This is only partly true - much like another popular rumor about the 10%-capability of brain usage or the one that eskimos have 100's of words for snow, etc. The lactic enzymes prevents undesired "side effects" when consuming milk, but they are not an "antidote" against "milk-poisoning". Many animals (some better than others) can digest milk, just not as fast as it could have been done with enzymes like lactase. I've grown up in a village and have seen adult cats drinking a little milk and eating bread leavened in milk without having any visible reactions against it. Besides, Caucasian people are not the only lactose-tolerant human race - there are Saharo-Nilotic pastoral people who have also developed genes that allow them to consume milk without "side effects".