Chances are, in one or some or lots of bars across America tonight, guys will gather to tie one on in celebration of Zach Galifianakis' birthday. The Hangover franchise star turns 45 today.

But outside such “special” occasions, it turns out, guys might have another reason to drink too much: the simple desire to share in others’ emotions. Alcohol makes it easier to do just that, a new study finds, letting guys more easily "catch" a smile from their drinking buddies and enjoy the feel-good moments that come from social bonding.

The study, in the journal Clinical Psychological Science, looked at alcohol's effect on “emotional contagion,” basically how easily members of a group pick up on and share in one another's feelings. It's a process that leads to social cohesion among the group—something a lot of folks yearn for.

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In the study, participants were divided into three groups: they were given a cocktail, given no alcohol, or given a nonalcoholic drink they were told had booze in it. Perhaps not surprisingly, sober males were far less likely than female participants (sober or not) to catch a smile from another group member. But among males who had a cocktail, that gender difference was erased.

In fact, in the all-male groups, drinking raised the likelihood of smile-sharing by 30% over that in sober all-male groups. Alcohol had little effect on all-female groups; smile-sharing was pretty much the same whether sober and drinking. And for all groups, the higher the likelihood of mutual smiles, the better the participants felt.

Overall, the researchers note, men show “dramatically higher rates of alcohol-related problems” than women; they’re also “50% more likely than women to binge drink and twice as likely to report symptoms of alcohol abuse and dependence.”

It seems drinking may let guys feel the joy that others feel—and that, unfortunately, may be enough of a reward to risk waking up with a Hollywood-blockbuster-size headache the next day (or that Mike Tyson face tattoo).

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