Size and Natural Selection

[vibratingfinger]

WOW, if women were so concerned with conception they would all marry fertility specialists. It would have to be a polygamous affair as well since there is a shortage.

 

[Wyldgusechaz]

Penis size is likley one the smallest determinant in mating. To use a pun, its not that big a deal.

Women"s eyes (and men"s too) are far more likely to be drawn to mates who have certain traits that define attractiveness.

IMO a man demonstrating perfectly symmetrical lines with broader shoulders, taller than average, narrower waist, clear skin and eyes, nice muscular ass, vivd coloring, a nicely muscular build, and intelligence will beat a less attractive man with a huge dick. For about 99% of the ladies out there. Throw in a big cock as dessert and there you have it, perfection but the cock is last.

Females instinctively want to reproduce with the man whose genes are more likely to produce stronger, better built offspring. And men the same.

 

[earllogjam]

Just a thought - a big penis is a drawback in colder climates where you need to worry about frostbite.

 

[B_spiker067]

Well, it isn't quite that simple!

Again, not quite that simple.
As other members have pointed out, man already has the largest penis of any primate. Why is this? Any student of recent cultural history, this site being an excellent example, would have noticed a paradigm shift in the way that the penis is being discussed openly amongst both sexes. There is even a gender difference emerging, whereas men have traditionally thought in terms of length as the salient trait when describing the concept of penile size, most 'length versus girth' surveys show that a large proportion of women use thickness rather than length as the determining salient trait: So far so good, albeit not very scientific. So has a preference for a larger penis expressed itself historically and in evolutionary terms? There are several extremely fascinating studies that seem to bear this out:

Cambridge University Press
0521845386 - Female Infidelity and Paternal Uncertainty - Evolutionary Perspectives on Male Anti-cuckoldry Tactics - Edited by Steven M. Platek and Todd K. Shackelford

Female Infidelity and Paternal Uncertainty - Cambridge University Press

In Chapter 7, Gordon Gallup and Rebecca Burch [ SUNY Oswego - Psychology Department: Faculty and Staff ] introduce the semen-displacement hypothesis, which suggests that the morphology of the human penis may act to plunge another male’s ejaculate from the reproductive tract of his partner. Gallup and Burch (2004) documented that men’s and women’s perceptions of a male’s sexual behavior (e.g. depth, vigor, and speed of penile thrusting) change as a function of cuckoldry risk. Additionally, by utilizing prosthetic male and female genitalia, they provide evidence that the morphology of the human penis, specifically the glans penis, the frenulum, and the coronal ridge, may be designed for successful semen displacement. This chapter capitulates this hypothesis and raises some interesting predictions based on their findings.

By using the coronal ridge to create a suction mechanism, the penis is able to remove sperm already deposited in the female’s reproductive tract.

The most obvious assumption of the evolution of the male penis is female preference. That is males with longer, thicker penises are preferred to males with shorter or thinner penises by receptive females. If this were the case, then there would be evidence that females do indeed prefer big penises to small penises. According to G. Arnqvist, the penis only evolves as a result of sexual selection if the female of the species mates polyandrously(2). This would indicate that since there is evidence that the human penis evolved through sexual selection(1), that human females are polyandrous in their mating choices. Since human females are polyandrous, this leads to the assumption that there is not only intersexual selection, but also intrasexual selection. Intrasexual competition is realm where sperm competition occurs. Sperm competition explains why human testicles are so large. Chimpanzees, whose females are also polyandrous, also engage in sperm competition. However, their penises are small, when compared to humans, while their testicles are larger than humans. So what is the mechanism behind the actual size of the human penis?

There is evidence to suggest that the human penis is capable of displacing seminal fluid from the reproductive tract of human females. Length of the penis may have evolved as a way to place semen deeper in the reproductive tract of the female, making it less vulnerable to displacement(1), which would make the sperm of a male with a longer penis more likely to fertilize the female, which would make the male with the longer penis more fit. This explanation overlooks whether the female prefers a male with a longer penis. It has been suggested that the actual size of the penis has evolved through female selection, and that females have chosen larger penises over smaller penises. It bears mentioning that that the coronal ridge of the penis is shaped so that at its most pronounced point, it will come into contact with the g-spot of the female. It has also been suggested that a female who reaches orgasm during intercourse is more likely to conceive. So it may be that a penis long enough to reach the g-spot will be more likely to produce offspring, and that females may select penises that may give them orgasms.
Since males have to “persuade” females to mate with them, it stands to reason that males are going to compete against each other for the females’ attention. This relates to penis size as in an ancestral environment, males may have displayed their penises to entice females. This may be a biological reason behind male “flashing” or exhibitionism.
Since humans are bipedal the penis is a highly noticeable feature. It has been suggested that in ancestral environments, males may have been selected for bigger penises by using them as a status symbol. This would mean using penises to decide social standing. The male with the largest penis would be the one with the most power, therefore the male with the most access to females.
However, other hypotheses may be conjectured in the future which may provide a stronger case for the morphology of the penis.

see also:
Arnqvist, G. (1998). Comparative evidence for the evolution of genitalia by sexual selection. Nature 393(June 25):784. Gallup, G. G. Jr., and Burch, R. L. (2004. Semen Displacement as a Sperm Competition Strategy in Humans. Evolutionary Psychology, 2:12-23. Majerus M. E. N., O’donald, P., Kearns P. W. E. and Ireland H. (1986). Genetics and evolution of female choice. Nature 321(May 8):164-7


As for another question raised in this thread:

The Journal of Urology puts the average penis size at 5.08 inches, and the International Journal of Impotence Research puts it at 5.35 inches.

All very interesting, but what if the knob on the end your dick was simply selected for so that it wouldn't feel for women like they were being poked with a pointy stick.

For that matter maybe the foreskin was meant to protect the glans from becoming desensitized so that sex would be only "Wha.. thank you ma'm" and not the longer "wham, bam, thank you ma'm" women en masse have come to love and enjoy.

You know long lasting sex on the Serengeti plains is probably not a good idea.:biggrin1:

P.S. Bye Snoozan, again, for the millionth time.

 

[Drifterwood]

Think about it, when you walk on two legs, your eye level changes. Shame really.

 

[diamond]

Think about it, when you walk on two legs, your eye level changes. Shame really.

LMAO, god I needed that this morning, thanks for putting a smile on my face?!

 

[B_capslock]

"The descendants of the genetic upper class would be tall, slim, healthy, attractive, intelligent, and creative and a far cry from the "underclass" humans who would have evolved into dim-witted, ugly, squat goblin-like creatures.........Social skills, such as communicating and interacting with others, could be lost, along with emotions such as love, sympathy, trust and respect. People would become less able to care for others, or perform in teams.......Further into the future, sexual selection - being choosy about one's partner - was likely to create more and more genetic inequality, said Dr Curry."

This pretty much describes how los Angeles is now with the beautiful people running around while short "goblin-like" mexicans clean their bathrooms and cars. Look at Mexican TV... all of the more caucasian looking actors are the stars, while the servants are playede by the shorter, more indian looking spanish....