Parental Investment Theory
Gregory D. Webster
Parental Investment Theory is a biological theory that attempts to explain the dynamic, give-and-take relationships among parents, their offspring, and limited resources. In many species, parents are forced to make a difficult choice between investing in themselves (e.g., survival, mating) and investing in their offspring (e.g., feeding, protection). Although both parents typically have a shared interest in the survival of their offspring, males in most species invest substantially less in their offspring than females, due in part to the fact that females must carry their offspring to term and often provide food, breast milk, and protection. This biologically based sex difference in parental investment has several implications for sexual and familial human relationships. This entry describes the theoretical background of parental investment, summarizes related biological theories such as Inclusive Fitness Theory, and discusses Parental Investment Theory's implications for attachment patterns, human development, and sexual and familial relationships in humans. In ...