parental investment theory

n. Parental investment theory is an important middle-level theory in evolutionary psychology that makes predictions of sex-differentiated behavior. The basis for this theory is that it is common in nature for males and females to have asymmetrical patterns of parental investment. Among the mammals, the obligatory costs of reproduction are relatively high for females because reproduction requires a period of gestation and lactation, whereas the obligatory costs of reproduction for males are relatively minor. As a result, the higher-investing sex (females) becomes the limiting resource in mating. The prediction is that females will be discriminating maters, seeking investment and other resources such as emotional commitment and good genes from males. Mating is expected to be problematic for the low-investment sex, with the result that males must often compete with other males for access to females. Successful males have often been able to mate polygynously and to have access to younger, more desirable mates. This theory makes a number of predictions. Males and females are expected to have different patterns of sexual jealousy: Male sexual jealousy is predicted to be based on concern with paternity certainty because their partner's infidelity could lead them to invest in another man's children. On the other hand, female sexual jealousy is expected to center around concerns that her partner may develop an emotional relationship with another female and not continue to invest in their relationship. Males are also predicted to be more aggressive and more prone to risk taking because these behaviors have a greater potential payoff in terms of reproductive success. However, because females are the high-investment sex, mating for females is much less problematic, with the result that females are expected to pursue less risky behavior, to show a greater tendency toward fear, and to exhibit less aggression. Evolutionary psychologists have amassed considerable support for these 
hypotheses. – KM