Behaving like the other sex has been observed in a number of species of mammals, although such behaviour is generally more common in the female than the male. This study discusses why such capacity is so common in sexually differentiated animals.

1 Are behaviours specific to animals of particular sex?.- 2 Sex typicality and sex conformity.- 3 Prenatal gonadal influences on mouse sociosexual behaviours.- 4 Heterotypical sexual behaviour in female mammals.- 5 Heterotypical sexual behaviour in male mammals: the rat as an experimental model.- 6 The development of sexuality and eroticism in human kind.- 7 Neuroendocrine differentiation of sex-specific gonadotropin secretion, sexual orientation and gender role behaviour.- 8 Biological and psychological factors in human aggression.- 9 Heterotypical behaviour in man and animals: concepts and strategies.