Adaptation and natural selection: A new look at some old ideas

The debate between individual-and group-selection perspectives centers on the probability that group selection played a major role in evolution, which may depend on the species being studied. To explore the viability of group selection for altruism, I present fitness indexes for altruists, nonaltruists, and groups when the parameters of costs, benefits, and proportion of altruists in a group are varied. © 1994, Cambridge University Press. All rights reserved.