Alcohol has calories, but I'm not sure that it would really be considered "food". For the most part it is processed like a toxin (which of course it is). But most alcoholic beverages, and certainly the "primitive" ones, contain a lot more than just alcohol. In fact, you can significantly increase the protein content of grains by fermenting them into beer...as long as you drink the yeast too. Early humans probably did; now we don't unless it's a hefe beer. So it is certainly possible that we come by our alcohol preference naturally, if the folks who drank sludgy yeast-grain glop were healthier due to the higher protein diet. Maybe...