While "ideal" beauty continues to change, one-thing remains constant—facial symmetry is key to perceived beauty. “Even though the ideals of beauty have changed over time, perfect proportion is the underlying theme,” says Montreal plastic surgeon Arthur Swift, MD.
Yup, there's no denying it: Perfect facial symmetry is an important factor when it comes to physical beauty. Science has attested on numerous occasions that our beauty increases when facial symmetry is increased, and decreases when symmetry is decreased, in individual faces. Why is this? Evolution. Research supports the claim that facial symmetry indicates a better coping system for environmental factors, which implies worthiness for mating. Basically, though we might not realize it off the bat, we're more attracted to faces that are symmetrical. And if you look at the laundry list of gorgeous celebrities boasting perfect symmetry, you can see we have idealized facial proportions for quite some time.
With her perfectly balanced oval-shaped face and slim nose that points upward, Grace Kelly was considered the epitome of natural beauty. Click through the rest of this gallery to see which stars' faces throughout history, and into today, have determined what we find beautiful.