Our ancient ancestors had a prominent ridge of bone above their eyes, but scientists are not sure of its purpose—or why it disappeared. Some have suggested the bone provided filler between the brain and eyes or reduced strain on the face during eating.

What is the purpose of a forehead?

You can also call your forehead your "brow." It's important for communication, since the forehead helps people express basic emotions — muscles in your forehead control the movement of your eyebrows, which help you express concern and anger, among other feelings.

Why do humans have big foreheads?

Kwan believes that due to climate and technological advancements, humans will have larger foreheads to accommodate a larger brain. With the ability to control the human genome, genetic engineering will become the norm and he writes, "the fate of the human face will be increasingly determined by human tastes."