Have you ever wondered why people still grow wisdom teeth despite the fact that dentists regularly pull them out? According to a report from CS Monitor, a recent study from scientists at Monash University in Australia suggests that our third molars, or wisdom teeth, are smaller than other hominin species’ for a much simpler reason than previously thought.

The difference between modern humans’ wisdom teeth and early hominin species’ is significant – our ancient ancestors had up to four times the chewing surface area in their mouths than that found in a modern human.

For years, researchers believed that the shift in wisdom tooth size occurred as a result of cultural and behavioral changes, like the development of cooking. The recent study, however, suggests that the reason for the downsizing is not so complex.

According to evolutionary biologist Alistair Evans from Monash University, “Teeth can tell us a lot about the lives of our ancestors, and how they evolved over the last 7 million years.” Fossil evidence shows that the size of the third molar steadily decreased up until modern times, but the reason is rooted in biology rather than culture.

The study states that the changes in molar size are influenced by the “inhibitory cascade,” a general rule that describes how the size of one tooth influences the size of the teeth next to it.

“Whereas selective pressures emphasizing function, such as changing bite force, have been used to explain the variation in tooth proportions, only by including development can one explain the details of the changes,” researchers wrote.

“By providing a development-based expectation for the evolution of the hominin dentition, the inhibitory cascade framework moves this research towards a predictive science, further testable with additional fossils.”

The study suggests that as modern humans developed their third molars would have grown smaller with or without developments in culture and cooking practices. The researchers were surprised to learn that human evolution was much simpler than they previously thought.

A press release describing the details of the study can be found here.