Evolutionists from Darwin to the present have discussed the problem of the units of selection. Darwin understood the issue as follows: Do traits evolve because they benefit individual organisms or because they are good for the group in which they occur? More recently, a third alternative has been proposed--that it isn't the organism or the group that is the unit of selection; rather, traits evolve because they benefit the genes that code for them. This issue becomes important because of the issue of evolutionary altruism. An altruistic trait is none that reduces the fitness of organisms that possess it while benefitting the group in which it occurs. Altruistic traits are bad for the individual but good for the group. In the past ten years, there has been a considerable amount of interest among both philosophers and biologists in the unit of selection problem. Some of their work has been in reaction to the ideas presented by the two investigators in this project, specifically, Professor Wilson's study of 1980 and Professor Sober's work of 1984. Under this grant, Professors Sober and Wilson are collaborating to evaluate the work over the past decade and produce a synthetic treatment of where the conceptual issues now stand. They are also investigating possible connections between the issue of evolutionary altruism and selfishness and the psychological issues and altruism and egoism. Although the evolutionary and psychological concepts are logically independent of each other, the question remains of how one might argue for or against theses concerning their empirical connection.
