I saw a program on the Discovery Channel several years ago that followed a colony (or whatever a group is called) of either baboons or monkeys for a whole year. It was compressed into a one hour program but at one point in the season, apples or some other fruit ripened and fell from the tree and began to rot on the ground. This would lead to natural fermentation from the heat, sugar, and yeast. The baboons would eat the fermenting fruit and get drunk. The film footage of these drunk baboons staggering around and finally falling down to pass out and sleep it off was really hilarious. Seems like it was in the Kalahari.