Evolutionary anthropologists have long emphasized the puzzle of short inter-birth intervals, extended childhoods, and long post-reproductive lives of humans, in particular the problem it poses for raising children. While there is agreement that mothers receive assistance from kin to offset the high costs of raising children, opinion is equivocal as to which kin help and to what extent they help. Here the authors review 45 studies from historical and contemporary natural fertility populations to assess the effects of various types of kin on child survival rates.

This article explains the variation in inequality using a model in which a population's inequality depends on the extent to which its most important forms of wealth are transmitted within families across generations. Results suggest that economic systems differ substantially in the intergenerational transmission of wealth.