Hormones and Behavior
This chapter deals with hormonally influenced behaviors. The adult secretion of gonadal hormones plays a major and well-recognized role in the activation of copulation in all non-primate species. Under the influence of adenohypophysial hormones, the adult ovary secretes estrogen and progesterone, which act upon a neural substrate that has not been masculinized by perinatal androgens. The timing of nest building varies among species, but in all cases the placental, ovarian, and/or hypophysial hormones of pregnancy contribute to the behavior. The experience of previous maternal behavior can facilitate onset of the behavior and perhaps even decrease the requirement for gestational hormones. Sexually dimorphic behaviors are affected by the following three factors: organizational effects of gonadal hormones produced perinatally, activational effects of gonadal hormones produced during adulthood, and sexually dimorphic anatomy. Body size is sexually dimorphic in ways that probably contribute to aggression.