An intriguing new paper in PLoS ONE by Haselhuhn and colleagues suggests that men with wide faces make you selfish. No… really. The explanation is simple: {taking a deep breath now} since men with wide faces are more aggressive, less-trustworthy, and more prone to engage in deception (that last one is my favorite!) it is indubitably beneficial for you to assume that any wide-faced dude is dubitable, and for you to preempt said presumed onset of selfish behavior with—you guessed it—selfish behavior. Fight fire with fire.

One possible explanation, the authors propose, is that this vicious circle—this sardine that bites its own tail—is a self-fulfilling prophecy. That is, because you assume that the fat guy is selfish (you might wonder: perhaps this chow-champ wants a bigger piece of the pie?), it follows logically that you must protect your interests, which then does not go unnoticed by your wide-bodied companion, prompting selfish behavior.

The authors start off by testing the premise: wide-faced guys are indeed prone to selfish behavior, tested with a battery of economic games. Check: proself behavior confirmed. And not just competitive behavior, they maximized their irrespective of their opponent’s resources. Then they asked random people to play the same games against an opponent represented by a photo of a face characterized by its width-to-height ratio. They found that people only acted selfish when they were playing against a wide-faced male.

But what does it mean now that I recently changed from morbidly obese (wide-faced) to healthy-weight (less-wide-faced). Am I less selfish now, or are you?