Penis: Größe, Umfang und sexuelle Selektion

Der Penis ist bekanntermaßen der Mercedes unter den Geschlechtsorganen,  um so verwunderlicher, dass er in einem patriarchischen Blog wie diesem bisher zu …äh… kurz kam.

Gerade behandelt eine aktuelle Studie die Frage, wie Penisgröße und Attraktivität zusammenhängen:

Compelling evidence from many animal taxa indicates that male genitalia are often under postcopulatory sexual selection for characteristics that increase a male’s relative fertilization success. There could, however, also be direct precopulatory female mate choice based on male genital traits. Before clothing, the nonretractable human penis would have been conspicuous to potential mates. This observation has generated suggestions that human penis size partly evolved because of female choice. Here we show, based upon female assessment of digitally projected life-size, computer-generated images, that penis size interacts with body shape and height to determine male sexual attractiveness. Positive linear selection was detected for penis size, but the marginal increase in attractiveness eventually declined with greater penis size (i.e., quadratic selection). Penis size had a stronger effect on attractiveness in taller men than in shorter men. There was a similar increase in the positive effect of penis size on attractiveness with a more masculine body shape (i.e., greater shoulder-to-hip ratio). Surprisingly, larger penis size and greater height had almost equivalent positive effects on male attractiveness. Our results support the hypothesis that female mate choice could have driven the evolution of larger penises in humans. More broadly, our results show that precopulatory sexual selection can play a role in the evolution of genital traits.

Quelle: Penis size interacts with body shape and height to influence male attractiveness

Also ein gewisser Zusammenhang zwischen Penisgröße und Attraktivität, allerdings insbesondere im Rahmen eines Gesamtpakets. Um so besser der Rest des Körpers, um so mehr wirkt auch ein großer Penis.  Allerdings wurde er hier auch im schlaffen Zustand betrachtet

Discussion We found that flaccid penis size had a significant influence on male attractiveness. Males with a larger penis were rated as being relatively more attractive. This relationship is nonlinear, however, indicating that the proportional increase in attractiveness begins to decrease after a size of∼7.6 cm (Fig. 2), which is an under-average penis size based on a large-scale survey of Italian men (39). Although we detected quadratic selection on penis size, any potential peak (i.e., the most attractive penis size) appears to fall outside the range used in our study. A preference for a larger-than-average penis is qualitatively consistent with some previous studies (30–32), but our results differ in showing that the most attractive size appears to lie more than 2 SDs from the mean (i.e., no evidence for stabilizing sexual selection, in contrast to refs. 30–32). Our results are further supported by the analysis of response time. We found a significantly positive, albeit small, correlation between penis size and response time. This finding is consistent with a pattern in adults whereby attractive stimuli are viewed for a longer periods (40). A tendency to view attractive stimuli for longer is a generalized phenomenon that starts in infancy (41, 42). (…) The effect of penis size on attractiveness varied with both height and body shape (Fig. 3B). After controlling for the shoulder-to-hip ratio, larger penis size had a greater effect on attractiveness for taller men. This result could be because perceived penis size was smaller when assessed relative to the height of a taller man; or because of general discrimination against short men irrespective of the value of other traits, so that even a larger penis did little to increase their net attractiveness. A similar relationship between penis size and shoulder-to-hip ratio was also detected (Fig. 3A).

Wäre interessant, wie es bei steifen Penis aussieht. Allerdings geht es ja hier auch nur um Attraktivität, was ja in diesem Bereich nicht alles ist.

The media equate a man’s penis size with his power and masculinity. Views about penis size were assessed in an Internet survey of 52,031 heterosexual men and women. Most men (66%) rated their penis as average, 22% as large, and 12% as small. Self-reported penis size was correlated positively with height and negatively with body fat level. Whereas 85% of women were satisfied with their partner’s penis size, only 55% of men were satisfied with their penis size, 45% wanted to be larger, and 0.2% wanted to be smaller. Satisfaction did not vary across age groups from 18 to 65. Men reporting a larger-than-average penis rated their appearance most favorably, suggesting a possible confidence effect of perceived large penis size.

Quelle: Does Size Matter? Men’s and Women’s Views on Penis Size Across the Lifespan

Da sind auch erst einmal konkrete Daten zur Penisgröße genannt:

Combining the means and standard deviations reported by these researchers, we calculated that the mean erect penis length was 5.3 in. (13.5 cm), with 68% of men measuring between 4.6 and 6.0 in. (11.7 cm and 15.2 cm), 13.5% between 3.8 and 4.5 in. (9.7 cm and 11.4 cm), and 13.5% between 6.1 and 6.8 in. (15.5 cm and 17.3 cm); only about 2.5% of men possessed a penis over 6.9 in. (17.5 cm) long, and 2.5% were under 3.7 in. (9.4 cm) long.

Mit einem Penis von 13,5 cm ist man also im guten Durchschnitt, it 17,5 cm schon im deutlich oberen Bereich.

Interessant auch Geoffrey Miller über die Entwicklung des Penis durch sexuelle Selektion in „The Mating Mind„:

Continuous sexual receptivity and concealed ovulation gave our female ancestors an unprecedented opportunity for testing males as sexual partners, while running a lower risk per copulation of unwanted pregnancy than any other primate did. Sex during menstruation, pregnancy, and breast-feeding would also have given ample opportunity for judging potential long-term lovers by their copulatory skills. In species that do not use copulatory thrusting, especially insects, penises evolve more obvious tactile stimulators: nubs, spikes, ridges, curls, barbs, hooks, and flagella. Male insects often try to push each other off during copulation, so copulatory thrusting would risk disengagement. Better to lock the genitals together and have internal flagella to excite the female. With primates, it is not so common for male rivals to swarm over females knocking each other off. This allows couples a bit more copulatory leisure, with more complex movements favoring simpler penis designs. The human penis is especially streamlined because ancestral females apparently favored whole-body copulatory movement over the flagellar vibrations favored by female insects. Perhaps whole-body copulatory movements, requiring much more energy than waving a couple of vibrators on the end of the glans, were better indicators of physical fitness. It is not clear whether many middle-aged men do actually have heart attacks during vigorous sex with mistresses, but this plausible risk reveals the energetic costs of human copulation, and one way that female demands for tactile stimulation separate the healthy from the unhealthy. The loss of the baculum (penis bone) also reveals female choice for tactile stimulation. Since male human penises become erect with blood rather than muscle and bone, this gives them more flexibility, and permits a greater range of copulatory positions. Although bonobos also enjoy face-to-face copulation, their positional variety pales in comparison to the Kama sutra.

Human penises evolved as tactile stimulators for use in copulatory courtship. Further research may clarify whether penises and copulatory courtship evolved mostly as fitness indicators or just as sexually selected entertainment. Female hominids may not have preferred thicker, longer, more flexible penises per se. They may simply have liked orgasms, and larger penises led to better orgasms by permitting more varied, exciting, and intimate copulatory positions. This rather contradicts the view of the penis as a symbol of male domination. If we were a species in which males dominated the sexual system, we would have one-inch penises like dominant gorillas. The large male penis is a product of female choice in evolution. If it were not, males would never have bothered to evolve such a large, floppy, blood-hungry organ. Ancestral females made males evolve such penises because they liked them.

Hier wird der Penis seiner Unterdrückungsfunktion beraubt und als Ergebnis der weiblichen Wahl dargestellt. Weibliche Wahl hätte demnach den Penis in seine heutige Form gebracht.

Und hier eine weitere Studie:

Abstract OBJECTIVE: A great deal of men consider that the size of the penis is directly proportional to its sexual power. Some men, who are worried that their penis is too small, wish to be considered for surgical lengthening or thickening procedures. The argumentation for this chiefly points in the direction of women. However, have women actually been asked about the extent to which they consider the size of the penis to be of importance from a sexual point of view? Or asked what they think about ideas surrounding the size of the penis in relation with actual sexual functioning?

PATIENTS AND METHODS: To address these questions, 375 sexually active women who had recently given birth at the University Hospital Groningen were asked a number of questions about sexual functioning and the importance they attach to the size of their partner’s penis.

RESULTS: A total of 170 questionnaires were returned (response rate 45%); 20% of the women found the length of the penis important and 1% very important; 55% and 22% of the women found the length of the penis unimportant and totally unimportant, respectively. Opinions about the girth of the penis followed the same trend. Length was less important than girth: 21% and 32%, respectively. The women who found the girth of the penis important had the same opinion about the length of the penis (correlation 0.71, p=-0.001). Median division into two subgroups (girth important/unimportant; t-test) did not reveal any significant differences in relation with demographic data. Correlation analysis did not reveal any significant correlation between sexual functioning (measured with the NSF) and opinions about the girth of the penis.

CONCLUSION: Although clearly in the minority, a nevertheless considerable percentage of the women respondents attached substantial importance to the size of the male sexual organ.

Quelle: What importance do women attribute to the size of the penis?

Demnach kommt es eher auf den Umfang an als auf die Länge.

Eine weitere Studie betont ebenfalls die Bedeutung des Umfangs:

Background

Does the size of the male penis, in terms of length or width, make a difference in female sexual satisfaction?

Method

To study the effect of penis width vs. length on female sexual satisfaction, 50 sexually active female undergraduate students were asked which felt better, i. e., was penis width or length more important for their sexual satisfaction.

Results

None reported they did not know, or that width and length were equally satisfying. A large majority, 45 of 50, reported width was more important (p < .001).

Conclusion

Implications are discussed, including the fact that the data seem to contradict Masters and Johnson about penis size having no physiological effect on female sexual satisfaction.

Quelle: Penis size: Survey of female perceptions of sexual satisfaction

Auch hier also ein deutlicher Sieg für den Umfang. Allerdings dürfte es auch hier so sein, dass ganz kleine Längen das eigentlich Problem darstellen, und es erst danach auf die weiteren Umstände ankommt.