Women everywhere are asking, What are men like Congressman Weiner, Brett Favre, Greg Oden, and Kanye West thinking when they send us photos of their manhood? The answer is that men aren't thinking at all, they're compelled by an unconscious, evolutionary urge inherited from our primate ancestors: male monkeys and apes routinely display their penis to females to indicate sexual interest. In other words, it's a very natural urge; of course, so is burping, but most men are able to restrain their sonorous belches around the ladies.
Primatologist Frans de Waal writes in Peacemaking Among Primates:
Since bonobos can sheath their penis, nothing is visible most of the time. When the organ does appear, however, it is not only impressive in size, but its bright pink color makes it stand out against the dark fur. Males invite others by presenting with legs wide apart and back arched, often flicking the penis up and down—a powerful signal.
Men, it seems, emulate their bonobo brethren: the Internet is saturated with self-portraits of penises snapped by men from every nation on Earth. Our research for Billion Wicked Thoughts revealed that one in four webcams on the free webcam network ChatRoulette are aimed at a penis. On the adult networking site Fantasti.cc, 36 percent of men use an image of a penis as their avatar; only 5 percent of women use a vagina. On Reddit's heterosexual Gone Wild forum, where users are free to post NC-17 pictures of themselves, 35 percent of images self-posted by men consist of penises.
In fact, male exhibitionism has long been understood by clinical psychologists as a non-dangerous compulsion: men who flash their organ to strangers rarely seek contact afterwards, instead describing a powerful sense of relief from the display alone. Lance Rentzel, former wide receiver for the Dallas Cowboys, recounts the incident that got him arrested:
The act was more magical than sexual, a ritual to restore that all important sense of power that the defeats of life had temporarily destroyed. On this day, for some reason, I needed someone to play with me in a childish game I was making up. Look at me, look at me. Look at what I've got. I sat in the car and they came over and I exposed myself. It took maybe 10 seconds, then I drove off, strangely relieved.
The male exhibitionist impulse seems to be similar to the ancient primate urge to groom evinced in girls' enjoyment of combing one another's hair. Or, perhaps, similar to the urge to yawn (but remember to cover your mouths or other parts, gents!) Men's desire to show their penis is only matched by men's equally natural urge to look at other men's penises, according to our research.
Though civilization and decorum (not to mention women's understandable resistance) have rendered it bad taste or even criminal for a man to display his member, men still retain the neural circuitry of our ancestors, imbuing them with the primate instinct to display their own penis, and to attentively monitor the displays of other men. So, gentlemen, if you feel the urge to send a photo of your junk, you shouldn't feel guilty. It's perfectly natural. Just know this: the evidence overwhelming demonstrates that most women don't share your enthusiasm. In fact, there aren't many places where the gap between male and female sexual interests are wider. Instead, consider sending flowers.