Wider faces = more aggressive: evidence from the NHL

The Economist reports on a Canadian study that claims that men with wider faces are more aggressive. The hypothesis is that both characteristics are caused by high testosterone levels at puberty, which is why they're linked.

For evidence, the authors looked at NHL players, and found that the wide-faced guys had significantly more penalty minutes than their narrow-visaged teammates.

The article doesn't link to the actual study, and there's one obvious question it doesn't answer. Isn't it possible that aggressiveness by wide-faced people is just learned behavior? Men with wide faces tend to be bigger men in general, and bigger men might be more aggressive because, with their strength and size, they can get away with it.

Hat tip: Tyler Cowen