Is Kin Selection Wrong?

In a stunning example of the inevitable marching forward of science, prominent ecologist E.O. Wilson, famed for helping lay the groundwork for modern theories which explain the genesis of social evolution, is now rejecting his own work. Originally, the favored explanation for altruistic behavior - one of the foundations of sociality - was kin selection. Kin selection is an evolutionary theory which asserts organisms can increase their fitness through actions which harm them individually. As long as their actions benefit other organisms which share, or are likely to share their genes, the altruist increases its inclusive fitness.

This was widely supported in the ecological community, because many of its predictions were born out. Organisms which resided in community nests developed sociality faster than organisms which lacked them. Organisms with strong family-rearing instincts formed into colonies of social organisms more frequently than lone wolf species.

However, according to Wilson, all that is circumstantial. In his new paper, Wilson cites group selection as the driving force behind altruism and, by extension, sociality. Group selection differs from kin selection mostly in the level of selection. Kin selection takes place at the genetic level, because inclusive fitness can increase and decrease regardless of which individual organism carries the genes. Even if an allele codes for a suicidally altruistic behavior, if that behavior causes enough relatives to survive and thereby increase the frequency of the gene in the next generation, it is still a beneficial trait. In contrast, group selection takes place at the level of organism group. Competition between groups of organisms puts a separate set of selective pressures on the individuals in the groups, promoting behaviors like selflessness and altruism, because groups made of those types of individuals out-compete groups of selfish jerks. Wilson asserts that in this scenario, high relatedness within groups is a symptom of close proximity for some time, no a cause of group formation in the first place.

Wilson’s new theories are extremely controversial within the scientific community - many ecologists consider him to have lost credibility for suggesting that kin selection is false. As for myself, I don’t think that Dr. Wilson should lose credibility, but I am not sure if I believe his assertions. His theory of group selection does not adequately explain why groups of cooperating organisms formed in the first place. Furthermore, kin selection makes several predictions which group selection does not, which nature has proven to be true. For example, kin selection implies that organisms with higher relatedness should be more social. Lo and behold, order hymenoptera, a haplodiploid gender determinant group, has a higher proportion of eusocial organisms than any other order. Given that one quirk of haplodiploid sex determination is a higher relatedness to one’s siblings than to one’s own children, it is easy to see how this supports kin selection.

You can read E.O. Wilson’s entire paper at http://www.biology.ed.ac.uk/archive/conferences/evolbiol2006/papers/Wilson.pdf and come to your own conclusion about this large debate.

-Adam Geiger