Strategies of adaptation: interpopulation selection differentials.

Spatial and temporal variation of selection intensities has been analyzed using published data on Crow's indices in 278 human populations, representing various anthropological types, religions, cultures and a wide spectrum of environmental conditions. Statistical analysis has shown that populations with different types of economy have different adaptive strategies. In tribal populations both components of selection-differential fertility and differential mortality-have equal contributions, vary according to ecological factors and show no decline with time.