Darwinian process helps explain less-than-intelligent design of male genitalia

Faye:

When a new study came in the journal PNAS dealing with female preference for longer male members, I thought the topic might be a sensitive one for some readers. So I decided to hand this over to a male friend who says his sexual conquests were countless, despite being far from well-endowed by anyone’s standards.

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Higgs:

Hi. Higgs here. I’ve just finished reading this new study in the appropriately-acronymed journal PNAS. The researchers are attempting to shed light on the origin of yet another ridiculous and embarrassing fact of human anatomy – penises. While male cats are models of procreative efficiency and sexual potency, my penis retracts nicely so as not to interfere with my streamlined and graceful form. In contrast, human males have an organ that’s constantly hanging and flopping. It’s no wonder humans are thought to have invented clothes many tens of thousands of years ago. I’d cover myself if I looked like you.

According to a fascinating book by Jared Diamond called Why Sex is Fun most other apes have smaller penises – both when in use and at rest. And yet they get the job done, sometimes while hanging from a tree. So what’s with the humans?

Biologist Brian Mautz of the University of Ottawa in Canada, said that he originally thought it might be some kind of display to attract females. He got the idea from studying a creature called the mosquitofish, whose male organ stretches up to 70 percent of the length of his body.

Technically, it’s called the gonopodium and it evolved separately from the penises of mammals, but it does the same thing. Not all fish species have one, but a few go to quite the extreme.

There’s some variation among these mosquitofish, and previous research has shown that the less well-endowed males enjoy a big survival advantage because they can swim faster. If a hungry predator came by a pool of mosquitofish, the slowest ones would be most likely to get caught in my deadly claws. Did ever mention that I love fish for breakfast?

But back on topic, this fish doesn’t win a Darwin award thanks to Darwin’s other proposed facet of evolution – sexual selection – which explains why peacocks grow such beautiful tails. Females prefer to mate with the most beautiful males, even if the tails are a bit cumbersome and make them more vulnerable to predators as well. I could eat around the feathers, no problem.

Not surprisingly, human biologists were fascinated by these mosquitofish, and so they did a series of clever experiments to show that females vastly preferred the slower but showier male fish. The scientists concluded that the fish faced a Darwinian trade-off. If their gonopodia were too small, they would be unpopular and leave few progeny, and if they were too big, they’d be an appetizer for some lucky creature.

And that led Dr. Mautz to wonder if female preference might explain why human penises flop around at an unnecessary and awkward length when not in use. To investigate the human case, he recruited 105 human females to look at computerized images of nude male forms. The forms had different heights and penis lengths and body shapes. The human females didn’t know what the experiment was trying to test. They were just supposed to rate them all from 1 to 7.

And lo and behold, the ones with the longest penises were more popular by some significant margin. This does not prove that human penis length evolved through sexual selection via female choice, but it does kind of favor the hypothesis.

I hope this isn’t making any humans feel insecure. By far the most important factor determining attractiveness to women was overall body shape. Height and penis sized tied for second. And size really didn’t matter as much once the males got to some point close to average.

And there is also the delicate issue Dr. Mautz referred to as “growers vs. showers.” As far as I’m concerned, when it’s not in use it should be as well-protected as possible. When I look at human beings I realize that if evolution is an artist, it favors the absurdist style. If we look at the situation from an intelligent design perspective, we’d have to conclude that humans were designed as a joke to entertain cats. I do not subscribe to this view, but I can see how other cats are tempted to think this way.

Thank you for letting me express my thoughts.

May I have a treat now?