Paleoanthropologists have wondered how and why humans evolved molars that emerge into the mouth at specific ages and why those ages are so delayed compared to living apes. It is the coordination between facial growth and the mechanics of the chewing muscles that determines not just where but when adult molars emerge. This results in molars coming in only when enough of a ‘mechanically safe’ space is created. Molars that emerge ‘ahead of schedule’ would do so in a space that, when chewed on, would disrupt the fine-tuned function of the entire chewing apparatus by causing damage to the jaw joint.