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Chapter 6

CHAPTER 6 NOTES - Evolutionary Psych

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Department
Psychology
Course
PSYC 3420
Professor
Irwin Silverman
Semester
Fall

Description
CHAPTER 6: Short-term Sexual Strategies THEORIES OF MEN’S SHORT-TERM MATING Adaptive Benefits for Men of Short-Term Mating • Theory of parental investment and sexual selection: men, more than women, are predicted to have evolved a greater desire for casual sex • The same act of sex that causes a woman to invest nine months of gestation obligates the man to practically no investment • The reproductive benefits for men who successfully pursued a short-term mating strategy would have been direct: an increase in the number of offspring produced • Historically, men appear to have achieved increase in reproductive success mainly through increases in the number of sexual partners, not through increases in the number of children per partner Potential Costs of Short-Term Mating for Men • Short-term sexual strategies carry potential costs for men. Over time men risked: 1) Contracting sexually transmitted diseases 2) Getting a social reputation as a “womanizer” which could impair their chances of finding a long- term mate 3) Lowering the chances that their children would survive owing to lack of paternal investment and protection 4) Suffering violence at the hands of jealous husbands or boyfriends if they women were married or mated 5) Suffering violence at the hands of the brother/father of the women 6) Risking affairs and the potential for a costly divorce • Given the large potential adaptive advantages of short-term mating for men in the currency of increase offspring production, selection might have favoured a short-term mating strategy despite these costs BOX 6.1 FUNCTIONS vs. BENEFICIAL EFFECTS OF SHORT-TERM MATING Adaptive Problems Men Must Solve When Pursuing Short-Term Mating • Ancestral men who pursued a short-term sexual strategy confronted a number of specific adaptive problems-partner number or variety, sexual accessibility, identifying which women were fertile, and avoiding commitment The Problem of Partner Number or Variety Advantages of short term mating 1) Desire for sexual access to a large number of women 2) A relaxation of standards that men might impose for an acceptable short-term partner 3) Impose minimum time constraints-to let little time elapse before seeking sexual intercourse The Problem of Sexual Accessibility • Specialized adaptations for solving the problem of sexual accessibility might occur in the form of men’s short-term mate preferences • Women who show signs of being prudish, sexually inexperienced, or low in sex drives should be disfavored • Clothes signaling sexual openness or behaviour signaling promiscuity might be desired by men in short-term mates because they suggest sexual accessibility The Problem of Identifying Which Women are Fertile • A clear evolutionary prediction is that men seeking short-term mates would prefer women who displayed cues correlated with fertility • A maximally fertile woman would have the highest probability of getting pregnant from a single act of sex • In contrast, men seeking long-term mates might be predicted to prefer younger women of higher reproductive value, because they will be more likely to reproduce in the future The Problem of Avoiding Commitment • The larger the investment in a particular women, the fewer the number of sexual partners a given man can succeed in attracting • Therefore, men seeking short-term mates are predicted to shun those who demand commitments before agreeing to sex EVIDENCE FOR AN EVOLVED SHORT-TERM MATING PSYCHOLOGY • Casual sex typically requires the consent of both sexes • At least some ancestral women must have practiced the behaviour some of the time Physiological Evidence for Short-Term Mating • Existing adaptations in our psychology, anatomy, physiology, and behaviour reflect the scoring of prior selection pressures 1) Testicle Size • Large testes typically evolve as a consequence of intense sperm completion-when the sperm from two or more males occupy the reproductive tract of one female at the same time because she has copulated with two or more males • Sperm competition exerts a selection pressure on males to produce large ejaculates containing numerous sperm • Men’s testes size, relative to their body weight, is far greater than that of gorillas and orangutans • Men’s relatively large testes provide one piece of evidence that women in human evolutionary history sometimes had sex with more than one man within a time span of a few days • This size of testes would have been unlikely to have evolved unless there was a sperm competition • Thus, the behaviour that leads to sperm competition-females having sex with a variety of males- appears to accord well with the evidence on sperm volume • Humans show higher level of sperm competition than the monogamous gorillas but far lower levels of sperm competition than the more promiscuous chimps and bonobos 2) Variations in sperm insemination • Another clue to the evolutionary existence of casual mating comes from variations in sperm production and insemination • Men’s sperm count went up dramatically with the increasing amount of time the couple had been apart since their last sexual encounter • The number of sperm inseminated increase when other men’s sperm might be inside the wife’s reproductive tract at the same time as a consequence of the opportunity provided for extramarital sex by the couple’s separation • The increase in sperm insemination upon being united id not depend on the time since the man’s last ejaculation • The increase in sperm inseminated by the husband after prolonged separation ensures that his sperm will stand a greater chance in the race to the egg by crowding out or displacing a possible interloper’s sperm Psychological evidence for Short-Term Mating 1) Desire for a variety of sex partners • One psychological solution to the problem of securing sexual access to a variety of partners is lust • Men have evolved a powerful desire for sex • Men do not always act on this desire, but it is a motivating force • In every culture in every region of the world, a substantially larger percentage of men than women desire more than one sex partner over the next month • Some psychologists argue that increased gender equality should result in a reduction or elimination of sex differences • In another study where people had to write down their “private wishes”, the largest sex difference by far was found for one wish “to have sex with anyone I choose • Men expressed a substantially greater desire than did women for a variety of sex partners 2) Time Elapsed Before Seeking Intercourse • Another psychological solution to the problem of gaining sexual access to a variety of partners is to let little time elapse between meeting the desired female and seeking sexual intercourse • Having known a potential mate for about a week, men are still on average positive about the possibility of consenting to sex • Women are highly unlikely to have sex after knowing someone for just a week • Men’s inclination to let little time elapse before seeking sexual intercourse offers a partial solution to the adaptive problem of gaining sexual access to a variety of partners • Men lower their standards for casual sex • Targets who displayed cues to “easy sexual access” were judged to be far more desirable by men than by women but only in the context of short-term mating 3) The Lowering of Standards in Short-Term Mating • Another psychological solution to securing a variety of casual sex partners is a relaxation of standards imposed by men for acceptable partners • High standards for attributes such as age, intelligence, personality, and marital status function to exclude the majority of potential mates from consideration • The relaxation of age restrictions by men does not apply to committed mating • Men also express significantly lower standards than the women on 42/667 characteristics named as potentially desirable in a casual mate • Men thus relax their standards across a range of attributes, which helps to solve the problem of gaining access to a variety of sex partners 4) Mate Preferences • The relaxation of standards does not mean that men have no standards • The standards that men set for sexual affairs reveal a precise strategy to gain sexual access to a variety of partners • Compared with their long-term preferences, for casual sex, men disliked women who are prudish, conservative, or have a slow sex drive • Promiscuity, high sex drive, and sexual experience in a woman probably signal an increased likelihood that a man can gain sexual access for the short-run • They also hypothesize that men seeking short-term sex would prioritize women’s bodies, since a woman’s body provides the most powerful cues to her fertility • Compared to the long-term mating context in which men prioritized facial information (in a study), men considering casual sex shifted significantly in the direction of prioritizing body information Women in contrast, do not show this shift, and tend to prioritize a man’s face in both short-term and long-term mating contexts These findings are consistent with the hypothesis that men prioritize cues to fertility in short-term sex partners 5) Minimizing Commitment after Sex • Men with more sex partners experienced a sharp decline in how sexually attractive they found their partner immediately following intercourse, whereas neither women no men with less sexual experience showed this decline • This work on the attraction-reduction effect supports the hypothesis that men have yet another psychological adaptation designed to propose the success of a casual sexual strategy,, ,one that motivates either a hasty postcopulatory departure to minimize investment in any one woman, or, alternatively, a roving eye within the context of an existing long-term mate ship 6) The Closing Time Phenomenon • A related psychological clue to men’s strategy of casual sex comes from studies that examine shifts in judgments of attractiveness over the course of an evening at singles bars • As closing time approached, men viewed women as increasingly attractive • Women’s judgments of men’s attractiveness also increased over time, but women perceived the male bar patrons as less attractive overall compared with the men’s perception of the women • This shift in men’s perceptions of attractiveness occurs regardless of how much alcohol they have consumed • As the evening progresses and a man has not yet been successful in picking up a woman, he views the remaining women in the bar as increasingly attractive • The closing time phenomenon appears to represent a psychological solution to the problem of sexual accessibility-a context-specific lowering of standards as the likelihood of sexual accessibility starts to drop 7) Sex Differences in Sexual Fantasies and Sex Drive • Sexual fantasies provide another psychological clue to an evolutionary history of men’s proclivity to casual mating • Fantasies reveal the nature of desires that motivate men’s and women’s behavior’s • When asleep, men are more likely than women to dream about sexual events • Men’s sexual fantasies more often include strangers, multiple partners, or anonymous partners • Men are also more than 4 times likely as women to have fantasies about group sex • Women’s sexual fantasies often contain familiar partners • They typically focus on someone with whom they are already romantically and sexually involved • Women tend to emphasize tenderness, romance, and personal involvement in their sexual fantasies • In every nation, men reported having a higher sex drive than did women • Similar findings also show up in masturbation rates and pornography consumption The sex difference in ex drive proved just as large in nations with high levels of gender quality as it did in nations with lower levels of gender equality- a finding that contradicts the notion that these sex differences are caused by this social-structural variable 8) Sexual Regret • Feelings of sorrow about something in the past- is hypothesized to function to improve future decision making by motivating people to avoid prior mistakes • Sexual regret could be missed sexual opportunities or sexual actions taken • Men more than women regret missed sexual opportunities • Women were more likely to have regretted having sex with someone than not having sex • A total of 46% in another study had two regrets: 1) That the women they hooked up with wanted a relationship 2) Overconsumption of alcohol or drugs o Sexual regret, has the hallmarks of an evolved feature in men designed to facilitate acting on future sexual opportunities and avoid entangling commitments Behavioural Evidence of Short-Term Mating • In this section, we complete the picture by presenting behavioural evidence that men across cultures actually pursue short-term mating more than women do 1) Extramarital Affairs • Men in most cultures pursue extramarital sex more often than do their wives • There seems to be no question but that the human male would be promiscuous in his choice of sexual partners throughout the whole of his life if there were no sexual restrictions • The human female is much less interested in a variety of partners 2) Prostitution • Men are overwhelmingly the consumers of prostitution across the globe • The numbers for women were so low that they were not even reported as a percentage of the sexual outlet of women 3) Hook-up Behaviour and Friends with Benefits • More men than women try to initiate hooking up and are more likely than women to report having at least one friend with benefits • Men more than women report that their ideal outcome of hooking up is “Further hookups” • Women said their “ideal outcome” would be a “traditional romantic relationship” • Women may perceive it as the early stage of a romantic relationship • Women also report feelings of more regret being used, and depression following hook-ups and one- night stands WOMEN’S SHORT-TERM MATING Evidence for Women’s Short-Term Mating • Mathematically, the number of short-term mating must be identical, on average, for men and women • If ancestral women never engaged in short-term mating, en could not have evolved a powerful desire for sexual variety • If ancestral women willingly engaged in short-term mating, it would defy evolutionary logic if there were no benefits to women of doing so 1) Orgasm in Women • The physiology of women’s orgasm provides one clue to an evolutionary history of short-term mating • Once it was though that a woman’s orgasm functioned to make her sleepy, thereby decreasing the likelihood that sperm would flow out and increasing the likelihood that she would conceive • That is not the case, there is no link between the timing of the flow back and the number of sperm retained • Women discharged roughly 35% of sperm within 30 minutes of the time of insemination, averaged across all instances of intercourse • If she has an orgasm, this retains 70 percent of the sperm, ejecting only 30 percent • This 5% difference isn’t large, but if it occurred repeatedly, in woman after woman, generation after generation, it could add up to a large selection pressure over evolutionary time • Lack of an orgasm leads to the ejection of more sperm • This evidence is consistent with the theory that a woman’s orgasm functions to draw the sperm from the vagina in to the cervical canal and uterus, increasing the probability of conception • The number of sperm a woman retains is also linked with whether she is having an affair • Women that have affairs, most likely unconsciously coincide with the point in their menstrual cycle when they were most likely to conceive • Women who are having affairs are more likely to be orgasmic with the affair partners than with their regular partner 2) Behavioural Evidence • The behavioural evidence also suggests that women in all but the most restrictive societies sometimes engage in extramarital sexual unions • Studies of college women reveal that they do have sex with their opposite sex friends, as well as attempting to initiate hookups • Modern cultural and tribal behavioural evidence, in short, does not suggest that woman invariably pursue a monogamous long-term mating strategy all of the time Hypotheses about the Adaptive Benefits to Women of Short-Term Mating • For short-term sexual psychology to evolve in women, there must have been adaptive benefits associated with casual sex in some circumstances 1) Resource Hypotheses i. Investment via paternity confusion o According to the paternity confusion hypothesis, each man might be willing to offer some investment in the woman’s children on the chance that they are genetically his own o An ancestral woman might have been able to obscure the actual paternity of her of her offspring through several short-term mating and thus elicit resources from two or more men ii. Immediate economic resources o Women would engage in short-term mating in exchange for meat, goods, or services iii. Protection through “special friendships” o Men typically provide protection to their mates and children, including defense against predators and aggressive men o Because a primary mate cannot always be around to defend and protect a woman, she might gain added protection with another man iv. Status elevation o “status enhancement hypothesis” a woman might be able to elevate her social standing among her peers or gain access to a higher social circle by a temporary liaison with a high-status man 2) Genetic Benefit Hypotheses i. Better or “sexy son” genes o A short-term mate might provide “superior genes” compared with a woman’s regular mate, especially if she has an affair with a healthy or high status man o These genes might give her offspring better chances for survival or reproduction o “sexy son hypothesis” by mating with an especially attractive man, a woman might be able to bear a son who is especially attractive to women in the next generation o Her son might have increased sexual access, produce more children, and provide his mother with additional grandchildren ii. Diverse genes o A short-term mate might provide a woman with different genes compared with those of her regular mate, thus enhancing the genetic diversity of her children-perhaps a hedge against environmental change iii. Enhanced fertility o If a woman’s regular mate is infertile a short=term mate might provide a fertility backup to aid in conception 3) Mate Switching Hypotheses
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