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Scientists Think Your Canine Teeth May Have Originated For Sex

Why do herbivores and omnivores have such sharp teeth? All the better to attract mates, according to this fossil study.

by Samantha Cole
Nov 14 2016, 9:18pm

Skull of a dinocephalian therapsid. Image: Lauren Mulligan/Wits University

Paleontologists are beginning to wonder if cuspids — also known as canines, or eye teeth, those fangs in the upper jaw — played a more complicated role in evolution than just tearing up chunks of prehistoric meat.

A study published in PLOS ONE looks at the cuspids of our ancestors from way, way back: The 300 million year old pre-mammalian therapsids, a point in evolution where teeth began to separate into distinct types. Long, sharp canine teeth were thought to be useful in hunting or fighting, but their presence in herbivorous mouths posed a problem. What would peaceful leaf-eaters do with sharp teeth?

Modern-day walruses and muntjac deer use theirs to seduce mates and intimidate threats, and in many species, these teeth are much larger and more pointed in males than in females. This study of a Choerosaurus dejageri fossil, an early mammal-like reptile that eventually led to mammals, shows that its canine teeth were most likely full of nerves and veins. These teeth were pretty useless in a fight, but sensitive and impressive enough to lure a mate.

Fossilized skull of a Choerosaurus dejageri. Image: Julien Benoit , Paul R. Manger, Vincent Fernandez, Bruce S. Rubidge/PLOS One

Tracing this trait back "hundreds of millions of years before mammals or the more advanced dinosaurs expressed these behaviours," lead author Dr. Julien Benoit says in a press release, could reshape how scientists understand evolution and sexual competition. It could also finally explain your friends who find pop culture vampires inexplicably attractive, pointy fangs and all.

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