The Evolutionary Psychology FAQ

Edward H. Hagen, Institute for Theoretical Biology, Berlin

Why are adaptations not for the good of the species?

Adaptations evolve through the differential reproduction of alternative alleles within a population or species. Thus, organisms acquire properties which allow them to out-reproduce members of their own species, not members of other species. It is theoretically possible for the differential survival of gene pools (species) to result in the evolution of organism features which would promote species survival at a personal reproductive cost to individual members of the species; it is extremely unlikely, however, that this process is responsible for the incredible array of complex functionality evinced by sexually reproducing, diploid species (Williams 1966). The length of time between speciation or extinction events is vastly longer than the length of time between generations. Consequently, differential reproduction of alleles within species can produce complex functionality much faster than can differential reproduction between species. An allele that provided a benefit to the species at an expense to the individual would be driven to extinction long before it could have a measurably positive impact on the survival of the species. (There are other forms of group selection, however, that are worth considering; see, e.g., Sober and Wilson Unto Others).

Copyright 1999-2002 Edward H. Hagen