Alcohol usage goes a lot deeper than as a replacement for foul drinking water in Europe. The original source that got us going was fruit left well beyond ripe, which I believe reaches a 5% alcohol by volume level at most. Humans would catalyze this into a drink.
This isn't a case of pure human folly, in fact alcohol consumption ranges across species. Bees have protocol for handling alcohol. At first if drones show back up to the hive intoxicated, they are kicked out as a warning. But if they continue to do so, the other drones will rip off their limbs.
There was a study a while back of monkeys that drink, off of Ivory Coast I believe? I could be wrong about the location but not the actual details of the study here. Tourists go to the beaches at this place and they bring drinks with them. The monkeys will run up and steal drinks from people on the beach.
The real interesting thing that they found is that the levels of alcohol consumption actually paralleled consumption rates in humans. As in the percentages of those monkeys that abstained, that drink lightly, that drank moderately, and that drank until they were rendered senseless were all the same as they were in humans. The monkeys that drank more tended to be the alphas of the group. I assume this is the case because alcohol lowers the threshold for aggression. The hierarchy correlation probably don't transfer to humans because a lot of what we judge others by is frontal lobe behavior (the very thing alcohol knocks out).
So clearly consumption of alcohol has a genetic component. Not only do we see it in families, but we also see it paralleled uncannily in other primates. But the story doesn't really end at that one substance. Substance use is actually a polymorphic trait among many animals. It's especially a trait of animals that seek novel stimuli. Considering that, it's not difficult to see why IQ has a direct correlation with substance use (yes, even alcohol). Modifying the conscious experience at the fundamental level is a difficult thing to top in terms of novelty. And no, I am not implying here that someone's substance consumption habits is an indicator of intelligence. I'm only pointing out that the connection is there.
Putting all of that together, I see substances as tools but don't really see the ones people use as dichotomous. Pretty much everyone that I know that drank alcohol also used caffeine. People who are more reserved about how they want their consciousness impacted tend to stick to things that less profoundly affect it, like caffeine. There are also cultural connotations as well. In parts of the Middle East, it's common to chew on the plant khat for its stimulant effects. It's just an animal thing, even cats like to get high.
