must all be taken into account Human Sexuality The scientific study of sexuality is multidimensional—biological, psychological, social, and cultural factors must all be taken into account

Human Sexual Response First mapped by sex research pioneers William Masters and Virginia Johnson during the 1950s and 1960s Human sexual response can be described as a cycle with four stages: Stage 1: Excitement—beginning of sexual arousal Stage 2: Plateau—increased physical arousal Stage 3: Orgasm—male ejaculates, female vaginal contractions Stage 4: Resolution—arousal subsides

What Motivates Sexual Behavior Necessary for the survival of the species but not of the individual Lower animals motivated by hormonal changes in the female (estrus) Higher species less influenced by hormones and more by learning and environmental influences

Hormones & Sexual Response Women A woman’s fertility is regulated by monthly hormonal cycles but these hormonal changes seem to have little or no effect on a female’s sexual motivation. Even when a woman’s ovaries, which produce the female sex hormone estrogen, are surgically removed or stop functioning during menopause, there is little or no drop in sexual interest.

Hormones & Sexual Response Men When human males experience lowered levels of testosterone because of illness or castration (removal of the testes), a drop in sexual interest tends to occur, although the effects vary among individuals In both men and women, sexual motivation is biologically influenced by levels of testosterone in the body

Evolution and Mate Preferences David Buss coordinated a large-scale survey of more than 10,000 people in 37 different cultures Men and women across all 37 cultures generally agreed that they wanted a mate who was kind and understanding, intelligent, emotionally stable, and healthy, and who had a pleasing personality Men were more likely to value youth and physical attractiveness; women valued financial security, access to material resources, high status and education, and good financial prospects Evolutionary psychology’s explanation for these gender differences is that mating behavior is adaptive to the degree that it furthers the reproductive success of transmitting one’s genes to the next generation and beyond

Sexual Behavior over the Lifespan

Sexuality During Infancy & Childhood The capacity of the human body to show reflexive sexual responses is present at birth. Infants as young as three or four months of age will smile or coo as they engage in genital play. Signs of sexual activation or genital play should not cause alarm in parents, because such behaviors reflect completely normal developmental patterns. Young children become keenly attuned to parental attitudes, especially negative attitudes, concerning nudity, genital touching, and genital exploration. Awareness of sexual matters expands during middle and late childhood. By about age eight, most children are aware that certain behaviors produce erotic feelings.

Sexuality During Adolescence Puberty—stage where an individual reaches sexual maturity and is physically capable of sexual reproduction Primary sex characteristics—sex organs directly involved in reproduction Secondary sex characteristics—develop during puberty, not directly involved in reproduction, but distinguish male from female Adolescent growth spurt—period of accelerated growth during puberty Menarche—female’s first menstrual period Romantic and sexual relationships become increasingly important in adolescence

Timing of Puberty Both genetics and environmental factors play a role in the timing of puberty Girls often experience menarche at about the same age as their mothers did. Generally, well-nourished and healthy children begin puberty earlier than do children who have experienced serious health problems or inadequate nutrition. In general, heavy children begin puberty earlier than do lean children, and girls involved in physically demanding athletic activity can experience delays in menarche

Romantic Love and the Brain Research results suggest that love activates brain areas that are involved in other positive emotions, such as happiness, but in a way that represents a unique pattern. Looking at a photo of one’s romantic partner produced heightened activity in four brain areas associated with emotion: the anterior cingulate cortex, caudate nucleus, putamen, and insula. These are the same brain areas that are activated by euphoria-producing drugs, such as opiates and cocaine.

Sexuality in Adulthood Majority of adults (80%) report having none or one sexual partner in the past year (marriage factor) Majority of men ages 18-59 have sex about seven times per month Majority of women ages 18-59 have sex about six times per month Vaginal intercourse is nearly universal as the most widely practiced sexual activity among heterosexual couples 50 percent of older Americans reported sexual activity at least once per month.

How Often Do You Think About Sex ? The percentages shown here were derived from a national survey based on a random sample of American adults between the ages of 18 and 59. As you can see, although most men seem to think about sex more often than most women do, there is overlap between the sexes in this respect.

Sexuality in Late Adulthood According to one survey, among older Americans nearly half reported engaging in sexual activity at least once a month Older men and women take longer to become sexually aroused and achieve orgasm For older women, probably the biggest obstacle to enjoying sexual relations throughout old age is the lack of a sexual partner In late adulthood, dating fills the need for companionship and sexual intimacy