When you squint your eyes, your upper and lower eyelashes come together to form an interweaving mesh of hairs. This allows you to still see clearly, but it protects your eyes from any large particles of sand, dirt or grit that might fly into your eye. Likewise, your eyebrows serve as an important barrier to any liquid, like rain, sea spray or sweat, that might roll down your forehead and into your eyes. Of course, eyebrows do a lot more than just protect your eyes. Humans use them to express their emotional state.
Furrowed brows make for a look of thoughtfulness.
Raised brows give a look of surprise. While lowered brows make a person appear angry or threatening. In fact, romance writers still suppose that batting an eyelash or two expresses its own special meaning for pretty girls. Just how this is supposed to work is still an open question for science. All stories by Andrew Adamson and Gloria Chang .