In a new study, researchers say they now know why we have eyebrows! Yay! Previous theories have proposed that early man needed the eyebrows for protection, or to aid them with chewing tougher grub. But scientists now believe that eyebrows were needed to express more subtle emotions than early man needed to convey. That non-verbal communication was essential to give early humans the chance to get to know, at a glance, what others are thinking.