[Voluntary, controlled limited reproduction in humans--a conflict to modern evolutionary biology?]

In western industrialized countries it is widespread to limit individual reproduction voluntarily and deliberately. This phenomenon of minimizing reproduction conflicts with the maximization of biological fitness, expected on the basis of sociobiology. Some positions and attitudes of demography and sociobiology that appear to be contradictive are critically discussed, and with several examples it is expounded that we are dealing with misunderstanding rather than inconsistencies in many cases. The majority of misunderstandings can be put down to an inadequate differentiation between proximate and ultimate levels of causation. However, proximate interpretations of the problem of minimizing reproduction from a sociobiological perspective are frequently unsatisfactory. Therefore, the demographic model of "competing pleasures of life" (Konkurrenz der Genüsse) was connected with evolutionary biology. Combining demographic and biological aspects reveals that human striving for material and non-material values (pleasures of life), originally was highly adaptive and fitness-enhancing as behaviors to acquire resources and secure social status. Not until a society offered a variety of behavioral and consumer alternatives and simultaneously sophisticated methods of contraception these behavioral patterns dissociated from their function of survival and became independent.