Catlin was convinced that the habit of sleeping with their mouths closed contributed to the development of the Native Americans’ fine teeth and beautiful faces. “An Indian child is not allowed to sleep with its mouth open, from the very first sleep of its existence; the consequence of which is, that while the teeth are forming and making their first appearance, they meet (and constantly feel) each other; and taking their relative, natural, positions, form that beautiful and pleasing regularity which has secured to the American Indians, as a race, perhaps the most manly and beautiful mouths in the world.“