The biology of human body is extremely fascinating – right from how a woman’s body reproduces an entire human being to how each organs function in harmony with each other for our system to work. But what has recently caught our attention is why the penis is shaped the way it is – like a mushroom. Penis plays a role of an important tool when it comes to reproducing, but that’s not it. The tube shape makes sense as it can comfortably fit inside a vagina but what about the bit at the top. Technically called glans, is shaped a bit like mushroom and there’s an evolutionary reason for the shape.
Professor Gordon Gallup from the State University of New York led a team of scientists to investigate the anatomy of the human penis and its use in 2003. The evolutionary reason for the shape of the head of the penis is there to allow it to scoop out other men’s semen from a woman’s vagina during sex. Surprised? But it is a fact. Experts believe the penis evolved to have a ‘ridge’ to spoon out the semen of love rivals, giving them an advantage when it comes to getting a woman pregnant.
In an article published in the journal Evolutionary Psychology, Gallup argues that ‘a longer penis would not only have been an advantage for leaving semen in a less accessible part of the vagina, but by filling and expanding the vagina it also would aid and abet the displacement of semen left by other males as a means of maximising the likelihood of paternity.’ The theory is, it’s about the survival of the fittest.
Sperm cells can survive in a woman’s cervical mucus for up to several days. Over this period of time, if she has more than one male sexual partner (within 48 hours), then the sperm of these two men are competing for reproductive access to her ovum. Hence, the nature equipped men with penis sculpted in such a way that organ could effectively displace the semen of deposited by a sexual rival from their partner’s vagina, a well-synchronised effect facilitated by the ‘upsuck’ of thrusting during intercourse.
To explore the theory, scientists conducted an experiment. They put a mock-up penis with a sizable ridge into a fake vagina and measured how much of a corn starch mixture it could pull out, compared to a fake penis with no or smaller ridge. They found that the penis with the massive ridge was able to remove 90% of the corn starch mixture with just one thrust. The scientists also discovered that the depth of thrusting was important. A three-quarter thrust could only remove 40% of the semen mixture they created.
Gallup also said they found evidence that couples tend to have more energetic sex if the woman has been suspected of cheating or if a couple has been apart. It could, he said, be down to a sub-conscious desire to rid his partner of any trace of another man’s semen. However, it is important to note, the theory dates from centuries ago when women would have sex with a number of partners, to increase their chances of getting pregnant.