[bane]

I can kind of see alcohol being a powerful evolutionary mover: water sources are frequently contaminated, killing off lots of drinkers, and the kinds of biological contaminants frequently are more deadly in the young, (yes animals get sick from drinking dirty water just like people) while alcohol can be a decontaminant and is often present with hydrating water as well as other nutrients and energy sources (like fruit) keeping drinkers of both alive maybe long enough to reproduce.