  To some extent, the idea that kin-directed altruism is not ‘real’ altruism has been fostered by the use of the ‘selfish gene’ terminology of Dawkins (1976). As we have seen, the gene's-eye perspective is heuristically useful for understanding the evolution of altruistic behaviours, especially those that evolve by kin selection. But talking about ‘selfish’ genes trying to increase their representation in the gene-pool is of course just a metaphor (as Dawkins fully admits); there is no literal sense in which genes ‘try’ to do anything. Any evolutionary explanation of how a phenotypic trait evolves must ultimately show that the trait leads to an increase in frequency of the genes that code for it (presuming the trait is transmitted genetically.) Therefore, a ‘selfish gene’ story can by definition be told about any trait, including a behavioural trait, that evolves by Darwinian natural selection. To say that kin selection interprets altruistic behaviour as a strategy designed by ‘selfish’ genes to aid their propagation is not wrong; but it is just another way of saying that a Darwinian explanation for the evolution of altruism has been found. As Sober and Wilson (1998) note, if one insists on saying that behaviours which evolve by kin selection / donor-recipient correlation are ‘really selfish’, one ends up reserving the word ‘altruistic’ for behaviours which cannot evolve by natural selection at all.