For anyone who's ever wondered why some of us have too many teeth to fit into our mouths (hello, braces and wisdom teeth extractions!), a new study could clear up some of the speculation.
The research, published in the journal Proceedings of the National Academy of Sciences, suggests that our modern-day diets might explain why some people have overcrowded teeth.
The study found that because humans have shifted away from a "hunter-gatherer" diet to a more pastoral way of eating, our jaws have accommodated for this change by growing shorter, LiveScience reported. This could, in turn, lead to teeth overcrowding.
"This research shows the interaction between what is fundamentally a cultural behavior, farming, and its effects on our anatomy," study researcher Noreen von Cramon-Taubadel, of the University of Kent, told LiveScience.
Discover magazine reported that researchers examined 3-D images of 295 mandibles (lower jaws) and 322 craniums that were collected from 11 different human tribes from around the world. Of those tribes, six were farmers and five were hunter-gatherers, Discover reported.
Researchers didn't find a link between the craniums and the type of tribe (hunter-gatherer or farmer), but they did find a strong link between the mandibles and the type of tribe, according to Discover.
BBC News explains why exactly the changes in jaw size are linked with the kinds of food we eat:
... The changes in human skulls are more likely driven by the decreasing bite forces required to chew the processed foods eaten once humans switch to growing different types of cereals, milking and herding animals about 10,000 years ago.
"As you are growing up... the amount that you are chewing, and the pressure that your chewing muscles and bone [are] under, will affect the way that the lower jaw is growing," explained Dr von Cramon-Taubadel.
Overcrowded teeth may be a result of extra teeth, abnormally shaped teeth or impacted teeth, among other factors, according to the National Institutes of Health. A dentist will refer a person to an orthodontist for tooth removal, reshaping or other treatments if the overcrowding is causing problems.