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Humans show a great deal of variability in their reproductive behavior, including types of sexual activity, types of ties between males and females, and ways of arranging for the rearing of offspring. We will consider three principal topics: (1) Father absence versus father presence, contrasting children who are reared in a family system in which there is a closely involved and economically contributing father in contrast to a family system in which women rear their children in cooperation with other women (usually kin) and without consistent help from a man who is father to children. (2) Peer rearing versus parent rearing, concerning who does the primary work of rearing children—whether biological parents themselves and in a proximate sense provide for the care of their own children or whether parental surrogates do the major child tending work under some form of distal parental supervision. (3) Pair-bonding between parents versus individual strategies that do not include reciprocation with a mate, with a view toward understanding several psychiatric “disorders” as manifestations of more general evolved propensities against cooperation.
In the first two cases we discuss the consequences which being reared under one or the other of these conditions can have for the individual’s reproductive strategy. For simplicity we portray the conditions as dichotomous alternatives but we recognize that in actual life individual experience can vary along a continuum from one to the other. There are data on these topics, and evolutionary theory can help us understand these patterns in a way that takes account both of environmental differences among groups and the evolved characteristics of our species.
The evidence about why some adults seem to prefer to bond with one individual of the opposite sex while others mate in quite different contexts is quite sketchy. We will discuss characteristics of sociopaths and hysterics, individuals with clusters of traits identified by psychiatrists and usually interpreted as victims of mental illnesses. We will point out that these trait clusters seem to make good sense when considered in the light of the evolutionary theory of reproductive strategies, even though there is no good evidence of learning or of effects of rearing environment on their development.
Our view of learning is that humans have been selected to be differentially sensitive to certain cues in their immediate early childhood environment (Bowlby 1969, 1973; Lumsden & Wilson, 1981; MacDonald, 1984). It is as if human young acquire early socialization with their antennae tuned to detect certain attributes in their environment, especially the role played by mother’s mate and the mother’s attitude to her mate(s), and the role of parents as opposed to nonparental surrogates in providing proximate care in early childhood. These are examples of contextual variables which influence learning tracks in early childhood and which can be understood in the context of our evolutionary past.