Sex Differences in Libido

Inspired by previous thread asking if women underestimate male sexuality. To which I would say yes to some degree, given the accounts of FtM transgender people experiencing explosions in sex drive. Anyway, here are some references for sex differences in libido which seem to support the idea that men's sex drives are a fair bit higher than women's, an idea which I see occasionally disputed here.

Gender differences in behaviour: activating effects of cross-sex hormones.

The relative contribution of organizing and activating effects of sex hormones to the establishment of gender differences in behaviour is still unclear. In a group of 35 female-to-male transsexuals and a group of 15 male-to-female transsexuals a large battery of tests on aggression, sexual motivation and cognitive functioning was administered twice: shortly before and three months after the start of cross-sex hormone treatment. The administration of androgens to females was clearly associated with an increase in aggression proneness, sexual arousability and spatial ability performance. In contrast, it had a deteriorating effect on verbal fluency tasks. The effects of cross-sex hormones were just as pronounced in the male-to-female group upon androgen deprivation: anger and aggression proneness, sexual arousability and spatial ability decreased, whereas verbal fluency improved. This study offers evidence that cross-sex hormones directly and quickly affect gender specific behaviours. If sex-specific organising effects of sex hormones do exist in the human, they do not prevent these effects of androgen administration to females and androgen deprivation of males to become manifest.

Is There a Gender Difference in Strength of Sex Drive? Theoretical Views, Conceptual Distinctions, and a Review of Relevant Evidence (this is a meta-analysis)

The sex drive refers to the strength of sexual motivation. Across many different studies and measures, men have been shown to have more frequent and more intense sexual desires than women, as reflected in spontaneous thoughts about sex, frequency and variety of sexual fantasies, desired frequency of intercourse, desired number of partners, masturbation, liking for various sexual practices, willingness to forego sex, initiating versus refusing sex, making sacrifices for sex, and other measures. No contrary findings (indicating stronger sexual motivation among women) were found. Hence we conclude that the male sex drive is stronger than the female sex drive. The gender difference in sex drive should not be generalized to other constructs such as sexual or orgasmic capacity, enjoyment of sex, or extrinsically motivated sex.

Sex Differences in Succumbing to Sexual Temptations

Men succumb to sexual temptations (e.g., infidelity, mate poaching) more than women. Explanations for this effect vary; some researchers propose that men and women differ in sexual impulse strength, whereas others posit a difference in sexual self-control. These studies are the first to test such underlying mechanisms. In Study 1, participants reported on their impulses and intentional control exertion when they encountered a real-life tempting but forbidden potential partner. Study 2 required participants to perform a reaction-time task in which they accepted/rejected potential partners, and we used process dissociation to separate the effects of impulse and control. In both studies, men succumbed to the sexual temptations more than women, and this sex difference emerged because men experienced stronger impulses, not because they exerted less intentional control. Implications for the integration of evolutionary and self-regulatory perspectives on sex differences are discussed.

Human Sexuality How Do Men and Women Differ?

A large body of scientific research documents four important gender differences in sexuality. First, on a wide variety of measures, men show greater sexual desire than do women. Second, compared with men, women place greater emphasis on committed relationships as a context for sexuality. Third, aggression is more strongly linked to sexuality for men than for women. Fourth, women's sexuality tends to be more malleable and capable of change over time. These male-female differences are pervasive, affecting thoughts and feelings as well as behavior, and they characterize not only heterosexuals but lesbians and gay men as well. Implications of these patterns are considered.

This one has to do with response to visual sexual stimuli: Men and women differ in amygdala response to visual sexual stimuli

Men are generally more interested in and responsive to visual sexually arousing stimuli than are women. Here we used functional magnetic resonance imaging (fMRI) to show that the amygdala and hypothalamus are more strongly activated in men than in women when viewing identical sexual stimuli. This was true even when women reported greater arousal. Sex differences were specific to the sexual nature of the stimuli, were restricted primarily to limbic regions, and were larger in the left amygdala than the right amygdala. Men and women showed similar activation patterns across multiple brain regions, including ventral striatal regions involved in reward. Our findings indicate that the amygdala mediates sex differences in responsiveness to appetitive and biologically salient stimuli; the human amygdala may also mediate the reportedly greater role of visual stimuli in male sexual behavior, paralleling prior animal findings.

Gender differences in sexuality: a meta-analysis.PDF here

This meta-analysis surveyed 177 usable sources that reported data on gender differences on 21 different measures of sexual attitudes and behaviors. The largest gender difference was in incidence of masturbation: Men had the greater incidence (d = .96). There was also a large gender difference in attitudes toward casual sex: Males had considerably more permissive attitudes (d = .81). There were no gender differences in attitudes toward homosexuality or in sexual satisfaction. Most other gender differences were in the small-to-moderate range. Gender differences narrowed from the 1960s to the 1980s for many variables. Chodorow's neoanalytic theory, sociobiology, social learning theory, social role theory, and script theory are discussed in relation to these findings.

SEX DIFFERENCES AND SIMILARITIES IN FREQUENCY AND INTENSITY OF SEXUAL DESIRE

Only within the past decade have social scientists commonly recognized the phenomenon of sexual desire as a distinct and vital component of human sexual response. Of the various factors believed to be associated with sexual desire, gender (biological sex) is presumed by many theorists to be one of the most important. Limited empirical work suggests that men experience desire more frequently than do women; however, sex differences in intensity or level of desire have yet to be examined. This study explored both the self-reported frequency and intensity of sexual desire among an ethnically diverse sample of 676 men and women. As hypothesized, men reported experiencing a higher overall level of sexual desire than did women. Sex differences also were found with respect to frequency of sexual desire. Men reported experiencing sexual desire more often than did women and, when asked to estimate the actual frequency with which they experienced desire, men's estimated frequency (37 times per week) was significantly higher than women's (9 times per week). These results do not imply that men always feel desire or that women lack sexual desire. In fact, virtually every participant in this study reported feeling sexual desire on a regular basis. This suggests that desire may be the most universal sexual response experienced by both men and women.

The experience of sexual desire: Psychological correlates in a college sample

In order to elaborate on available models of sexual desire, we administered a sexual desire questionnaire to 144 college students, ages 18 to 54. Included in this measure were questions concerning the frequency of sexual desire, whether the respondent had participated in sexual activity without desire, or vice versa, experienced desire without sexual behavior, and a question assessing which cues are used by the subject to gauge sexual desire (e.g., frequency of intercourse, sexual dreams). Subjects also completed the Passionate Love Scale, Sexual Arousal Inventory, and Crowne‐Marlowe Social Desirability Scale. The results indicate that as a group, males report experiencing sexual desire more frequently than females. Males appeared to rely on similar indicators of desire as females, specifically genital arousal and sexual daydreams. For both males and females, sexual desire was significantly correlated with sexual arousal (r = 0.50, females; r = 0.44, males) while the correlation of desire and love was nonsignificant for both sexes. However, desire and sexual behavior did not necessarily co‐occur, as both males and females reported engaging in sexual behavior without desire. These data suggest that greater attention be paid to the definitional features of sexual desire in nonclinical samples, in an effort to clarify current diagnostic categories and to provide population base rates.

Sexual interest and behavior in healthy 80- to 102-year-olds. (lol)

Sexual interest and behavior of 100 white men and 102 white women ranging in age from 80-102 were studied using an anonymous 117-item questionnaire. Subjects were healthy and upper middle-class, and living in residential retirement facilities; 14% of the women and 29% of the men were presently married. For both men and women, the most common activity was touching and caressing without sexual intercourse, followed by masturbation, followed by sexual intercourse. Of these activities, only touching and caressing showed a significant decline from the 80s to the 90s, with further analyses revealing a significant decline in this activity for men but not for women. Except for past enjoyment of sexual intercourse and of touching and caressing without sexual intercourse, all analyses revealed sex differences reflecting more activity and enjoyment by men. Current income and past guilt over sexual feelings showed very low but significant correlations with some frequency and enjoyment measures, and marital status, extramarital sex, and church attendance were significantly associated with continuing to perform and enjoy some sexual behaviors. Past importance of sex was significantly correlated with present frequency and enjoyment of both sexual intercourse and touching and caressing without sexual intercourse. Correlations between past and present frequency of sexual behaviors were substantial and significant for all but frequency of sexual intercourse, suggesting that current physical and social factors play an overriding role in this area.

Here is a summary of a paper on the interaction of testosterone and social status, which is only tangentially related, but presumably of interest to many readers here. A taste of the summary:

individuals who generally have higher scores on self-reported dominance and higher basal levels of testosterone show vigilant responses to angry facial expressions (reviewed in [42]). Furthermore, exogenous administration of testosterone increases the sympathetic heart-rate response to angry, but not to happy facial expressions [43] (Figure 2). Although this could theoretically also reflect autonomic arousal as part of a fear response, testosterone has been shown to reduce fear [44], suggesting that dominant people perceive an angry face as a challenge….a recent testosterone administration study has shown that facial mimicry [“a precursor of empathy-related processes occurring automatically”] in response to emotional facial expressions is relatively suppressed after a single dose of testosterone [48]…a single administration of testosterone to young females leads to a significant impairment in the ability to infer emotions, intentions and feelings from the eye region of the face [49]. In addition, the same study established that subjects’ second-to-fourth digit ratio, which is thought to be a marker of prenatal testosterone exposure, is largely able to predict this effect…In line with this are findings of decreased trustworthiness ratings of facial photographs in subjects who received a single dose of testosterone [51]. Crucially, this effect was driven most strongly by those who trusted easily, suggesting that testosterone adaptively increases social vigilance in these trusting individuals to better prepare them for competition over status and valued resources

In contrast to the controversial role of testosterone in aggression, a mounting body of evidence in both animals and humans suggests that testosterone drives a more general repertoire of motivated behaviors, often subsumed under the concept of dominance behavior [1]. Dominance behavior refers to the motivation of an individual to achieve or maintain a high social status, which appears to be achieved non-aggressively in primates [15]. Thus, testosterone seems to influence an underlying motive rather than aggression per se. For instance, rhesus monkeys with high testosterone levels use stares, threats and displacements, rather than overtly aggressive interactions, to ascertain high social status [16]. In humans, status might be asserted in similarly subtle ways; for example, in faceto-face interactions by increased staring duration, speech duration and body postures displaying supremacy [15] (Figure 1). Nevertheless, physical violence might still be a component of status-seeking behavior in certain contexts [17] and it has been emphasized that one must control for whether the aggression displayed is suitable for improving the social status of a subject [18]. It is possible that this might ultimately reveal a more consistent positive relationship between adaptive aggressiveness in the context of status seeking and testosterone (Figure 1).

TLDR: Men on average experience greater frequency and intensity of sexual desire than women. This appears to be related in large part to testosterone level differences. On average, men also masturbate much more often, want more frequent sexual intercourse, are less likely to be willing to forego sex, and are willing to make more sacrifices in order to get sex. The male impulse for sex appears to be stronger than the female impulse for sex, and males are less likely to care about being in a committed relationship in the context of sex/sexual desire.

Edit: I bolded the most salient pieces so those who don't want to read the admittedly large amount of text can get the main points.