The stuff that clings to teeth can tell an interesting story.
On Wednesday, scientists revealed new insights gleaned from dental plaque stuck on the teeth of five Neanderthals from Europe. From a few teeth, scientists learned how Neanderthals used natural medicines and how their diets varied by region. They also learned that modern humans and Neanderthals were swapping spit long ago.
Given time—and negligence—dental plaque will harden into a substance called calculus, which is comp