The reasons I heard about us developing alcohol tolerance was that it allowed our ancestors to eat ripe fruit that had fallen from the tree and begun fermenting

The reasons I heard about us developing alcohol tolerance was that it allowed our ancestors to eat ripe fruit that had fallen from the tree and begun fermenting, with the evolutionary advantages that - they have higher calorie intake, especially if you can metabolize the alcohol into energy - the alcohol kills pathogens that might have infected the fruit otherwise - it probably also acted as a kind of mouthwash - plus, in a hunter gatherer lifestyle where resources (including food and alcohol) are scarce, the possibility addiction is probably not at all as much of a problem