Inclusive Fitness and the Sociobiology of the Genome

Hamilton’s Rule provides conditions for the evolutionary success of a gene. These conditions ensure that the gene is selfish in the sense described by Richard Dawkins (1976). By this very fact, inclusive fitness does not explain why the genome of a successful species consists of genes that predominantly cooperate in promoting the fitness of their carriers. Hamilton’s rule shows that prosocial altruistic genes, antisocial predatory genes, and antisocial spiteful genes can all enjoy evolutionary success, and gives no reason why or how the prosocial altruistic genes come to predominate in successful organisms. The genome evolves when it suppresses alleles that detract from, and promotes alleles that enhance, the fitness of the reproductive population. This implies first that genes do not maximize inclusive fitness but rather interact strategically in complex ways involving collaboration, promotion, and suppression across loci and across individual carriers. It also implies that for any species there is a core genome that specifies the common phenotypic characteristics of the species, including biochemical interactions among loci and social interactions among individuals. The core genome, not the gene, is the central replicator in species evolution. Hamilton’s Rule provides conditions for the evolutionary success of a gene. These conditions ensure that the gene is selfish in the sense described by Richard Dawkins (1976). In particular, as Hamilton’s rule makes clear, the conditions for the evolutionary success of a gene are distinct from the conditions under which the gene enhances the fitness of its carrier. However, it is equally true that the evolutionary success of a gene does not ensure that it enhances the mean fitness of members of the reproductive population. Therefore inclusive fitness does not explain why the genome of a successful species consists of genes that predominantly I would like to thank Samuel Bowles, David Haig, Steven Frank, Peter Godfrey-Smith, David Queller, Laurent Lehmann, Samir Okasha, Peter Richerson,Joan Roughgarden, Elliot Sober, and Mattijs van Veelen for advice in preparing this paper.