Rookie Bryce Harper, all of 19 years old, has such a poor rep already in Major League Baseball that Cole Hamels felt justified in hitting him with a fastball, and then bragging about it afterwards, as Jelisa Castrodale of NBCSports.com points out.

Apparently there could be a number of reasons to explain the visceral reaction to Harper, including a propensity toward arrogance. But could the kid’s facial hair have anything to do with it?

Sounds bizarre, but maybe.

Last January, in the journal Behavioral Ecology, two researchers, Barnaby Dixson of Victoria University in Wellington, New Zealand, and Paul Vasey, of the University of Lethbridge in Alberta, Canada, released a study on reactions to men’s beards.

They pointed out that beard growth is under genetic control, and that it may serve as a sexual signal between men. In tests, women in both Samoa and in New Zealand did not rate bearded men as any more attractive than the same men pictured without beards, so beards weren’t helping the guys get girls. But other men (women, too) viewed bearded male faces as more threatening when the pictured males adopted an angry look.

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Facial hair, the authors wrote “may intimidate rival males by increasing perceptions of the size of the jaw, overall length of the face, and by enhancing aggressive and threatening jaw-thrusting behaviors ... . The current study is the first to show that the beard augments a threatening behavioral display as bearded men with angry facial expressions received significantly higher scores for aggressiveness compared with clean-shaven faces ... . This suggests that the beard plays an important role in intermale signaling of threat and aggression.”

Other, past studies, have shown that when mock juries are presented with pictures of men accused of crimes like rape, the juries are much more likely to believe the bearded man is guilty. A 2004 study from researchers at Montclair State University in New Jersey asked 371 people to “sketch the face of a criminal offender. Eighty-two percent of the sketches contained some form of facial hair.” Yet beards have often been seen a sign of maturity, education, and competence. So what’s up?

A man’s facial features have been shown to reflect both his androgen status -- how much testosterone and related hormones he’s making -- and physical strength. Beards, themselves dependant upon androgens, can frame and accentuate those features.

This could be positive. “Both men and women ascribe positive attributes such as intelligence, courage, confidence and social maturity to beards,” Dixson explained in an email. But in his study, he included the angry expressions, and then, the beards made the men look threatening and meaner than when the same men were clean shaven.

So it’s all the above, suggested Dixson. “Beards appear to be linked with perceptions of elevated age (maturity), social status, dominance and threatening facial displays.”

Whether or not it’s deliberate strategy, the rash of beards among athletes, most famously Brian Wilson of the San Francisco Giants, is one way to intimidate the opposition. The callow Harper is just playing along.

Brian Alexander (www.BrianRAlexander.com) is co-author, with Larry Young PhD., of "The Chemistry Between Us: Love Sex and the Science of Attraction," (www.TheChemistryBetweenUs.com) to be published Sept. 13.

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