What is it with this anti-beard sentiment? Here’s an article that wonders why so many scientists have beards, with several amusing stories.
But anti-beard arguments also ran rife in pre-Victorian times: Beards trapped food and the stuff you spewed out when you sneezed. At a stretch, they could even go as far as to catch fire and trap vermin, some argued. This all came to a head in 1907, with a rather remarkable experiment. A French scientist took one bearded and one clean shaven man from the streets of Paris and asked each of them to kiss a woman, whose lips were previously swabbed with antiseptic. After each smooth, her lips were swabbed and the the cultures were smeared on agar. The hairy kiss, it turned out, was by far the more microbial-ly diverse.
That anecdote answers the question right there. Overgrown nerds experience very little risk of ever having to kiss French women on the streets of Paris, so there is very little selection against beard growth. Hey, if I had some likelihood of sweeping strange women into my arms, I might shave, too … and brush my teeth more than once a week, and take a shower more often than once a month, habits atypical of us hairy, dirty, microbe-rich men.
(via Pure Pedantry)