There are many powerful influences on our sexuality. Here we discuss three of the biggest influences: hormones, ethnicity, and religion.

Hormones

As we discussed in Chapters 4 and 5, hormones have a powerful effect on our bodies. The various endocrine glands secrete hormones into the bloodstream, which carries them throughout the body. The most influential hormones in sexual behavior are estrogen and testosterone. Both men and women produce these hormones, though in different quanti­ties. For example, in men testosterone is produced in the testes and adrenal glands, and in women testosterone is produced in the adrenal glands and ovaries. Even so, men pro­duce much more testosterone than women: men produce 260 to 1,000 nanograms per deciliter of blood plasma (a nanogram is one-billionth of a gram), whereas women pro­duce around 15 to 70. The amount also varies and decreases with age.

^ INFLUENCES ON SEXUALITY Подпись: 35 30 25 20 15 10 5 0 ^ INFLUENCES ON SEXUALITY Подпись: Figure 10.1 Number of sexual partners reported by females and males, 18-59 years old. Source: National Health and Social Life Survey, as re-ported in Laumann et al., 1994.

"How many sexual partners have you had?" (18-59 years old)

Подпись:Подпись:Подпись:Подпись:During menopause, women’s estrogen levels fall, which can lead to slower growth in the vaginal cells, resulting in thinner vaginal walls, vaginal dryness, and decreased vagi­nal sensitivity. Despite this decrease in estrogen, testosterone levels often remain con­stant, which may result in an increase in sexual desire even though the above physical changes can negatively affect sexual functioning.

Although controversial, hormone replacement therapy (estrogen or a combination of estrogen and progesterone) can help alleviate some of these physical changes and in­crease sexual desire (see Chapter 4 for more information about hormone replacement therapy). In men, decreases in testosterone can lead to lessening sexual desire and de­creases in the quality and quantity of erections. We will discuss aging and sexuality more later in this chapter.

In most animals, the brain controls and regulates sexual behavior chiefly through hormones. In humans, hormones have an enormous effect on sexual behavior as well, but people are also very strongly influenced by learned experiences and their social, cul­tural, and ethnic environment.