See that crud near the roots of this long-dead bipedal primate's teeth? It's tartar. Two million year old tartar. This is what happens when you don't brush, people -- and don't tell me it's just because the invention of toothbrushes was 70,000 generations in the future.
This tartar in particular is the mineralized remains of the last few meals of an Australopithecus sediba, which may very well be the ancestor of all humans and the "missing link" between the Austrilopithecus genus and our own Homo genus. (Humans, or H. sapiens, are part of the Homo genus.)
Scientists hope to scrape that tartar off and figure out exactly what "cave men" were eating 2 million years ago, which, according to some, has relevance to what we should eat today.
But first they have to get the tartar off. One way to do it is dental tools, but then you run the risk of damaging the invaluable fossil itself. Another solution is a kind of super mouthwash, a solution including 4 percent hydrochloric acid, which has the (unfortunate from a scientific perspective) effect of whitening prehistoric teeth.
Once the tartar has been removed from the fossil, scientists go at it with microscopes, which allow them to examine the tiny, mineralized remains of the creature's last meals. Telltale signs of past meals include phytoliths, which are tiny minerals produced by plants. This can reveal exactly which plants were consumed. Other bits of grit can provide evidence of a diet of animal flesh, even seafood.