Sexual Arousal and Response 33 ■ One Advantage of Being Homo sapiens Unlike other mammals, human females are continuously responsive to and available for sexual activity, indepen- RR dent of ovulation. ■ Biological Foundations for Sexual Arousal and EE Response The brain and central nervous system, including the five senses, play roles of varying importance in human sexual TT arousal and response. PP ■ Sex Hormones The sex hormones, including testosterone, the estrogens, progesterone, oxytocin, and vasopressin, play crucial roles AA in regulating sexuality. ■ The Sexual Response Cycle HH There are a number of theories regarding the events of sexual arousal and response, including Masters and Johnson’s EPOR model; Kaplan’s model of desire, CC excitement, and orgasm; and Reed’s ESP model. ■ Orgasm Men and women experience orgasm, the peak of sexual arousal, somewhat differently. The events and frequency of female orgasm vary more than those of male orgasm. ■ Sexuality and Disabilities Although they may interfere with sexual arousal and response, physical and psychological disabilities don’t necessarily preclude sexual expression. Sexual arousal, a heightened state of sexual interest and excitement, has both psychological and physical bases. There is much more to sex than the physical process of intercourse. Without the subjective feeling of pleasure, physiological arousal will not occur. However, knowledge of the physical changes that occur during sexual arousal is essential to a complete understanding of human sexuality. Sexual arousal and response are influenced by a number of factors. Of course, what one person finds sexually arousing, another might not. The patterns we will describe in the fol- lowing pages can vary from person to person, and even from experience to experience. Other biological factors and sensory processes also play significant roles in the sexual response cycle, the series of physiological processes and events that occur during sexual activity. In this chapter we focus primarily on the biology of sexual re- sponse. Later chapters will describe the influences of our emotional, social, and cul- tural needs on our sexual experiences. ONE ADVANTAGE OF BEING HOMO SAPIENS Unlike most species, humans engage in a great deal of sexual behavior that is not re- productive. But how much of our sexual response is preprogrammed, or biological, and how much is learned, either through personal experience or cultural expectations? This question has particular significance in the discussion of individual variations in sexual arousal as well as the differences between males and females. Is mating, even among animals other than humans, just about reproduction? The estrouscycle, sometimes referred to simply as estrus,is the periodic state of sexual ex- citement in the female of most mammals, excluding humans, that immediately pre- cedes ovulation and during which the female is most receptive to mating. The cycle may range in length from 18 to 35 days (Jolly, 1972), a period that is much longer than necessary simply for fertilization. It is unlikely that all of the behav- ior that occurs during this time is for the purpose of reproduction. For example, fe- males mate with many more males than is necessary for fertilization (Hrdy, 1981). Furthermore, although estrus is usually absent during pregnancy, some mammals may continue sexual activity during this time. We can be certain that no member of the genus Homo ever experienced estrus. However, we can only guess at whether any of our pre-Homoancestors were ever “in heat.” One sure sign that evolution is progress is the unique capability of human fe- Sexual Arousal: heightened state males for continuous response to and availability for sexual activity, independent of of sexual interest and excitement ovulation (see CONSIDERATIONS box). Sexual Response Cycle: physiological processes and events that occur during sexual BIOLOGICAL FOUNDATIONS FOR activity SEXUAL AROUSAL AND RESPONSE Estrous: the cycle of most female nonprimate mammals when they Which body parts do you most closely associate with sex? Although vaginal lubrica- are most sexually receptive to tion and an erect penis are more obvious physical signs of sexual arousal, it is impor- males tant to remember that the genitals are not the only organs involved in sexual arousal and response; many body systems contribute to this process. 75 76 CHAPTER 3 Sexual Arousal and Response Prime Mates Because Homo sapiens share about 98 percent of their S N genetic material with both chimpanzees and bonobos, O studying these evolutionary relatives can be useful in I T A our understanding of human behavior. R The bonobos were described by Frans de Waal in E D his 1997 book Bonobo: The Forgotten Ape. Unlike their I S chimpanzee cousins, who are known for violence, male N O domination, and sexual efficiency, bonobos are peace- C ful, egalitarian, and lead sex-filled lives in the tropical forests of the Republic of Congo in Central Africa. Ac- cording to de Waal, bonobos, not humans, appear to be the most sexual primates. They are constantly hav- ing sex of every variety, both heterosexual and homo- sexual, and with partners of all ages. Adult male bonobos grab and mouth each other’s genitals. Females regularly have sex with each other by placing their pelvises together, either face-to-face or rear-to-rear, and rubbing each other rapidly. Juvenile male bonobos suck on each other’s penises and allow adult males to fondle them. They also participate when- ever adults have sex by poking fingers and toes into the According to Frans de Waal, bonobos, not humans, appear adults’ body parts. Male and female bonobos copulate in to be the most sexual primates. They are constantly having sex of every variety, both heterosexual and homosexual, and both the typical mammalian back-to-front position and with partners of all ages. the face-to-face position, either standing or lying down with either the male or female on top. Furthermore, bonobos manually stimulate themselves and each other. What makes bonobo sexuality of interest to re- searchers is that they use sex not only for reproduction ? Why should we be interested in bonobo but also just for the fun of it. Bonobos suggest that our sexuality? idealization of private, monogamous sexual behavior might be a relatively recent deviation from our evolu- —Do you think that studying bonobos adds to our tionary heritage. Like bonobos, our ancestors may knowledge of human sexual behavior? have used sex on a daily basis to form alliances, trade —Do you think that primates and humans are too goods and favors, establish friendships, and keep the different for us to learn much from them? peace (Small, 1995). The Brain We may talk about following our hearts, but it is actually our brains that direct a great Orgasm: the peak state of sexual deal of our sexual behavior. The male erection and female vaginal lubrication may be excitement; it is marked by rhythmic contractions of the triggered by direct stimulation, but it is the brain that interprets the stimulation and pelvic floor muscles begins the process of sexual arousal and response. Motivation, desire, and behavior also are part of the thinking brain, the “executive function” that exercises volition, Cerebral Cortex: thin outer layer choice, and self-control. Even when we think we’re “behaving like animals,” very little of the brain’s cerebrum that is of our conduct is really automatic. responsible for higher mental processes including perception, Fisher and Byrne (1978) tested the arousal value of sex films on both male and fe- thought, and memory male participants. Half the viewers in their study saw soft-core films in which the actors and actresses kept their underwear on, while the rest saw hard-core films with full nu- Limbic System: a group of dity and explicit sex. To the researchers’ surprise, the participants were equally aroused interconnected deep brain regardless of how explicit the film was. In this same study, the researchers tested the role structures that especially influence motivation and of the thought process in sexual arousal. Prior to viewing the film, viewers were given emotion different story lines for the sex scenes they watched. Some were told that the people on CHAPTER 3 Sexual Arousal and Response 77 the screen were newlyweds. Others were told they were a prostitute and a client. Still FAQ: others were told the scene involved a young man and woman who had just met each other at a dance. The context had a great degree of influence on how aroused the sub- Can you have an jects became. Both male and female viewers were more aroused when they thought they orgasm just by were watching sex between two people who had just met. The prostitution and newly- thinking about sex? wed themes elicited lower levels of arousal (on both self-report and physiological mea- The brain has been called sures), even though viewers were seeing exactly the same video clip. In other words, our most important sexual arousal depended less on what people actually saw than on what they thought it meant. organ. Sexual sensations, in- While various parts of the brain are involved in sexual response and behavior, the cluding orgasm, may be two most important are the cerebral cortexand the limbic system(Figure 3.1). The triggered by sexual stimula- upper part of the brain, the cerebral cortex, is the “thinking center” of the brain, and is tion that originates in the the area of the brain responsible for sexual fantasies, desires, thoughts, and images (it is brain in the form of also responsible for nonsexual thought processes). When the brain receives arousing thoughts, fantasies, or mem- messages, the cerebral cortex interprets this sensory information and transmits mes- ories. We can become aroused by images, words, sages through the spinal cord causing an increase in heartbeat and respiration (breath- aromas, and sounds, or ing), which can alter muscle tension (or myotonia), send blood to the genitals, and without any outside sensory increase skin sensitivity. Your ability to consciously identify these physical changes can stimulation whatsoever in actually contribute to your sexual arousal. the form of thoughts, fan- The limbic system, located within the cerebrum in the area below the cortex, con- tasies, or memories. Your sists of the thalamus,the hypothalamus,and other structures important to sexual arousal. brain, glands, nervous sys- This complex group of structures controls our emotions, motivations, memories, and tem, circulatory system, and behavioral drives (Everitt, 1990). In 1939, Heinrich Klüver and Paul Buey first demon- reproductive system are all strated the importance of the limbic system in regulating sexual behavior in animals. involved in your sexual fan- When they destroyed certain areas of the limbic system, it tamed wild monkeys, but also tasies. The fact that many triggered an increase in the frequency, intensity, and ability to perform sexual behaviors. people become sexually aroused during sleep, some- Sex and the Senses times even to the point of orgasm, is one important The five human senses—touch, sight, smell, hearing,and taste—all contribute to sexual sign that the brain contains arousal and to the sexual response cycle. However, the same sensory stimulation can all the information neces- evoke different responses in different people. In one study (Herz & Cahill, 1997), re- sary to produce sexual arousal (at least sometimes). searchers asked men and women to rate the importance of olfactory (smell), visual (sight), auditory (sound), and tactile (touch) information on their sexual response. Males rated visual and olfactory information as equally important in the selection of a Limbic Lobe Cerebral cortex Fornix Thalamus Pituitary Hypothalamus gland Hippocampus Amygdala FIGURE 3.1 The limbic system of the brain, associated with emotion and motivation, is important in human sexual function. 78 CHAPTER 3 Sexual Arousal and Response lover, while females considered olfactory information to be the single most important FAQ: variable; in the words of an old television commercial, “If he stinks, forget it!” (The ad What are erogenous was for deodorant, of course!) When considering what sense had the most negative ef- zones? fect on sexual desire, females rated body odor highest; males regarded smells as being much more neutral stimuli for sexual arousal (Herz & Cahill, 1997). Nerve endings are unevenly distributed throughout the Touch The skin is the largest organ in the human body. Stimulating an area of the body, causing some areas to be more sensitive to touch body by touch is probably the most frequent method of sexual arousal and has the than others. Those body most direct effect on sexual response. A soft kiss on the lips, a tender touch on the areas most sensitive to tac- arm, or a gentle lick on the ear all can be highly arousing, as can stroking a penis or tile stimulation are some- the brushing of lips across a nipple. times referred to as erogenous zones. The Sight Visual information plays a major role in sexual arousal. The fashion, diet, and erogenous zones of the cosmetic industries, as well as the market for erotic photographs and movies, reflect human body include the the emphasis our society places on visual arousal. Animals other than humans also use genitals, buttocks, anus, per- visual cues to signal sexual attraction. The peacock’s plumage and the lion’s mane may ineum, breasts, and inner be the animal kingdom’s version of a low-cut blouse or skin-tight jeans. surfaces of the thighs, neck, Studies show that men and women respond differently to visual stimulation. In ears, navel, armpits, and mouth. As you have already one study, 54 percent of the men but only 12 percent of women became erotically learned, areas that may be aroused when they were shown photos and drawings of nudes (Reinisch, 1991). extremely sensitive in one person may provoke no re- Smell Recent research indicates that the sense of smell may control human sexual ac- action, or even a negative tivity, compatibility, group behavior, and other social activity, just as it does in animals reaction, in another. The (Stern & McClintock 1998). In Chapter 2 we introduced pheromones, naturally pro- only way to determine the duced chemicals that affect behavior through the sense of smell. The pheromones pro- location of your partner’s duced by a queen bee inhibit the sexual development in other females, who then become erogenous zones is through workers. Male mice use pheromones to promote the sexual development of nearby fe- experimentation. males, and if a sow or a cow in heat smells the pheromones contained in male urine she will take a mating stance (see CROSS-CULTURAL PERSPECTIVES box). Only recently has the presence of human pheromones been confirmed. One study evaluated the effect of synthesized male pheromones placed in an aftershave lotion on six behaviors in men: petting, formal dates, informal dates, sleeping next to a romantic partner, sexual intercourse, and masturbation. Pheromone users had increased rates of intercourse, sleeping with romantic partners, petting, and informal dates; there was no effect on masturbation or formal dates (Cutler et al., 1998). Although the full ex- Erogenous Zones: parts of the body that are especially sensitive tent to which pheromones influence human sexual behavior is unknown, researchers to stimulation suspect that different pheromones may control different activities. S E V I T C E P Sex Scents S R E Olfactory preferences are determined in men carry handkerchiefs in their armpits P large part by culture. Women in some soci- during festivals and offer these as tokens to L A eties use their vaginal secretions as a per- women they invite to dance. In contrast, in R fume, rubbing some behind the ear or on America, most people think that the smell U T the neck to attract and arouse sexual part- of a moist vagina or sweaty armpit would L U ners. Sweat is an almost universal ingre- not be appealing, and indeed many people C dient in love potions throughout the world. regularly use deodorants to conceal these - Touch is probably the most S In parts of the Balkans and Greece some odors from a dating partner. frequent method of sexual S O arousal and has the most direct R effect on sexual response. C CHAPTER 3 Sexual Arousal and Response 79 FAQ: What smells arouse men the most? What do women like best? A research study measured changes in penile response and vaginal blood flow in re- sponse to different odors (Hirsch, 1998). In contrast to what the floral and perfume Visual cues play a major role in sexual Our sense of hearing influences sexual industries would have us be- arousal. arousal and response. Sex and love have lieve, the study reported that been the inspiration for music and music is often used to set a romantic mood. the odors found most arous- ing were not flowers or cologne. The aromas that Hearing Our sense of hearing also influences sexual arousal and response. For some, evoked the greatest response romantic music may set the mood (see CONSIDERATIONS box). Others may be in men were pumpkin pie sexually aroused when their lovers “talk dirty” or moan during lovemaking. and lavender, while women Tiny hair cells in the inner ear vibrate to transmit sounds. By examining these were most stimulated by the smell of licorice coated cells, researchers have found women’s ears to be more sensitive than men’s. Females candy (Good & Plenty), cu- hear high-pitched sounds better than males while men are more comfortable with cumbers, and baby powder. louder sounds than women (Bloom, 1998). None of the odors tested was In one study, male college students were shown 60-second erotic videos both with found to inhibit the sexual and without the accompanying audio. There was a significant positive correlation be- desire of men. However, tween male sexual arousal and sound, as measured by penile plethysmograph and self- smells that inhibited vaginal report (Gaith & Plaud, 1997). blood flow in women in- Another study found that a male partner’s silence during lovemaking inhibited the cluded cherries, charcoal- female partner’s sexual response (DeMartino, 1990). However, silence might be barbecued meat, and men’s preferable to some other sounds, such as your partner burping during an embrace or colognes. This same re- the ringing of the phone. Many people find the sound of the words “I love you” to be searcher theorized that odors might act directly on the link the most arousing of all. between the olfactory sense and the brain’s limbic system Taste The role of taste in human sexual arousal has not been fully investigated. (Hirsch, 1998). Some individuals may be sexually aroused by the taste of vaginal secretions or seminal fluid. It is possible that genital secretions contain chemicals that have an arousing ef- fect, or it may be the psychological association of the flavors with past sexual pleasure that cause the excitement. Aural Sex Whether it is Ravel’s “Bolero” or Barry White, music “oohing” and “aahing” herself into the throes of ec- S N can simulate or stimulate sexual activity. Sounds of ec- stasy “may stand as the most prominent signifier of fe- O stasy have been a staple of pop music since the 1960s. male pleasure in the absence of other more visual I AT Songs that contain sounds of female orgasm include: assurances. Sounds of pleasure . . . seem almost to flout R Marvin Gaye’s “You Sure Love to Ball” (1973), Donna the realist function of anchoring body to image, E D Summer’s “Love to Love You Baby” (1975), Duran halfway becoming aural fetishes of the female pleasures I S Duran’s “Hungry Like the Wolf” (1982), Prince’s “If we cannot see” (Wiliams, 1989, pp. 122–123). N O The Kid Can’t Make You Come” (1984), and Prince’s ? Is there a song that almost always puts you in C “Orgasm” (1995). Sounds of male sexual pleasure are the mood for love? rarely heard in music. Perhaps this is because sound may be the only indication that some men have of —What sounds, or words, do you like most, and women’s orgasm, whereas women have more obvious least, to hear when making love? physical evidence of a male partner’s climax (Corbett & —Can you think of a sound that would be an Kapsalis, 1996). The disembodied female vocalist absolute turnoff? 80 CHAPTER 3 Sexual Arousal and Response In a 1980 study, Farb and Armelagos noted that the tradition of giving a box of chocolates on Valentine’s Day might have arisen because chocolate contains phenylethyl- amine (PEA), a chemical believed to produce a lovelike sensation. Then again, foods such as salami and cheddar cheese have even higher levels of PEA—although few people would consider a deli sandwich an appropriate romantic gift. Chocolate also contains cannabinoids, the compound responsible for marijuana’s high, although the amount isn’t remotely close to that found in marijuana. In addition, the stimulants caffeine and theo- bromine are hidden in those delicious chocolate bars. The fat and sugar in chocolate can- dies are also likely to increase the volume of the brain chemical serotonin, which among other functions is responsible for making us feel good. SEX HORMONES The word hormone comes from the Greek horman, which means to arouse, to excite, to urge—which is exactly what our hormones do. Hormones, chemical substances se- creted by your endocrine system (Table 3.1) arouse, excite, and influence your sexual- ity throughout your life. The endocrine system is a separate control system for the body, apart from the nervous system, and is comprised of ductless glands that release secretions directly into the bloodstream. There are several different types of hor- mones. For example, if you are in a stressful situation, hormones are deposited into the bloodstream by the adrenal, pituitary, thyroid, and other glands, resulting in an in- crease in heart rate, muscle tension, blood pressure, and perspiration. Sexual arousal works in a similar way. When you are aroused by a sexual stimulus, your endocrine system is activated, hormones are secreted, and changes occur in your body. Although androgens (from the Greek andros, for male) are commonly referred to as male sex hormones and estrogen (from the Greek oistros,for gadfly or frenzy) as the female sex hormone, neither hormone is gender exclusive. The difference is how much hormone circulates in the bloodstream. Testosterone Testosterone, the most important androgen, is secreted in small amounts by the adrenal glands in both males and females and in much larger amounts by the testes (Figure 3.2 on page 82). On average, men have at least 10 times more testosterone than women do (Worthman, 1999). Women produce testosterone in their ovaries and adrenal glands. The brain can convert testosterone into estradiol (a form of estrogen) so that the so-called male hormone becomes the so-called female hormone. In women, testosterone increases the flow of estrogen to the center of the brain that con- trols sexual motivation and drive. Each of us inherits a certain baseline level of testos- terone, but testosterone levels are not constant; they fluctuate on a daily cycle and in response to daily events. Research has shown that testosterone levels change in re- sponse to physical, emotional, and intellectual challenges (Booth et al., 1992; Booth et al., 1995). On average, testosterone levels of U.S. males tend to go into a steady decline after age 20; the hormone’s concentration in the blood decreases by about 30 percent by the time a male reaches 80. In the developing human fetus, testosterone provides the early signal for the de- velopment of a male body, and it is responsible for the primary differences in male and female appearance. Even in adults, an imbalance in testosterone levels can alter body shape. It is clear that testosterone interacts with the nerve cells that make up the brain. We are not certain, however, what role the hormone plays in the development of per- sonality and behavior (Blum, 1997). A decrease in testosterone often is associated with a decline in male sexuality. In an attempt to restore their virility, in the 1920s physicians actually grafted monkey testes onto aging men (Blum, 1997). However, this pattern of hormone decline with aging is not universal. A cross-cultural study (Worthman, Beall, & Stallings, 1997) in- dicated that male subjects in Bolivia had a modest decrease in testosterone levels after CHAPTER 3 Sexual Arousal and Response 81 TABLE 3.1 Hormones of the Reproductive System Hormone Source Regulation of Primary effects secretion Gonadotropin-releasing Hypothalamus Males: inhibited by testosterone Stimulates FSH secretion, LH hormone (GnRH) and possibly by inhibin. synthesis Females: GnRH pulse frequency increased by estrogens, decreased by progestins Follicle-stimulating hor- Anterior pituitary Males: stimulated by GnRH, Males: stimulates spermatoge- mone (FSH) inhibited by inhibin. nesis through effects on sus- Females: stimulated by GnRH, tentacular cells inhibited by inhibin Females: stimulates follicle development, estrogen production, and oocyte maturation Luteinizing hormone Anterior pituitary Males: stimulated by GnRH. Males: stimulates interstitial (LH) Females: production stimulated cells to secrete testosterone by GnRH, secretion by the Females: stimulates ovulation, combination of high GnRH formation of corpus luteum, pulse frequencies and high and progestin secretion estrogen levels Androgens (primarily Interstitial cells of Stimulated by LH Establish and maintain sec- testosterone and dihy- testes ondary sex characteristics and drotestosterone) sexual behavior; promote mat- uration of spermatozoa; in- hibit GnRH secretion Estrogens (primarily Granulosa and thecal Stimulated by FSH Stimulate LH secretion (at estradiol) cells of developing high levels); establish and follicles; corpus maintain secondary sex char- luteum acteristics and sexual behavior; stimulate repair and growth of endometrium; increase fre- quency of GnRH pulses Progestins (primarily Granulosa cells from Stimulated by LH Stimulate endometrial growth progesterone) midcycle through and glandular secretion; functional life of reduce frequency of GnRH corpus luteum pulses Inhibin Sustentacular cells of Males: stimulated by factors Inhibits secretion of FSH and testes and granulosa released by developing sperma- possibly of GnRH cells of ovaries tozoa. Females: stimulated by devel- oping follicles SOURCE:Martini, 2000, p. 1057. age 30, with hormone levels remaining relatively stable after that time. On the other hand, testosterone levels in Tibetan males do not peak until the late 50s and then fall precipitously during the 60s and 70s. Neither the cause nor the possible significance of these variations is known. There is as much controversy about the connection between blood levels of testosterone and measures of sexual desire, or libido,as there is about the connection Libido: sexual desire 82 CHAPTER 3 Sexual Arousal and Response Gonadotropic-releasing hormones (GnRH) Tuberal region of the hypothalamus Gonadotropic-stimulating hormones (FSH,LH) Anterior pituitary Leydig cells of the testes Testosterone FIGURE 3.2 The Production and Release of Testosterone in Males. Stimulation of the tu- beral region of the hypothalamus causes the release of gonadotropic-releasing factor, which causes the anterior pituitary to secrete luteinizing hormone (LH). LH then travels through the bloodstream to stimulate the Leydig cells of the testes to manufacture and release testosterone. between testosterone and aggression (see CONSIDERATIONS box). Researchers at the Yerkes Primate Research Center at Emory University found that when male mon- keys win a contest their T-levels increase for about 24 hours; the T-levels of the losers remain lower for even longer than a day. However, if the loser simply sees a sexually receptive female, his testosterone level shoots back up. “So now you know [what ac- counts for] the popularity of strip bars: they’re where male losers go to get their T back up,” claimed one of the Yerkes researchers (Wallen, 1997 quoted in Tierney, 1998, p. B1). One of the best overviews of research on testosterone, Heroes, Rogues, and Lovers (Dabbs, 2000), portrays testosterone as a mixed blessing, with both good and bad fea- tures. According to Dabbs, high levels of testosterone (in both men and women) lead to more sexual activity, which of course helps make more babies. But it also leads peo- ple to become more fickle and restless, so they are less likely to stay around to nurture and support the children. Remarkably, nature seems to have instilled some mecha- nisms to make parents stick around. Dabbs reports that testosterone levels are high in single men, drop when the men get married, and drop even more when their wives CHAPTER 3 Sexual Arousal and Response 83 “Roid” Rage When most people hear the word steroid they think of S N anabolic steroids, the drugs that bodybuilders and O other athletes take in an effort to inflate their strength I T A and bulk. These drugs usually are a synthetic version of R testosterone. When scientists first created synthetic E D testosterone it was thought to be a “wonder drug” that Photograph 3-F: I S would keep men young and strong well into old age. pumped up angry N O We now know better. looking athlete C People, usually athletes, take anabolic steroids to improve their physical appearance and their perfor- mance. Steroids can also cause heart attacks, strokes, liver injury, damage to the reproductive system, and personality changes (Todd, 1987). It has been reported that steroid use in adolescents causes premature clos- Anabolic steroids, taken by some men to improve their phys- ing of the epiphyseal growth plates in the skeletal sys- ical appearance and performance, can cause heart attacks, tem, leading to shorter stature (Yesalis, Wright, & strokes, liver injury, damage to the reproductive system, and personality changes. Bahrke, 1989). Steroids also have a reputation for making men vi- olent and aggressive. Violent criminals tend to have higher-than-average levels of testosterone. Separate Other studies look to psychosocial factors that may studies in men’s and women’s prisons have found that bring about the aggression attributed to steroids (Sharp murderers have higher levels of testosterone than & Collins, 1998). For example, the effects of previous other convicts, and, more generally, violent criminals psychiatric history, environmental and peer influence, have higher testosterone levels than nonviolent con- and individual expectations remain unclear. One re- victs. Although several studies have linked high testos- searcher hypothesizes that behavior we sometimes at- terone levels (T-levels) to aggressive behavior in both tribute to steroid abuse is actually the “nasty personality animals and humans, others question the link between of some athletes reinforced by a sports culture that glo- testosterone and aggression. Only three studies have rifies the physical response” (Yesalis, 1997). reported a link between aggression or adverse overt be- ? Do you know anyone who uses anabolic havior and anabolic steroid use (Bahrke, Yesalis, & steroids? Wright, 1997). Studies administering moderate doses of testosterone for clinical purposes reveal essentially —Have you ever used or considered using no adverse effects on male sexual and aggressive behav- steroids? ior (Ibid., 1997). have babies. In one study, expectant fathers who held a baby doll wrapped in a blanket experienced a statistically significant drop in testosterone within just half an hour (Storey et al., 2000). Men who remain single throughout life have high testosterone levels (but not as high as those who marry and then divorce). In general, men with high levels of testosterone are more likely to seek out sex and aggression, but are less reliable providers for their wives and children. In numerous species (including our own), males with low testosterone levels live longer (Worthman, 1999). Testosterone level also affects the workplace—or is it the other way around? (See CONSIDERA- TIONS box). There may also be a link between T-levels and libido in women (Crenshaw, 1996; Hutchinson, 1995; Rako, 1996). At the onset of menopause, a woman’s ovaries and adrenal glands begin to produce less testosterone and other androgens. As a re- sult, the amount of testosterone circulating in the body is reduced by at least half. While some women may react to this change by experiencing a noticeable drop in sexual desire, others may not notice any difference. One study showed a decrease in Anabolic Steroids: synthetic sexual desire among premenopausal women whose ovaries were surgically removed derivative of testosterone