The reason why people have overbites(Your top part of you jaw overlaps the bottom half) is that we use forks. About 200 years ago, when forks started to be used all the time by Americans in the west, people started to develop overbites. The same thing happened with the introduction of chopsticks 900 years ago in China. When pots were introduced, allowing people to drink food such as soups without chewing, the teeth of people started to decay. Pots, pans, forks, and knives are the reasons why we have to go to the dentist. The food we eat isn't as tough. It's cut up into small pieces first. Teeth aren't even needed for human survival now that we can even drink our food.