The so-called “selfish gene” theory, technically known as gene selection, is an elaboration of work done by W.D. Hamilton and G.C. Williams on a phenomenon known as “kin selection.” Kin selection is predicated on the idea that the impulse I feel to care for my nephew is stronger than the impulse I feel to care for (say) my neighbor’s nephew. I know that my nephew is my sister’s son, and that my sister and I were born of the same parents; I therefore know that he carries 50% of my sister’s genetic alleles, and that there’s a 50% chance that any one of my sister’s alleles is one that I also carry. For any one of my nephew’s alleles, then, there’s a 25% chance that I also carry that allele. If I care for my nephew, then my genes have a one in four chance of helping themselves; if I care for my neighbor’s nephew, the odds are much, much lower. Gene selectionists therefore argue that genes are the individuals who benefit in the process of natural selection. Hence Dawkins’ famous claim that organisms are “gigantic lumbering robots” for carrying genes around: I have an impulse to care for my nephew because it helps (some of) my genes, even though it hurts me as a whole.
In 2010, E.O. Wilson and two collaborators wrote an article in Nature attacking the viability of kin selection. We won’t get into the details of their mathematical argument; the bottom line is that things rarely work out so neatly as “my nephew has half of my sister’s genetic alleles and she has half of mine,” and the complexities ultimately call into question the idea that gene selection can explain altruistic behavior. In his newest book and a recent New York Times “Stone” column (interestingly, a philosophy blog!), Wilson proposes an alternative that he calls “multi-level selection.” His account is so called because Wilson believes that nature sometimes selects genes, sometimes selects organisms, and sometimes selects groups—and that the latter option is the one that explains altruism. It was this claim that prompted Dawkins’ scathing review of Wilson’s book, linked in the first paragraph. Undermining the very foundation of Dawkins’ account of selection probably had something to do with it, too.