In The Bridge to Humanity: How Affect Hunger Trumps the Selfish Gene, renowned scholar Walter Goldschmidt demonstrates that culture operates by means of biological mechanisms that came into being by an evolutionary process. Central to the book's main focus is the recognition of the separate evolutionary origin of what we call love: sexual and nurturant. These ancient heritages demand very different forms of behavior; one essentially competitive and the other concerned with mutuality. Underlying nurturance is the phenomenon of "affect hunger," an urge to seek the affection that is needed for the proper development of the neurological system in humans and other social mammals. Goldschmidt analyzes how affect hunger not only provides a reward system for learning language and other cultural information, but also remains a motive for social behavior throughout life.