Now to the next book "The Causes of Progress". I seem to have found some thing for my old age. Some hints, empirical stuff, lot of speculation and hand waving, some things that can be tested but always other causes and alibis for exceptions. These are books from eighties, seem to be ignored in the Anglo-Saxon world and so probably not much research to check them against ( I found one. Testing Todd: Global Data on Family Characteristics). But engaging and stimulating.