The more men there are with beards, the more men without beards will look attractive. The more men without beards, the more men with beards will look attractive.

That’s what a new study from researchers at the University of New South Wales in Australia suggests, contending that there is a tipping point known as “peak beard,” when hairy chins are in such abundance that clean-shaven men acquire a competitive advantage.

The study showed 1,453 women and 213 men faces where beard thickness had been adjusted. The participants were then asked about their preferences on “four standard levels of beardedness.” The authors believe that the findings confirm that rarity can be good — when they were shown fewer beards, “women and men judged heavy stubble and full beards more attractive … likewise, clean-shaven faces were least attractive when clean-shaven faces were most common and more attractive when rare.” The researchers attribute this to a basic evolutionary principle of Darwinian selection: Looking different can be an asset in sexual selection.

The researchers also released their data, and we noticed that female participants were asked about the facial hair of their fathers and partners.

The study found that women with full-bearded fathers gave higher scores to facial hair than women with barer-faced fathers. Perhaps not surprisingly, the relationship was even stronger when it came to women’s partners; the study noted, “participants whose partners had full beards gave higher ratings to full beards than women whose partners were clean-shaven.” But the effect wasn’t perfectly consistent; women still gave high scores to facial hair even when their partners were clean-shaven.

Something else caught our attention in a quote from one of the researchers: “The tide will go out again … these trends usually move in 30-year cycles from when they are first noticed.” We don’t have recent data, but a study published in 1976 did analyze beard trends over a 130-year period.

Dwight E. Robinson at the University of Washington looked at “changing modes in men’s facial barbering” using photographs published in the The Illustrated London News from 1842 to 1972. His findings on “whisker forms” suggest that beard-trend cycles might last 30 years. In 1870, 7 percent of men had beards; by 1970, 58 percent of men were bearded.

We’re still taking a closer look at the data in the recent study. What we can say now is that the research would suggest that just like several animal species, humans demonstrate “negative frequency-dependent sexual selection” (translation: rarity is sexy). That could provide some valuable clues about just why it is that men have facial plumage because as Robert Brooks, one of the study authors, explains, “We still don’t really know the primary function of the beard.”