•Differences exist between men and women in size of certain brain areas.
Effects of Sex Hormones on Nonsexual Characteristics •Women tend to be better than men at recognizing facial expressions of emotion.•In one study, women’s task was to examine photos of faces and try to identify the expressed emotions among six choices: anger, disgust, fear, happiness, sadness, and surprise. •After women received testosterone, most became less accurate at recognizing facial expressions of anger.
Parental Behavior – Hormonal Changes •Hormonal changes prepare a female mammal to provide milk.•And to prepare her to care for young.•After a mother rat delivers her babies, she increases her secretion of estradiol and prolactin, while decreasing production of progesterone.•Necessary for milk production.•Enables mother to eat more than usual.•Responsible for some maternal behavior.•Inhibits sensitivity to leptin, enabling the mother to eat far more than usual.
Parental Behavior – Hormonal Changes •Late in pregnancy, female brains increase sensitivity to estradiol in the areas responsible for maternal behavior and attention to the young.•Medial preoptic area and anterior hypothalamus. •We discussed the POA/AH because of its importance for temperature regulation, thirst, and sexual behavior.
Parental Behavior – Hormonal Changes •Vasopressin:•Hormone synthesized by the hypothalamus.•Secreted by the posterior pituitary gland.•Associated with social behavior in many species.•Facilitates olfactory recognition.
Parental Behavior•If a female that has never been pregnant is left with some baby rats, she ignores them at first but gradually becomes more attentive. •After about 6 days, the adoptive mother builds a nest, assembles the babies in the nest, licks them, and does everything else that normal mothers do, except nurse them. •This experience-dependent behavior does not require hormonal changes and occurs even in rats that had their ovaries removed.
Parental Behavior•Mothers with a deficiency of the alpha type of estradiol receptor provide only poor maternal care—for example, not licking and grooming their offspring enough to provide normal stimulation. •Humans show genetic variation in their alpha estrogen receptors, and one study found that women with one of the genetic variants were more likely than average to treat their young children harshly, both physically and verbally.
Parental Behavior•On average, a man’s testosterone level decreases and his prolactin level increases after a baby is born, especially if the man spends hours a day interacting with the child. •Men with the lowest testosterone levels and highest prolactin levels spend the most time playing with and caring for their children.
10.2 Variations in Sexual Behavior•People vary in frequency of sexual behavior, preferred types of sexual activity, and sexual orientation.