I’ve always been fascinated by symmetry in nature. From the radial symmetry of a snowflake or a starfish, to the bilateral symmetry of a crab shell or a human body, nature’s ability for complementation is astounding. But the fact that symmetry is so widespread is no coincidence. Whether it’s a bird or a human, symmetry means good genes, and that means attraction.
Humans, like most animals, exhibit mirror symmetry, meaning we are roughly the same on both sides. This is something we subconsciously find appealing in our mates. For instance, men are more attracted to women with symmetrical features. In a study at the University of New Mexico in Albuquerque, females with symmetrical faces were not only more attractive to their male peers than females with asymmetrical faces, they also had a higher number of previous sexual partners and tended to lose their virginity at an earlier age.
The situation is true for a man’s attractiveness to a woman as well. Though women are more apt to look for things like status and dominance, which 
may be stronger indicators of fitness than symmetry, we still value matching components. Studies have found that women achieve greater sexual satisfaction with partners who are symmetrical, and find symmetrical dancers more attractive than asymmetrical ones. This indicates body, not just facial symmetry, is an important component of attraction.
Symmetry’s role in mate selection is based on the hypothesis that it can give clues to underlying genetic fitness. Asymmetry can show flaws in the genetic code or a predisposition to disease—someone you don’t want your genes commingling with. Because of the ability of symmetry to advertise someone’s health, it is an outward clue to help us select a good mate.
Yet it stands to question whether we find symmetrical faces and bodies more attractive because they’re healthier, or because that’s what we’re used to. Look at the cover of any fashion magazine and it’s easy to conclude that most models’ faces are almost mirror images of each other, with very little skewing. Does our idea of attractiveness have more to do with nature, or the norm?
Evidence shows that symmetry is an attractive trait within and across cultures, indicating it’s important regardless of cultural norms. A study comparing the preferences of people in the United Kingdom with the Hadza, a hunter-gatherer society of Tanzania, found that symmetry was more attractive than asymmetry across both cultures. In fact, symmetry was an even bigger cue of attractiveness in the Hadza than in the Brits, suggesting that ecological pressures may be a selective pressure for this society, forcing it to find outward signs of genetic quality. Symmetry is one of these signs. Furthermore, men with higher standing (the good hunters) placed greater value on symmetry in the female face than men of lower standing; that is, men of high quality were more discriminating, and one way in which they discriminated was by facial symmetry.
