 The basic idea is that psychological altruistic dispositions can evolve as proximate mechanisms or “modules” for promoting the biological advantages relevant to the forms of selection listed above. In some cases, these adaptive psychological mechanisms will involve specifically targeted or conditional altruistic motivations, involving capacities for discrimination to focus benefits on kin or on reciprocators. In other cases, the selection pressures will give rise to less discriminating altruistic sentiments and tendencies as the simplest and most cost-effective mechanisms for promoting adaptive cooperative behaviors in a given environment. If our hominin ancestors tended to live in circumstances where the opportunities for ‘wasting’ altruism in non-fitness-enhancing ways (e.g., on ‘outsiders’) were sufficiently few and far between, then a simple, undiscriminating (though limited) sense of concern and altruism may have promoted fitness at far less cost than more discriminating forms, evolving more readily. One advantage of this hypothesis is that it might help explain some sorts of concern and altruism that are otherwise hard to make sense of in evolutionary terms.