Even if infant mortality is discarded, average life expectancy is a poor estimator of typical expectations of life. Considering the case of pre-industrial socie

Even if infant mortality is discarded, average life expectancy is a poor estimator of typical expectations of life. Considering the case of pre-industrial societies, there was a second big wave of mortality during what we now call adolescence. In women it was driven by child bearing, while in men by either accidents or armed conflict with other groups of men. If half of the guys that make it to their 13th birthday will get themselves killed before their 21st, an average of 40 y.o. gives a very misleading idea of what "old folks" look like.