It really annoys me the way a lot of people picture evolution. The genetic mutations happen before the need is realized. If mutation helps a species survive in it's environment, the gene is carried on through natural selection.<p>An endless supply of teeth has no environmental advantage in the modern western world. The loss of an adult set of teeth does not inhibit an individual from eating or mating.<p>However, it will be interesting to see what genetic mutations carry on in the developing world assuming it never attains a western standard of living.