studies, even one from Pre-spanish Mexico, which surveyed burial sites and, not accounting for children, found that adult remains averaged around 40 years old.

The availability of food has been one big change, as technology has steadily increased the reliability and abundance of the food supply. Even in the 1700's, I've read that in most areas of the world famine was, on average, a once every 15 years occurence. The difficulty of transport made things worse, as a crop failure in on region couldn't be practically mitigated by an abundance in another region. Famine led directly to disease (more often than starvation), especially prior to medical advances.

Digging a bit more - here's a good write-up on that: http://johnhawks.net/weblog/reviews/life_history/age-specific-mortality-lifespan-bad-science-2009.html