The Male Brain
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by their clans or tribes: Freeman 2009a found culture shapes the brain’s response.
score and regained some respect: Stanton 2009 found that high testosterone levels are associated with dominance behavior and pursuit of status in men, and that men’s testosterone levels rise after winning dominance contests. This positive feedback to the brain primes future dominance behavior. For more on hormones and social status in males, see Sapolsky 1986 and 2005, Becker 2008b, Hermans 2006 and 2007 and 2008, Rubinow 2005, Van Honk 2005 and 2007, and Viau 2002.
in front of his peers: For more on the brain, social value, social learning, and self-confidence, see Behrens 2008 and Eme 2007.
establish and maintain social hierarchy: For more on the brain, social hierarchy, dominance, and subordination, see Freeman 2009. For more on teen boys’ behavior and hormones, see Olweus 1988 and Archer 2006.
and not afraid to fight: Sell 2009 found that males begin to show displays of hostile intent, such as angry facial expressions, in the teen years, and that males learn to quickly assess the strength and fighting spirit of other males just by looking at their faces.
become hard to live with: Olweus 1980 and 1988 found that teen boys have increased irritability.
his team couldn’t lose: See Becker 2008a for more on the male brain and sex differences in excitement and dopamine systems. Salvador 1987, 2003, and 2005 found that during competition, a male’s testosterone increases and, depending on the outcome and the importance of the event for the male, remains high for winners and drops for losers. Suay 1999 studied judo competitors. In those athletes larger increases in testosterone were highly correlated with looking angry while fighting, responding to a challenge, and being a violent competitor. For more on competition, brain, and testosterone, see Gatzke-Kopp 2009, Kahnt 2009, Sallet 2009, Kraemer 2004, and Berman 1993.
losing, even in sports spectators: Bernhardt 1998 found that even the vicarious experience of winning—e.g., being a fan whose team wins—leads to increased testosterone levels.
in favor of their own: Weisfeld 1999. See Levinson 1979 for more on psychological stages of development in adolescent males.
seek autonomy from his parents: Weisfeld 1999 and 2003. Fischer 2007 found that a high level of gender-role conflict in adult men was associated with parents’ overprotection in teen years.
they strike out on their own with bravado: Spear 2004.
new ideas in every generation: Spear 2004 and Nelson 2005.
willing to do risky things: Nelson 2005. Steinberg 2007 found that adolescents and college-age individuals take more risks than children or adults do, which is reflected in statistics on automobile crashes, binge drinking, contraceptive use, and crime.
consequences of unsafe, impulsive choices: Steinberg 2007. Teicher 2000 found that the part of the brain that allows and encourages us to delay gratification and inhibit impulsive action—the PFC—won’t be finished until later in the teen years and that it develops even later in boys’ brains than in girls’.
in a video driving game: Steinberg 2004 found that the presence of peers more than doubled the number of risks teenagers took in a video driving game. Dahl 2008 says that sleep deprivation is rampant among adolescents and that the consequences of insufficient sleep (sleepiness, lapses in attention, susceptibility to aggression, and synergy with alcohol) appear to contribute significantly to driving risks in teens.
know what they’re doing: Eaton 2008 found that in the United States, 72 percent of all deaths among persons age 10–24 result from four causes: motor-vehicle crashes, other unintentional injuries, homicide, and suicide. The 2007 national Youth Risk Behavior Survey (YRBS) indicated that many high-school students engaged in behaviors that increased their likelihood of death from these four causes.
biologically ready to handle independence: Doremus-Fitzwater 2010 found that biological changes in the brain’s motivational and reward-related regions increase teens’ peer-directed social interactions, risk taking, novelty seeking, and drug and alcohol use relative to adults. For more on how teens’ sleep deprivation influences risky peer interactions, see Dahl 2008.
prefrontal cortex (PFC)—is like a brake: Steinberg 2004 and 2007.
boys until their early twenties: Giedd 1996 and 2009.
mother’s body, but also by her smell: Savic 2001 and Weisfeld 2003 found that the odor of genetically related family members is not romantically attractive. For more on MHC genes and odorous attraction, see Garver-Apgar 2006, Wedekind 1995, and Yamazaki 2007.
to have fleeting sexual fantasies: Campbell 2005 studied schoolboys age 12–18. The study found spontaneous nocturnal emission, secondary sexual characteristics, and salivary testosterone correlated with age at first sexual fantasies, noncoital sexual behavior, and coitus. They found first erection at an average age of 10.75 years, first sexual fantasy at 12.66 years, first spontaneous nocturnal emission at 13.02 years, and adult levels of blood testosterone at 17.2 years. Carlier 1985 found that boys’ testicle size correlated best with first ejaculation.
when boys begin frequent masturbation: Korkmaz 2008 found that over 90 percent of 16-year-old boys masturbated and 98 percent reported that they liked it and thought it was natural. However, some felt guilt, fear of harming one’s body, or shame. Some boys felt sexually inadequate when they compared themselves with their peers, feeling they were not as attractive to girls. For more on sexual behavior in teen boys, see Giles 2006, Auslander 2005, and Browning 2000.
to three times a day: Tanagho 2000.
less than one time per day: Korkmaz 2008. Gerressu 2008a found that 95 percent of men and 71 percent of women masturbated. And one consistency across all studies was the large gender difference in the prevalence and frequency of masturbation—both being much greater in males. For more on sexual frequency in males and females, see Kontula 2002, Hyde 2005, Dekker 2002, Pinkerton 2002, Langstrom 2006, Giles 2006, and Laumann 1999b.
at the first opportunity: Tanagho 2000.
finally came to “do it”: Adolescents are faced with many developmental tasks related to sexuality, such as forming romantic relationships and developing their sexual identities. Almost half will engage in vaginal sexual intercourse by the end of high school. For more on puberty and sexual development, see Eaton 2008 and Auslander 2005.
THREE: THE MATING BRAIN: LOVE AND LUST
The Mating Brain: Love and Lust: For a review on similarities and differences in the mate preferences and choices of women and men, see Geary 2004 and Young 2008.
lit up like a slot machine: For more on brain circuits for male courtship behaviors, see Pfaff 2002, Fernandez-Guasti 2000, Wu 2009, Maner 2007b, and Manoli 2006.
of his ancient mating brain: Voraceck 2006 found that the ultimate goal of female physical attractiveness is to elicit male sexual arousal. They found that males focused more on waist-to-hip ratio in women they saw moving and more on bust size in women who were stationary. In humans, the nucleus of the preoptic area of the hypothalamus is two to two and a half times larger in the male brain compared with the female. And Welling 2008 found that changes in testosterone levels contribute to the strength of men’s attraction to femininity in women.
in men across all cultures: Singh 2002.
mate-detection circuit was visual: Tsujimura 2009 found that in the non-intercourse video clip, gaze time for the face and body of the actress was significantly longer among men than among women.
mating brain read Nicole right: Amador 2005 found that both sexes place high value on traits like dependable character, emotional stability/maturity, and pleasing disposition, as well as mutual attraction and love. Women in the study placed higher emphasis on ambitious/industrious character, similar educational background, and good financial prospects. Men cared more about the woman’s fitness and good health, good cooking/housekeeping skills, and good looks.
cute and looked harmless enough: Maner 2008 and Shoup 2008. For more on mating judgments of men versus women, see Gangestad 1993 and 2000.
&
nbsp; cues as Ryan and Nicole: Eibl-Eibesfeldt 1972.
not out of his league: Bateson 2005 and Alpern 2005 found that both men and women become less choosy over time, as the highest-ranking and most fit and attractive individuals pair off first. This means that for a male to be chosen by her as the best, all he has to do is outshine the other males he is being compared with on the specific characteristics she is focusing on.
“I’m here to watch you”: O’Hair 1987 and Farrow 2003.
wrong with meeting those expectations: O’Hair 1987 and Haselton 2005.
with the highest-pitched voices: Apicella 2009. Sokhi 2005 found that female and male voices activate different regions of the male brain. Hughes 2008 and Pipitone 2008 found that a woman’s voice attractiveness varies across the menstrual cycle.
go weak in the knees: And Roney 2008 found that women are more attracted to men’s masculine characteristics, like jutting jaw and large muscles, during the ovulatory phase of the menstrual cycle.
potentially a good genetic match: Savic 2001b found that men are most attracted to the scent of women who are genetically different from them. And according to Lundstrom 2006, women who are on the “pill” or hormonal birth control do not make the same pheromones or have the ovulatory-phase rise in testosterone derivatives like androstenedione that stimulate the sweat glands to produce those feminine “come-hither” pheromones.
give birth to sickly offspring: Alvarez 2009.
best to each other: Wedekind 1995. Yamazaki 2007 found that dissimilar gene-type MHC emits special body odors that underlie mate choice and familial recognition, which helps make sure that inbreeding with parents and siblings does not occur. For more on brain responses to pheromones, see Hummer 2010, Mujica-Parodi 2009, and Prehn-Kristensen 2009.
and not even known why: Li 2007 says that people’s odors can increase or decrease their likeability rating. Furthermore, according to Berglund 2006 and Sergeant 2007, gay males’ and gay females’ brains respond positively to same-sex pheromones. They dislike those odors of the opposite sex. For more on mating and pheromones, see Savic 2001a and 2009 and Zaviacic 2009.
about hygiene; it’s about genes: Weisfeld 2003 and Olsson 2006. Havlicek 2009b found that olfactory and visual channels may work in a complementary way in mate attraction to achieve an optimal level of genetic variability.
could talk to her about: Keverne 2007 suggests that a male’s ability to find a fertile mate requires some serious strategic maneuvering and that for human males, these reproductive strategies are complex and embedded in the social structure and hierarchies of society. So success in human males usually depends more on intelligent behavior than on hormones or odors.
tension between them was palpable: Roney 2007 found that a man’s testosterone goes up just from talking to a woman.
secretly sent to their brains: Gallup 2008 and Hughes 2007 found that kissing is a mate-assessment device. Wyart 2007 found that testosterone and its metabolites are found in male saliva, semen, and sweat—and they smell, and perhaps taste, delicious to a woman when she is ovulating. While females find the masculine odor attractive, heterosexual males dislike it. For more on pheromones and mating, see Bensafi 2003 and Walter 2008.
center in a woman’s brain: Muir 2008 suggests that a man’s excretions could be absorbed by a woman during kissing, touching, and skin-to-skin body contact and thereby affect her brain.
Nicole was being so cautious: Hill 2002 found women more cautious about moving toward sex too soon and men needing less of a sense of emotional investment in the relationship before having sex.
up to three times longer: Buss 1993.
anything, least of all sex: Roese 2006 found that women regret having sex early in the dating relationship more than men do.
offspring he’s likely to have: Buss 1993 found that men’s wanting sex with many women has likely been evolutionarily selected for in males.
of education or financial independence: Buss 2005 and Jensen-Campbell 1995.
and was willing to invest: Griskevicius 2007 found specific mating goals increased men’s willingness to spend money on conspicuous luxuries for women. They say that romantic motives produce highly strategic and sex-specific self-presentations. And Klapwijk 2009 found that generosity serves the important purpose of communicating “trust.”
males who bring them meat: Gomes 2009.
men, sex often comes first: For more on gender differences in love, commitment, and sex, see Roese 2006, Sprecher 2002, Keverne 2007, Loving 2009, McCall 2007, Geary 2000, and Buss 1993.
side-blotched lizard (Uta stansburiana): Bleay 2007.
“How can I pick a blue-throat?”: Humans have a mating system scientists refer to as mild polygyny—multiple partners combined with a variable commitment to male parenting. Andrews 2008 found a sex difference in detecting infidelity—men are better at it. Atkins 2001a found that 20 percent to 25 percent of the married American population had had episodes of infidelity. Kontula 1994 found that in Finland, 52 percent of the men and 29 percent of the women reported episodes of infidelity in their lifetimes. They found that men reported being less emotionally involved than women with their infidelity partners, whereas the women seemed to connect both emotionally and sexually.
aggressively reject all other females: Gobrogge 2007 found that passionate mating changes the male brain biologically forever and that it leads pair-bonded male prairie voles to reject new fertile females. They found that it is an interaction between dopamine and vasopressin that results in pair bonding in the male brain’s hypothalamus and nucleus accumbens, NAc. For more on hormones, genes, and pair bonding, see Winslow 1993, Carter 1998, Liu 2001 and 2003, Lim 2004c, and Young 2009a. (In the female brain, it is oxytocin and dopamine that interact to produce pair-bond formation.)
preference for this one female: For more on sex and partner preference in mammals, see Carter 1998 and Young 2008.
bond with their sexual partners: Liu 2001 found that when experimenters gave a chemical to block the vasopressin receptor, it blocked the intercourse-induced pair bonding in the males.
in their brains couldn’t merge: For more on hormones in the brain, sex, and pair bonding, see Young 2008 and 2009b, Carter 1998, Becker 2008b, Wang Z. 2004, and Pfaff 2002.
vole, he, too, became monogamous: Lim 2004c experimentally induced pair-bond formation in the promiscuous vole by inserting the vasopressin gene from the monogamous prairie vole into the promiscuous vole.
this vasopressin receptor gene too: For more on the vasopressin receptor gene in humans, see Aragona 2009, Adkins-Regan 2009, and Walum 2008.
to one woman for life: Walum 2008 found an association between one of the human vasopressin receptor genes and traits reflecting pair-bonding behavior in men. They showed that the vasopressin genotype of men also affects marital quality as perceived by their wives.
mating strategy for short-term partners: Haselton 2005.
to have sex with them: Haselton 2005.
and business and social connections: Reviewed in Shackelford 2005d and Buss 2005b.
and brain closer to Frank: For more on female brain, oxytocin, and pair bonding, see Liu 2003.
the more he squirmed: Loving 2009 found an increased stress reaction in men when discussing commitment or marriage.
electrical strain while they lied: O’Hair 1987.
couldn’t get enough of her: Gillath 2008a found that sex increases the desire to share personal information, fosters intimacy-related thoughts, and promotes a willingness to sacrifice for one’s partner. Klusmann 2002 found that although sexual activity and sexual satisfaction decline in women and men as the duration of the partnership increases, sexual desire declines only in women, not in men. (And the desire for tenderness declines in men and rises in women.) They conclude that a stable pair bonding does not require high levels of sexual desire for women, after an initial phase of infatuation has passed. But for men the opposite is true. They found that male sexual desire should stay at a high level because it
was selected for in evolutionary history as a precaution against the risk of sperm competition.
necessary part of getting there: For more on the male brain, pair-bond formation, and intercourse, see Liu 2001.
getting a primitive biological craving: For more on the specific brain areas where dopamine exerts its effects on pair bonding, pleasure, reward, and motivation, see Curtis 2006.
neurotransmitter for motivation and reward: Aragona 2009 found that dopamine transmission mediates the formation and maintenance of monogamous pair bonds. For more on motivation and reward in pair-bond formation, see Kruger 1998, Exton 2001a, and Young 2009.
anticipation of pleasure and reward: Knutson 2008 found that the nucleus accumbens (NAc) activation increases during anticipation of pleasure and deactivates during anticipation of loss in a relationship.
mixed with estrogen and oxytocin: Both males and females have oxytocin, vasopressin, testosterone, and estrogen, but the ratios are sex-specific and controlled by genes, proteins, and enzymes like aromatase. For more on the male brain, estrogen, and aromatase, see Wu 2009. For more on pair-bond formation in males and females, see Liu 2003, Bocklandt 2007, Becker 2008a, and Carter 2008.
head over heels in love: For more on the brain and intense romantic love, see Aron 2005 and Fisher 2005 and 2006.
their bodies and brains became: Gonzaga 2006.
moments daydreaming about their lovers: Fisher 2004.
they focused only on Nicole: Fisher 2006 found that when the in-love subjects looked at their beloveds, men also showed positive activity in a brain region associated with erection hardness. This means that the male love-response directly links romantic passion with a brain region associated with sexual arousal. Beauregard 2009 describes specific brain circuits for unconditional love.