Ian Towle & Luca Fiorenza/The Conversation For decades, small grooves on ancient human teeth were thought to be evidence of deliberate tool use – people cleaning their teeth with sticks or fibers, or easing gum pain with makeshift “toothpicks”. Some researchers even called it the oldest human habit. But our new findings, published in the American Journal of Biological Anthropology , challenge this long-held idea about human evolution. We found these grooves also appear naturally in wild primates, with little support for tooth-picking as the cause. Even more striking, in more than 500 wild primates, across 27 species both living and fossil, we found no trace of a common modern dental disease: deep, V-shaped gumline notches called abfraction lesions. Together
