Penises come in all shapes and sizes, but one thing they all have in common is a toadstool-like head known as the glans. This sex organ may look weird, but there’s actually a very good reason for its mushroom shape.
Researchers led by Gordon Gallup found that the ridge on the top of the penis is designed to scoop out other men’s semen from the vagina during sex. This is what experts believe caused the fungus-like shape of the tip.
The tube shape
When you look at your own penis (please don’t do this in public or without the other person’s permission) or even just pictures of someone else’s, you may notice that it has a particular mushroom shape to the top portion, known as the glans. Scientists have a few theories about why the glans is shaped like that.
First, it helps the penis stand up in the vagina when you are erect. It also makes it easier for sperm to reach the egg and get impregnated.
The glans is connected to the shaft of your penis by a piece of tissue called the frenulum, which looks a bit like a small tab of skin at the bottom of the head. This part of the penis is often sensitive. It is usually covered by foreskin, which most people lose when they are circumcised.
On average, human penises are about five to seven inches long when erect. However, the size of your flaccid penis (when it is soft) doesn’t have much to do with how big it will be when hard.
In this collection of playful, conversational essays (adapted from columns in Scientific American and Slate), research psychologist Jesse Bering investigates why certain human traits evolved the way they did. He tackles topics ranging from the evolution of masturbation to why we love cannibals, and explores what it means to be human through a variety of scientific lenses.
The mushroom shape
If you’ve ever wondered why your (or the President’s) dick is mushroom shaped, you’re not alone. It’s been the subject of much speculation, with some suggesting that the shape evolved to scoop semen from rival males. But, is this really the case?
According to evolutionary psychologist Gordon Gallup, the human penis is an impressive “tool” that’s designed for a specific purpose. He calls it a “mushroom-shaped phallus” because of its bulbous head and coronal ridge, which looks like a mushroom’s cap and forms a rounded brim where the head and shaft meet.
Gallup’s research suggests that the glans penis is shaped this way to serve as a displacement device, with its ridge helping to scoop out sperm from other men, thus improving the chances of its own partner getting fertilized. He conducted a study with fake penises and a cornstarch-like semen mixture to test this theory, and found that the mushroom-shaped glans was able to scoop out about 90 percent of the mixture.
However, he warns that not all glans are shaped the same way. Rather, the shape and size of your dick is determined by the combination of genes on your X and Y chromosomes. Consequently, some people have larger glans than others and it’s all normal. In fact, a bigger glans can actually make for better sex in some cases.
The ridge
It’s not something we spend a lot of time thinking about but, like it or not, your penis does have a very specific shape. That mushroom bit at the end, called the glans penis, looks rather like a coronal ridge – and there’s actually a very good reason it’s shaped like that.
The theory is that the ridge evolved as a sort of semen displacement device. Back in the day, it was common for women to have sex with multiple partners so that they could increase their chances of getting pregnant, and the glans penis helped to remove the sperm from other males from the woman’s vagina. The ridge on the glans penis allowed it to scoop out the sperm more effectively than a straighter, longer penis would have done.
A team of scientists from the State University of New York did some experiments with latex phalluses and artificial vaginas in 2003 to test out this theory and they found that the ridge at the end of the glans penis really did work as a semen displacement tool. It was able to scoop out more than 90 per cent of a mixture of water and starch, which they designed to have a similar consistency to semen, with just one thrust.
The results of these experiments, published in Evolution and Human Behavior, suggested that the ridge at the head of the glans penis removed any semen from another male that might already be present, so it didn’t have the chance to fertilize a competing sperm in the woman. This is just one of the many theories for why our phalluses are shaped the way they are, but it’s a good one and there’s no doubt that a glans penis with a ridge on it is a very useful thing indeed.
The tip
The penis’ tip, known as the glans, is shaped like a mushroom with a coronal ridge. It’s also thinner at the head than at its base, which gives it a cone shape that’s great for anal penetration. This elongated lump of skin, muscle, veins, and blood has given pleasure to many a partner over the years.
It’s been argued that this shape was an evolutionary adaptation to help displace other men’s semen from the female vagina in order to increase a man’s chances of fathering a child. The ridge is supposed to scoop out any other male’s sperm, and it’s reportedly more effective than the testicles of other animals that have similar shapes.
This theory isn’t necessarily based on hard evidence, though. As with all evolutionist theories, it’s not always possible to know why certain traits are shaped the way that they are. It could be that the glans has a specific structural function, but it’s equally likely that the shape was just a byproduct of some other adaptations. Still, it’s intriguing to think about how our ancestors may have solved the problem of getting their own sperm into women’s reproductive tracts in order to reproduce themselves. And while the dick might not be the most attractive part of a guy, it sure is functional!