Why are we attracted to beauty?
That might sound like a silly question. Surely it’s self-evident. We are drawn to beauty because it’s… beautiful.
But there must be a deeper reason. A showy flower attracts a butterfly, but the lure only works because flowers are a rich source of sugary nectar. A peacock’s gaudy tail feathers attract a peahen, but only because the gaudiness advertises the male’s strength and ability to evade predators. Evolution favors individuals who are best able to detect and pursue valuable resources and mates: individuals with a keen eye for beauty.
What about humans? Well, many of us assume that beauty is only skin deep. That our outer appearance bears no relation to our inner qualities. But is this true?
Much of the scientific research on beauty is based on the opposite idea: the idea that beautiful people are healthier. We are attracted to people whose faces are average in shape, masculine or feminine (depending on gender), and with a clear complexion. Researchers have suggested that we prefer these traits not for their own sake but because they signal health.
A new study by psychologists at the University of Glasgow may be about to overturn this popular theory.
Ziyi Cai and her colleagues recruited almost 600 young female volunteers for a study of health and attractiveness. She took passport-style photographs of all the women, and then had these photographs rated for attractiveness by a group of other women and men. Cai also measured each face, so that she had objective scores for averageness, masculinity/femininity, and skin color. The volunteers answered questions about any recent infections and their perceived vulnerability to disease. They even provided saliva, which was analyzed for secretary immunoglobulin or SIgA — one of the antibodies that forms the first line of defense against microbial invasion.
Cai found that there were no relationships between any of the health measures and either the attractiveness ratings or the measurements of face shape and color.
Previous studies that looked at many of the same health and attractiveness variables did find a link between health and beauty, but rarely has such a large sample of volunteers been recruited: Cai’s study is powerful and so her results are perhaps more trustworthy than most.
Cai does note that her recruits were young women living in a developed country with access to free healthcare. It remains possible that a link between health and attractiveness might be detected among people who are at greater risk of contracting infectious diseases.
In the meantime, the real reason humans are attracted to beauty remains a mystery.
Cai, Z., Hahn, A. C., Zhang, W., Holzleitner, I. J., Lee, A. J., DeBruine, L. M., & Jones, B. C. (in press). No evidence that facial attractiveness, femininity, averageness, or coloration are cues to susceptibility to infectious illnesses in a university sample of young adult women. Evolution and Human Behavior. doi:10.1016/j.evolhumbehav.2018.10.002