SG: Most hunter gatherers were lucky to live to the age of 35. Their skeletons show evidence of all kinds of illness, disease and poor nutrition.

The "lucky to live to the age of 35", if true, is likely a result of animals or injury. Lacking a critical mass of a reservoir for the microbes, diseases were rare, no? These came with settled groups and their garbage, plus the larger populations, and the domestication of animals. (They did pick up such ailments as botulism, gangerine, rabies, or typhus.)

Refer to such books as The Greatest Benefit to Mankind by Roy Porter for evidence. http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dst...

If your evidence is mostly from crop makers, it doesn't apply here. I lack your experience, but I read a lot.

Wild-assed supposition: We are genetically disposed to live about 70 years. This gets us well past child bearing years, so why do we live so long? My conjecture is that the old people took care of and educated the children while the more able-bodied adults foraged or hunted, thus there was an environmental pressure to live longer than child-bearing.

Count Uptoten