In most cultures, extramarital sex is highly restricted for women. In most of those cultures, men transfer wealth to their own sons. In some cultures extramarital sex is not highly restricted for women, and in most of those cultures, men transfer wealth to their sisters' sons. Inheritance to sisters' sons ensures a man's biological relatedness to his heirs, and matrilineal inheritance has been posited as a male accommodation to cuckoldry—a paternity strategy—at least since the 15th century. However, longitudinal analysis of (...) the cumulative effect of female extramarital sex indicates that matrilineal inheritance is most advantageous for women and would be more accurately considered a grandmaternity strategy. That is, if the probability that men's putative children are their biological children is less than 1, the probabilistic degree of relatedness between a female and her matrilineal heirs is higher than her corresponding relatedness to her patrilineal heirs. The same holds true for men only if ρ is very low. The upshot is that for moderate levels of female extramarital sex, matrilineal inheritance, relative to patrilineal inheritance, is highly advantageous for women and disadvantageous for men. Consideration of female variance in reproductive success beyond the first generation, and of a man's network of obligation to the inclusive fitness of his relatives, suggests that although the establishment of matrilineal inheritance may require extremely high levels of female extramarital sex, once established, it is likely to be maintained at levels of ρ that reasonably characterize many societies in the ethnographic record. New analysis of previously published data shows a strong association between matrilineal inheritance and moderate to low probability of paternity, and an even stronger relationship between patrilineal inheritance and high probability of paternity. (shrink)

Several attempts have recently been made to explain moral systems and moral sentiments in light of evolutionary biological theory. It may be helpful to modify and extend this project with the help of a theory of communication developed by ethologists. The core of this approach is the idea that signals are best seen as attempts to manipulate others rather than as attempts to inform them. This addition helps to clarify some problematic areas in the evolutionary study of morals, and it (...) generates new, testable predictions about moral statements. (shrink)

Despite wide acceptance that the attributes of living creatures have appeared through a cumulative evolutionary process guided chiefly by natural selection, many human activities have seemed analytically inaccessible through such an approach. Prominent evolutionary biologists, for example, have described morality as contrary to the direction of biological evolution, and moral philosophers rarely regard evolution as relevant to their discussions. -/- The Biology of Moral Systems adopts the position that moral questions arise out of conflicts of interest, and that moral systems (...) are ways of using confluences of interest at lower levels of social organiation to deal with conflicts of interest at higher levels. Moral systems are described as systems of indirect reciprocity: humans gain and lose socially and reproductively not only by direct transactions, but also by the reputations they gain from the everyday flow of social interactions. -/- The author develops a general theory of human interests, using senescence and effort theory from biology, to help analye the patterning of human lifetimes. He argues that the ultimate interests of humans are reproductive, and that the concept of morality has arisen within groups because of its contribution to unity in the context, ultimately, of success in intergroup competition. He contends that morality is not easily relatable to universals, and he carries this argument into a discussion of what he calls the greatest of all moral problems, the nuclear arms race. (shrink)