Swedish archaeologists, analyzing over 500 skeletons from a Viking-age cemetary, have discovered that approximately 10% of the men (mostly young), but no women, had horizontal grooves marking their front teeth. The grooves appeared in pairs or trios, and were exactly and deeply carved, demonstrating intentionality and purpose. Specialists are uncertain about the exact meaning of the tooth-carving, but it may have been meant to represent membership in an exclusive group of some sort, such as merchants, or been meant to demonstrate a warrior's ability to withstand pain. A practice common in the Americas c.800-1000 AD, this is the first discovered instance of tooth filing in Europe.

Thanks to Mirabilis for the original heads-up.