Understanding and Preventing Violence, Volume 2: Biobehavioral Influences (1994)
Chapter: INFRAHUMAN PRIMATE STUDIES
times the amount of circulating testosterone seen in their female counterparts. Intrauterine position in relation to male and female peers may, by changing early sex steroid exposure, consequently influence the potential for different types of behavior in adult mice (vom Saal, 1983). This has been confirmed in that 2M (developing between two males) female mice are aggressive toward and establish dominance over 0M (developing between two females) counterparts (vom Saal and Bronson, 1978). Further, after treatment in adulthood with testosterone, 2M female rats exhibited more mounting of receotive females than did 0M counterparts (Clemens et al., 1978).
It is well established (Brain et al., 1983) in rodents that the impact of castration on aggression becomes less evident in experienced fighters, which suggests that learning overrides hormonal influences. This having been said, there is also some evidence (in mice) that stimulation of gonadal function (e.g., by breeding activity), without the opportunity to fight, reduces the ease of demonstrating suppressed fighting postcastration. Perhaps some of the androgen-induced changes in aggressiveness are relatively persistent once generated?
There is also evidence that early exposure to stress (perhaps including the hormones of the pituitary-adrenocortical axis) modify the adult behavioral potentials (in terms of aggressive and emotional activities) of rats and mice (reviewed in Chevins, 1989).
INFRAHUMAN PRIMATE STUDIES
Goy (1968) studied the effects of early exposure of nonhuman primates to testosterone. Prenatal exposure to testosterone propionate masculinized the external genitalia of female rhesus monkeys and increased their rough-and-tumble and chasing play, features that are usually more typical of the male. Eaton et al. (1973) demonstrated that augmented aggression was still evident in ovariectomized and androgen-treated female adults who had been exposed neonatally to testosterone. Dixson (1980) reviewed the available data on such studies and concluded that "androgen administered prenatally has important consequences for behavior, including aggressive responses, in female rhesus monkeys." He suggested that testosterone (a major androgen in the circulation of fetal rhesus monkeys), which is present in much higher concentrations in males than females (Resko, 1974), influences brain development. Since progesterone is present in higher concentrations in female rhesus monkeys than in males (Resko, 1974), it
