The Critique of Biochemical Group Selection

Biological group selection is based on unstated assumptions about the relationship between genetic variation and phenotypic variation. The first models of altruism made a simplifying assumption that behavior was caused by a single allele, let's say selfishness. And so if you imagine you have a multi-group population and each group is colonized by a certain number of individuals, then the amount of genetic variation among groups will depend on the number of individuals that colonize each group. Group selection can't really be a very strong force under that scenario.