If you have ever wondered why the Penis is shaped the way it is, then this article is for you.
A team of scientists led by evolutionary psychologist Professor Gordon Gallup of the State University of New York at Albany theorizes that sperm competition played a significant role in the evolution of the penis, particularly the glans.
According to the semen displacement theory, the bell-end shape of the penis evolved as a means to draw out and displace foreign semen away from the cervix. This was during the time in our evolution when double-mating was the norm to propagate the species.
In order for a male to have the best chance of fertilizing a female with his sperm, his penis gradually developed the coronal ridge found on the glans to drag semen from other males out of the vagina as he withdrew.
To test the theory, the scientists simulated sexual encounters using artificial models with different-sized glans. Using a cornstarch mixture and a fake vagina, it was discovered that the penis with the larger ridge was able to remove up to 90% of the cornstarch mixture with just one thrust. The scientists also observed that at least 75% of the penile shaft must be inserted in the vagina to get the maximum results.
Vigorous pelvic thrusting also plays an important role. According to data, stronger sexual desires in males are more apparent after a couple is separated for a period of time, such as when the male is out of town or on a business trip (or away hunting, in the ancestral past).
Since males cannot monitor the female’s sexual behaviors in his absence, the subconscious knowledge that the female might have been fooling around influences his vigor in lovemaking once he returns. This arousal response has gradually developed over time and has influenced human behavior for countless generations. The longer the separation, the stronger the arousal. The deeper he thrusts, the more semen he can displace and the more powerful his ejaculations that land deeper in the vagina. This not only makes it more difficult for the next male to displace his semen but it also makes him more likely to be the winner in the baby sweepstakes.
Modern culture tells us that humans tend towards monogamy but obviously, this hasn’t always been the case. Polygamy is still practiced in various cultures and scientists estimate that of the more or less 4,000+ animal species, only three to five percent practice any form of monogamy.
Once ejaculation has taken place, the average male will turn flaccid almost immediately. This is significant, as further thrusting would mean removing his own sperm and ultimately be self-defeating.
Predictably, the theory wasn’t readily accepted and was greeted with disgust, if not indifference. While the “unspeakable” nature of an inquiry into the evolution of the male glans makes people uncomfortable, self-reflection even in an unflattering light is key to understanding ourselves and our behavior.