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Early stone tools, like knives and scrapers, are easy for anthropologists to learn about because these items are still around. Even after two million years, a chipped stone tool is still going to be there when you dig it up. Toothpicks, however, are another story. Made from splinters of wood, thorns, or bone fragments, these can rot and crumble³ away over time, leaving no recognizable trace. If this is so, how can an anthropologist² look at a two million year old fossil site and claim that these early pre-humans picked their teeth?

It's certain that no toothpick will ever last two million years, but this isn't the case with teeth. In fact, fossil teeth are the most durable⁴ remnants that anthropologists work with, and some of these ancient teeth display a curious set of grooves⁵. Although these might have been caused by tooth decay, a close examination of the marks seems to indicate that the grooves were worn by repeated toothpicking--probably to alleviate⁶ the pain of gum disease. Indeed, these fossil grooves match the toothpick grooves in the teeth of several modern aboriginal⁷ populations.

It's enough to warm every dentist's heart: The first tools weren't just for preparing food, hunting, or fighting. They might have been used for dental hygiene⁸ as well.  

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