Wisdom teeth are no longer needed because they are vestigial organs. This means that they don't have any real purpose and are simply leftover relics from our evolution. They used to be useful for our ancestors who had a diet that was mostly tough and chewy foods. The wisdom teeth helped them to grind these foods down so that they could be swallowed and digested. However, modern diets are much softer and easier to eat, so we don't need wisdom teeth anymore. In fact, they can even cause problems like overcrowding in the mouth or impaction (when the tooth doesn't erupt properly). Therefore, it's generally recommended that wisdom teeth be removed before they cause any problems.