In applying the economic perspective to behavior over the life cycle, it is usually appropriate to adopt a universalist view of humanity–a view that emphasizes the similarity of human experience across eras, continents, and individuals. Birth and death, the beginning and the end of each human life, are the same regardless of how varied are the years in between. From biology and psychology come many insights about developmental processes that are experienced by all or nearly all individuals, Moreover, every society needs a system for the mating of adults of childbearing age, a system for caring for helpless infants, a system for educating and socializing the young, and a system for producing and distributing goods and services.