I propose a multidisciplinary project on the evolution of moral behavior, connecting the evolutionary theory of altruism and cooperation to several behavioral sciences. The research subject is approached by focusing on the evolution of an agent with the psychological profile of a contractarian moral agent – in the Kantian rather than Hobbesian tradition –, which implies that fairness and a respect for persons as equals are intrinsically valued, without denying that humans also exhibit a natural tendency to betray these values. The evolutionary explanation faces two challenges, both addressed by the project: the paradox of biological altruism, i.e., the fact that altruistic traits seemingly contradict the theory of natural selection, as first noted by Darwin (1871); and the need to theorize over a plausible phylogenetic origin of moral agents. Building upon recent proposals that link human cooperation to motivations to comply with norms of fairness and to punish norm-violations, the project proceeds along the following hypotheses: 1. In the evolution of morality, individual and group selection are not opposed, but synergistic forces. The psychology of normendorsement is designed to support social practices and institutions that suppress the advantages of selfish, freeloader behavior. Under these conditions, moral behavior benefits both the individual and the group. 2. All human cooperative strategies, strong reciprocity, indirect reciprocity, and reciprocal altruism are norm-guided, and guided in fact by the same general norm of conditional or reciprocal cooperation. 3. Concerning the phylogenesis of moral agents, the selection pressures responsible for the evolution of the appropriate moral psychological architecture began only to operate after humans had developed the ability to perceive the opportunities for cooperation with delayed reciprocity in interactions with a prisoner’s dilemma structure. 4. The suitable interaction type for promoting the evolution of fairness norms was not contest for dominance between males, but interaction between males and females for the rearing of offspring. This interaction has the structure of a prisoner’s dilemma. It requires the fulfillment of expectations for mutual constraints on behavior and favors the evolution of fairness. Once the psychological profile for human long-term mating strategies evolved, involving male parental investment and trust between sexual partners, the profile influenced other social interactions.