A study of skull growth and tooth emergence reveals that timing is everything

Six, 12, and 18. These are the ages that most people get their three adult molars or large chewing teeth towards the back of the mouth. These teeth come in at a much later age than they do in our closest living relative, the chimpanzee, who get those same adult molars at around three, six, and 12 years old. Paleoanthropologists have wondered for a long time how and why humans evolved molars that emerge into the mouth at these specific ages and why those ages are so delayed compared to living...