Some of the assumptions about how easy as HG life is may be incorrect. The 'average' life was easy. The book 'The Beak of the Finch' points out that the exceptional years are what cause all the stress. I considering what difficulties a HG faces, you need to look at the worst and best years. It does no good to live well for 10 years and then die in a drought year. Also you need to consider the really good years and their effect on population expansion pressures. R. Keene