Altruism and fairness: Unnatural selection?

Darwin admitted that the evolution of moral phenomena such as altruism and fairness, which are usually in opposition to the maximization of individual reproductive success, was not easily accounted for by natural selection. Later, authors have proposed additional mechanisms, including kin selection, inclusive fitness, and reciprocal altruism. In the present work, we explore the extent to which sexual selection has played a role in the appearance of human moral traits. It has been suggested that because certain moral virtues, including altruism and kindness, are sexually attractive, their evolution could have been shaped by the process of sexual selection. Our review suggests that although it is possible that sexual selection played such a role, it is difficult to determine the extent of its relevance, the specific form of this influence, and its interplay with other evolutionary mechanisms.