In fact, research shows that when the left side of your face and the right side are well matched, people will find you attractive. Studies have also shown that babies prefer staring at the photos of symmetric faces than asymmetric ones. Along with symmetry, some evolutionary facial features are also key to the biology of beauty. Men prefer women with a small jaw, a small nose, large eyes and defined cheekbones. Among other things, females are looking for men with a strong jaw.
"The power of looks in social life has never changed from our evolutionary ancestors. If you look at cross cultures and traditional societies, you see the same sort of patterns. Attractive women get rewarded with more attractive husbands, husbands who are better providers," Thornhill said. Perhaps that explains Angelina Jolie and Brad Pitt.
These days, of course, many people try to "fool" Mother Nature with a little help from modern medicine.
"The only way you can change the symmetry of your face is through plastic surgery. You can trick the brains of others," Thornhill said.