ABSTRACT
The hypothesis that infanticide (i.e., the killing of conspecific young) is adaptive in some situations remains controversial. More generally accepted is the proposition that the killing of a member of one’s own species is maladaptive. Infanticide has therefore been regarded as a pathological behavior that only occurs in response to a breakdown in social structure (Calhoun, 1962; Curtin and Dolhinow, 1978). Although a breakdown in social behaviors and an increase in both infanticide and aggression between adults certainly occurs during times of social stress (Lloyd and Christian, 1969; Christian, 1971), this does not rule out the possibility that in other circumstances, infanticide may be adap tive. Hrdy (1979) has proposed four sets of circumstances under which infanticide would be adaptive. Her classification is based upon the nature of the benefit (mates, food resources, etc.) to the infanticidal animal (see Introduction, this volume). In this chapter, only one category of infanticide is discussed: that relating to sexual competition between males, which is referred to as “sexually selected’’ infanticide. Traits that enhance the ability of individuals to compete with members of the same sex for the chance to reproduce are thought to be subjected to sexual selection, which Darwin distinguished from natural selection (cf. Trivers, 1972).
