But as Sober and Wilson (1998) have argued with great clarity, there is no simple connection between evolutionary theory and the philosophical debate between egoism and altruism. This is because the concept of altruism that is important in evolutionary theory is quite different from the standard concept of altruism invoked in the philosophical debate. For biologists, an organism behaves altruistically if and only if the behavior in question reduces its own fitness while increasing the fitness of