We think of some types of eyebrows as attractive and some as unattractive, and many people spend as much time preening their eyebrows as they do applying makeup to their eyelashes or lips. Eyebrows are also one of our most expressive facial features. One of the clearest ways to tell somebody what you're thinking is to simply move your eyebrows up or down -- we all know what different eyebrow positions mean.

So, eyebrows obviously serve a lot of functions in our culture today -- beauty, nonverbal communication, distinctive appearance. But why are they there in the first place? As we evolved and lost most of the thick hair on our bodies, why did we keep that little bit over the eyes?