The other title of this post is “what happens when you leave a guy alone on a desert island for a few weeks”, and the other OTHER title of this post is “people who are obsessive enough to measure their body hair”.
But what, you may ask, is the real title of the PAPER?
ResearchBlogging.org Anonymous. “Effects of sexual activity on beard growth in man.” Nature, 1970.
Historical science is often so awesome and so crazy, in so many ways. This paper comes to me courtesy of Monica at Purdue, and to her courtesy of Dr. John Anderson’s Endocrinology class (Bio 559) at Purdue. The more I see of the syllabus, the more I REALLY wish I had a) gone to Purdue, and b) taken this class. Because I think I might have been studying endocrinology today.
Aside from being some wacky science, this paper earns additional wackiness from being self-performed, as well as being a self-performed measurement of facial hair. And, considering it was a case study, he did some good controls, and kept some very good data. I’m pretty impressed.
Also, this is an example of a good quote I heard from the Nature podcast a while back. “The best discoveries happen not when you say ‘eureka’, but when you’re staring into a microscope and say ‘hey, that’s funny…'” And when you spend a lot of time alone on a desert island, you have a lot of time to notice things that are funny.


I’m not really sure what the author was doing on this desert island, as he remained anonymous, though vouched for and willing to respond to reviewer comments. My theory is that he was a researcher of some other bent than endocrinology (maybe a botanist or marine biologist or something if it involved desert islands), and that he thus remained anonymous because he was reporting findings out of his area of expertise. But he’s definitely got how to do an experiment down, though he is very limited in that he was forced to perform it on himself.
So he’s on this desert island, apparently for several weeks at a time, and apparently very lonesome for fair female company. And he began to notice differences in his facial hair. In fact, he noticed a cycle. His beard grew at a relatively slow rate while he was alone, but when he was able to see his lady friend, he noticed a sudden increase in stubble.
So how does one measure one’s facial hair growth? I’ve got this amusing image in my mind of a guy craning his neck in a mirror, trying to get the angle of the ruler just right. But no. This is another point where you could tell this guy had science on the brain. He shaved at the same time every day, and weighed the results. I wonder if he saved his samples…how would you explain that? Anyway, he noticed a clear pattern, with increases in the weight of shavings around the time he was gettin’ some action. The increase occurred only during the first day, and then dropped off to baseline levels over a period of 4-6 days.

You can see the results of 22 days of measurements above. The female symbol represents the times when the author had access to a female, while the isolation period was the island. And there’s a definitely spike there. He took several weeks of measurements, during which he only saw his girl on the weekends, to obtain a graph with some error bars. He did notice that other factors, such as tension, fatigue, and even drinking appeared to affect the amount of hair produced on a given day. But he decided to look at levels of androgens (testosterone and other closely related hormones), because he knew it was under “testicular control” (heh heh), and as…other functions, are also under testicular control, a correlation seemed likely.
So he played around on the desert island, dosing himself with hormones which he placed under his tongue. He included a round of placebos, and tested testosterone, cortisone, and androsterone. He was able to show that all of the hormones tested produced increases in beard growth, with androsterone producing the best effects (unfortunately, there’s no graph).
His findings are not really surprising in light of what we know now. There are known increases in androgens in response to sex. Not only that, men who have been separated from their significant others for some period of time will exhibit spikes in their androgen levels AND in their sperm counts when reunited with their favorite lay. Unfortunately, I don’t think studies of this kind have been done in women, and they would certainly be a good bit more difficult, as women’s hormone levels fluctuate in a cyclical rhythm which you would have to control for, as well as controlling for when they saw their mates, and you would have to test them in every stage of their cycle…yikes. Still, the outcome could be interesting.
So what was his conclusion? That hormone activity in men could be measured by simply weighing a guy’s beard shavings from one day to the next, rather than doing things like taking urine samples. A good idea. But I am thinking of more practical applications. If you like some stubble on your man, make him wait for it. It will make that 5 o’clock shadow all the better.
Anonymous (1970). Effects of sexual activity on beard growth in men Nature, 226, 869-870