3-03 Variations In Sexual Behaviors

Front 1

Objective

Compare the mating preferences of men and women.

Back 1

Men are more likely than women are to seek multiple sex partners, especially for short-term encounters. Women are more likely than men to be concerned about a potential mate’s earning ability, whereas men are more likely to be concerned about a mate’s youth. Men usually show greater jealousy than women at any indication of sexual infidelity.

Front 2

Objective

Explain these preferences from an evolutionary standpoint.

Back 2

From the evolutionary standpoint of spreading one’s genes, men can succeed by adopting one of two strategies: Be loyal to one woman and devote their energies to helping her and her babies, or mate with many women and hope that some of them can raise the babies without their help. In contrast, a woman can have no more than one pregnancy per nine months, regardless of her number of sex partners. So evolution may have predisposed men, or at least some men, to be more interested in multiple mates than women are.

One objection to this argument is that a woman can gain certain benefits from having multiple sex partners. If her husband is infertile, mating with another man could be her only way of reproducing. Also, another sexual partner may provide her with valuable gifts and may be kind to her children. She also has the possibility of “trading up,” abandoning her first mate for a better one. So the prospect of multiple mates may be more appealing to men, but it can have some advantages for women too.

Men and women both prefer a healthy, intelligent, honest, physically attractive mate. Women have some additional interests that are not prominent for men. For example, most women prefer mates who are likely to be good providers. That tendency is strongest in societies where women have no income of their own. However, in all known societies, women are more interested in men’s wealth and success. According to evolutionary theorists, the reason is clear: while a woman is pregnant or taking care of a small child, she needs help getting food and other requirements. Evolution would have favored any gene that caused women to seek good providers. Related to this tendency, most women tend to be cautious during courtship. Even if a man seems to be very interested in her, a woman waits for a while before concluding that he has a strong commitment to her. She would not want a man who acts interested for a while and then leaves when she needs him.

Men tend to have a stronger preference for a young partner. An evolutionary explanation is that younger women are more likely than older women to be fertile, so a man can spread his genes beset by mating with a young woman. Men remain fertile into old age, so a woman has less need to insist on youth. A contrary interpretation is that women also prefer young partners when possible, but in many societies, only older men have enough financial resources to get married.

Why might men be more jealous about wives’ sexual infidelities than women should be about husbands’ infidelities? If a man is to pass on his genes—the key point in evolution—he needs to be sure that the children he supports are his own. An unfaithful wife threatens that certainty. A woman’s children are necessarily her own, and so she has no similar worry.

Front 3

Objective

Discuss the hormonal mechanism underlying CAH.

Back 3

Congenital adrenal hyperplasia (CAH) is a condition in which there is overdevelopment of the adrenal glands from birth. This causes larger amounts of testosterone to be secreted. In genetic females, the effect is the masculinization of the external genitals.

Front 4

Objective

Identify the two classes of hermaphrodites.

Back 4

Individuals whose genitals do not match the usual development for their genetic sex are referred to as hermaphrodites. The true hermaphrodite, a rarity, has some normal testicular tissue and some normal ovarian tissue—for example, a testis on one side of the body and an ovary on the other. Individuals whose sexual development is intermediate or ambiguous are called intersexes or pseudo-hermaphrodites.

Front 5

Objective

Describe the mechanism that gives rise to androgen insensitivity.

Back 5

Certain individuals with an XY chromosome pattern have the genital appearance of a female. This condition is known as androgen insensitivity. Although such individuals produce normal amounts of androgens (including testosterone), they lack the androgen receptor that enables the hormones to activate genes in each cell’s nucleus. Consequently, the cells of the body are insensitive to androgens, and development proceeds as if the level of testosterone and related hormones were very low. This condition occurs in various degrees, resulting in anatomy that ranges from a smaller than average penis to genitals like a normal female. In some cases, there is no reason to suspect that the person is anything other than a normal female—at least until the individual reaches puberty. Then, in spite of breast development and broadening of the hips, menstruation does not begin because the body has internal testes instead of ovaries and a uterus (the vagina is short and leads to nothing). Also pubic hair is sparse or absent because it depends on the presence of androgens in females as well as in males.

Front 6

Objective

Cite possible evidence for the role of genetics, hormones, prenatal events and brain anatomy in sexual orientation.

Back 6

Genetics
Hormones
Prenatal Events
Brain Anatomy

See study guide.

Front 7

gender identity

Back 7

How we identify sexually and what we call ourselves

Front 8

congenital adrenal hyperplasia (CAH)

Back 8

Genetic defect in cortisol production that leads to overstimulation of the adrenal glands and therefore extra testosterone production; when that condition occurs in a female fetus, she becomes partly masculinized

Front 9

hermaphrodite

Back 9

Individual whose genitals do not match the usual development for their genetic sex

Front 10

intersex (pseudo-hermaphrodite)

Back 10

Individuals whose sexual development is intermediate or ambiguous

Front 11

androgen insensitivity (testicular feminization)

Back 11

Condition in which someone with an XY chromosome pattern is partly or fully insensitive to androgens and therefore develops a female external appearance