This is a special kind of silly. Colas, beers, wine, liquor and on and on. These are just beverages like milk with various properties and tastes. Saying humans shouldn't drink cow's (or goat, et al) milk is like saying humans shouldn't eat bamboo shoots because pandas eat bamboo . That really applies to any food for that matter. No sugar, no colas and so on. We should only drink water I suppose.