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Women
Prefer Larger Penises Because They Are
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Sexual SelectionScientists believe that females chose males with larger, sexually stimulating organs above males with smaller genitals. The basic thing to understand is the concept of Sexual Selection, which is a special type of natural selection. There are two forms of sexual selection: intra-sexual selection and epigamic selection. Epigamic selection is the one that matters to us. It occurs when females accept males with certain characteristics over other males. An example is the human male's penis. With time female choice has caused it to develop to a "large" size, since females preferred mating with males possessing a large penis.
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Sexual Selection and Female Choice:"So, when a woman proceptively approaches this man and not that,
she has de facto made a selection. On the other hand, if the man approaches her, she also decides to accept or
reject. If, for whatever her reasons, she finds him "uninteresting" and turns away, she has selected him out. Or, if she responds positively to him, she has given him a chance to proceed.
Either way, she makes the choice." Female Choice and Penis Size:"We do not know why men have conspicuous genitals, but a male chimp solicits a female
by opening his legs, displaying an erect penis and flicking his phallus with a finger as he gazes at a potential partner. A
prominent, distinctive penis helps broadcast one's individuality and sexual vigor, which
may lure female friends. In many species of insects and primates, males have exceptionally elaborate penises, and scientists think these evolved specifically because
females chose those males with elaborate, sexually stimulating
genitals. So perhaps as Lucy's ancestors became bipedal some four million years ago, males began to parade their genitals in order to make special friends with favored females--selecting for those with large organs." Female Promiscuity:
"Roger Short...had predicted that in {primate} species where females mate with more than one male during a reproductive cycle, the
males would have larger testes for their body size than in species whose females had only a single mate per cycle. When the females were
promiscuous, the sperm of each male would have to compete with those of other males, and the male producing the most sperm was most likely to generate offspring. [quote from] (Harvey and Clutton-Brock 1983, p. 315" Female Choice and Penis Size:"One characteristic among primates has been clearly targeted for possible selection by Fisherian female choice--male penis size. Primate males living in groups with many females and many males, groups in which promiscuity is the mating rule, have long penes (Dixon 1978). Male chimps, in fact, use their penes for display toward estrous females. Because a longer penis would give a female pleasure (note that the human male has the longest and thickest penis of any primate),
female choice might have been a factor driving penis length to extremes among primates." Sperm Competition and Penis Size:
Sperm competition can occur even if a female copulates with different males several days apart. This is because sperm are hardy and may survive in the vagina of a chimpanzee or woman for as long as eight or nine days. Any female who copulates with more than a single male while ovulating opens the gates to a sperm race. (...)
Copious sperm production (estimated by testicle weight), deep penetration, and an elongated penis are all presumably
advantages to males engaged in sperm competition. Perhaps most important is sheer sexual vigor, with more active males ejaculating the greatest number of times gaining a competitive edge (...) There is also evidence that a
woman who climaxes while making love to her lover is more likely to become pregnant by him." Sperm Competition and Penis Size:
"An excessively large penis produced by epigamic selection would be no less effective in delivering sperm than one of optimal length, but a substantially
shorter (than optimal) penis would obviously place its owner's ejaculates at a disadvantage in competition with those deposited by a longer organ. Therefore it may be possible to test some predictions of the ejaculate delivery/sperm competition hypothesis for human penis length and distinguish this function from one of display." Female Promiscuity and Testicle Size:
"More convincing vestiges of a sexual selective history in which females mated polyandrously can be found in the human male. Perhaps the clearest such vestige is testis size (Short, 1977). Men's
testes are substantially larger, relative to body size, than those of gorillas, a species in which males are polygynous but females mate monogamously so that "sperm competition" within the female reproductive tract is absent. (goes on to talk of chimpanzees)" Female Promiscuity:
"Large testes and big penises are advantages only under conditions of widespread sexual promiscuity. Among our closest relatives the great apes, only male chimpanzees have testicles more prodigious than those of men. And chimps, with their big, heavy testicles, are more sexually promiscuous than humans. that the sperm-producing organs of chimps and humans are relatively big and heavy strongly suggests that some of our not-so-distant hominid ancestors were
far more promiscuous than gorillas and orangutans --- or than many people are today. In the evolutionary past, the competition to reach primate eggs was sometimes between sperm from different male donors. If two or more males copulated with the same female within a period of days, an advantage in begetting offspring accrued to the one who ejaculated the greatest quantity of vigorous sperm cells. (...) the
male with the best-timed copulation, most far-reaching
ejaculation, and biggest testicular "engine" able to produce the
greatest quantity of sperm
tended to win the "game" of
impregnation." Penis Size and Pregnancy:
"The large average size of the human penis (five to six inches, versus three for chimps, and one-half that for gorillas) may have been, evolutionists speculate, to frighten other males. Or to attract females. Or to enhance their pleasure. Perhaps the best hypothesis is that the
longer penis delivers sperm more closely to the eggs: today's biologists claim that for females who mated with several males, the male with the longest penis delivered his sperm more safely." Female Promiscuity and Testicle Size:
"As we have seen, chimpanzees live in groups where several males may share a female, and therefore there is a premium on the ability to ejaculate often and voluminously---he who does so has the best chance of being the father. This conjecture holds up across all the monkeys and across all rodents. The more they can be sure of sexual monopoly, as the gorilla can, the smaller their testes; the more they live in multimale promiscuous groups, the larger their testes. It began to look as if Short had stumbled on an anatomical clue to a species' mating system:
Big testicles equals polygamous females.
(...) Let us now apply this prediction to man. For an ape, man's testicles are medium-sized---considerably bigger than a gorilla's. Like a chimpanzee's, human testicles are housed in a scrotum that hangs outside the body where it keeps the sperm that have already been produced cool, therefore increasing their shelf life, as it were. This is all
evidence of sperm competition in man. But human testicles are not nearly as large as those of chimps, and there is some tentative evidence that they are not operating on full power (that is, they might once have been bigger in our ancestors): Sperm production per gram of tissue is unusually low in man. All in all, it
seems fair to conclude that women are not highly
promiscuous, which is what we expected to find." Sexual Selection and Clitoris Size:
"Based on this analysis of the adaptive functions of female orgasm, we can start to understand why the female
clitoris remained small and relatively hard to stimulate, while the male penis enlarged to unprecedented proportions in our linage. Maintenance of a small, relatively hidden, and relatively hard-to-stimulate clitoris
enhanced female discernment and choosiness with respect to assessing sexual stimulation by
males. A larger, more protuberant clitoris which could have been effectively stimulated by almost any tactile contact, however inept, would have made its female bearer less able to judge the relative stimulation capabilities of different males. She might have mated with less sexually competent males and produced less sexually competent sons." Penis Size and Genetics:
"... Applied to sexual selection, this means that sons will tend to inherit their mother's mate preferences, and daughters will tend to inherit their father's sexually-selected traits. To cite an example from Dawkins (1986),
one is as likely to inherit the genes for a large penis from one's mother as from one's
father." Importance of Sexual Selection:
"The massive space devoted to hands, lips, tongue, and genitals in the primary sensory and motor cortices of the human brain can be interpreted as reflecting their
sexual-selective importance in courtship, foreplay, and copulation, as much as their ecological significance." |
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