As I will be going through an unfortunate and unavoidable wisdom teeth extraction on Monday, I've decided to examine exactly why humans develop wisdom teeth. Some think the teeth were an evolutionary answer to a diet comprised mostly of foliage. Our stomachs are not developed to grind up nuts, leaves, berries, roots as well as some animals are. All these foods require greater chewing power and may cause more wear on the teeth.
Interestingly enough, some populations of people have a greater chance of developing wisdom teeth than others. The Bantu speaking people of southern Africa have a 99.8% chance of developing wisdom teeth while indigenous peoples of Mexico have a 0% chance of developing them. This lends support to the diet theory.
I am not quite sure I subscribe to the diet theory. People would have still eaten just as much as they do now as they did back then and should of had problems with cleaning the wisdom teeth and getting them to form in the mouth correctly. I guess we will never truly know.