Sure thing. Like most "things" in complex systems, a certain feature will have many functions and can evolve subtly to have yet another one. My eyebrows definit

Sure thing. Like most "things" in complex systems, a certain feature will have many functions and can evolve subtly to have yet another one. My eyebrows definitely help keep sweat out of my eyes, especially when the air is not very humid. The sweat hits the hair, wicks, and evaporates. Since human ancestors used to be covered in hair, the eyebrow is more of a patch of hair that was useful enough to be selected for when most of the rest of out hair was being selected out. I guess I consider the eye brow just the hair on the surface and maybe the skin/muscles to move it, not the whole bone structure underlying it.