Have we finally reached "peak beard?" Social scientists who study the waxing and waning of men's facial hair have been predicting for more than a year that the profusion of beards on hipsters, athletes, actors, and other trendsetting males would soon reach its height, and then go into steady decline. The turning point seems to have arrived. House Speaker Paul Ryan, a straight-arrow conservative whom no one would mistake for a craft beer brewer from Portland, grew a beard a few months back, becoming the first speaker to sport whiskers since 1925. When he was widely mocked — "What is Paul Ryan thinking?" asked National Review — he shaved. A host of once furry actors have also shown up shorn in recent weeks, including Brad Pitt, Matthew McConaughey, Ben Affleck, and George Clooney. Why? "Negative frequency-dependent sexual selection," of course.

Men grow beards, social psychologist Robert Brooks explains, as a form of plumage. The display of facial hair advertises a man's virility to prospective mates and rivals, and helps him stand out from the crowd. It's an effective strategy, until lots of other men conform to the nonconformity. "Beards gain an advantage when rare," Brooks says, "but when they are in fashion and common, they are declared trendy and that attractiveness is over." Indeed, a 2013 Australian study found that when a majority of men are bearded, women begin to find shiny, clean-shaven faces more attractive. What does this tell us? Something yet undiscovered by the young, but obvious to those who've been through a few fashion cycles: What is cool today will look comically affected tomorrow. The image you carefully cultivate at one point in your life will make you cringe in embarrassment years later. If you don't believe me, let me show you my photos from age 28, when I was rocking a (unironic) mustache. I thought it looked rather rakish at the time.