Genetic similarity theory: a reply to Mealey and new evidence.

Abstract

Mealey's criticisms of genetic similarity theory (GST) (Rushton,et al., 1984) are rebutted as either based on a misreading of its claims or a failure to grasp the nature of such theorizing. We argue that, if a gene can ensure its own survival by acting so as to bring about the reproduction of any organism in which copies of itself are to be found, then GST is a worthwhile alternative to kin selection theory. The most effective way for this to be accomplished is for organisms to be able to detect copies of its genes in others, and proffer preferential treatment to those most similar. We report novel data congruent with this hypothesis: (a) spouses assort more on the basis of the more genetically influenced of a set of homogeneous traits (i.e., there is a positive correlation between assortative mating coefficients and heritability estimates), and (b) following the death of a child, parental grief intensity is correlated with the child's similarity to the parent.