Very few can tolerate the number of dairy servings recommended. Lactose is a sugar found in milk that can be problematic for many individuals. Lactose intolerance occurs because many people lack the enzyme lactase that is responsible for breaking down milk sugar. But some dairy proponents think concerns about lactose intolerance are overblown. PCRM is making a big deal out of lactose intolerance and minorities.
All adults develop bacteria to digest milk.
You get used to it eventually. For lactose intolerant individuals this is hardly comforting advice. There is no evidence I know of that suggests lactose intolerant individuals harbor a bacterium that will take over where their bodies left off. Ask anyone who can't digest milk. The punishing effects of lactose intolerance are unmistakable.