President Coolidge and Semen Quality
Calvin Coolidge was the 30th President of the United States. He succeeded to the presidency in 1923 after the sudden death of Warren G. Harding, and is most well known for his response to the Boston Police Strike, whatever that was.
But among biologists and sex researchers, he’s famous for another reason altogether.
One day, President Coolidge and the first lady were being shown around an experimental government farm, because that’s how you spend your Tuesday mornings when you’re the leader of the free world. As Mrs. Coolidge passed a chicken coop, her eye was drawn toward a particular randy rooster. She noticed that the cockerel was copulating with a mad frenzy.
“How often does he do that?” she asked an attendant.
“Oh, dozens of times a day, Mrs. Coolidge,” he replied.
The first lady, perhaps lamenting the POTUS’s infrequent conjugal visits, ordered the attendant to “Tell that to the President when he comes by.”
The attendant did as he was told. The President eyeballed the libidinous chook before asking, “Is it the same hen every time?”
“Oh, no,” laughed the attendant. “It’s a different hen every time.”
“Tell that to Mrs. Coolidge,” said the President, flouncing off with what I only imagine must have been a very smug look on his face.
I think it’s unlikely he received an invitation to Mrs. Coolidge’s “oval office” that night.
The Coolidge Effect
Anyway, why am I telling you this? Because this anecdote inspired what is now known as the Coolidge Effect, the observation that males are sexually excited by novel partners and reluctant to repeatedly mate with the same female.
The effect was first observed in rats. It happens in snails too. But it may also apply to humans. The idea is that females need time to brew a sprog, pop it out, and go through all that lactation business before they’re ready for another crack at pregnancy. Males, meanwhile, are good to go again after a brief nap. Evolution hit upon a neat answer. Rather than men hopping around the female who is gestating their progeny, yelling “Come on! Hurry up!”, males could instead pursue other females, knock them up too, and, ideally, recruit a sizeable harem and operate some sort of sexual merry-go-round.
Paul Joseph of the University of Florida wondered whether the Coolidge Effect might influence biology as well as behavior.
He had 21 men report to his lab every two or three days. While there, the men locked themselves in a private room and then (there’s no easy way to say this) they watched a clip from a porn movie and masturbated into a jar.
Each time they visited the lab, they saw a different clip. The first six times, the clip featured the same female performer. On each man’s seventh and final visit to the lab, he saw a clip featuring a novel performer.
Joseph analysed the quality of the men’s semen. He found that there was no change in motility, concentration, and volume over the first six sessions (when the performer was the same). But when the men watched the novel performer, they produced more semen, with more motile sperm, and they ejaculated faster.
The Coolidge Effect does appear to have an impact on a man’s sperm quality. Men aren’t just more excited by the idea of a novel sex partner, we produce the goods to back it up. And, yes, this research does seem to imply that if you’re a man who suffers from a low sperm count or subpar motility, you might want to argue that your doctor should give you a prescription for a stack of porn. If you’ve got the balls to ask for it, good luck to you.
Joseph, P. N., Sharma, R. K., Agarwal, A., & Sirot, L. K. (in press). Men ejaculate larger volumes of semen, more motile sperm, and more quickly when exposed to images of novel women. Evolutionary Psychological Science. Read summary
For an audio version of this story, see the 25 August 2015 episode of The Psychology of Attractiveness Podcast.
