White males with high levels of carotenoids — yellow and red pigments — in their skin appear healthier and more attractive to females; but this skin tone does not necessarily signal good health, according to a new study published in the journal Behavioral Ecology.
“Carotenoids are known to be responsible for the striking mating displays in many animal species,” said Yong Zhi Foo, Ph.D., author and postgraduate animal biology student at the University of Western Australia.
“Our study is one of the first to causally demonstrate that carotenoids can affect attractiveness in humans as well. It also reaffirms the results of previous studies showing that what we eat can affect how we look.”
Carotenoid-based coloration plays an important role in sexual selection for many different species. Previous research has found that in various species such as birds, fish, and reptiles, females are more attracted to their colorful male counterparts.
Researchers have argued that carotenoid-based coloration is an honest signal of health and is associated with antioxidant action. One proposal is that people are attracted to signs of health for reproduction purposes, and those who display signs of health have a greater chance of survival, greater fertility, and providing genes that promote good health in offspring.
In the new study, the researchers investigated whether there is any correlation between carotenoids and actual health. The research involved 43 heterosexual Caucasian men with a mean age of 21 years and a placebo group of an additional 20 male participants.
Photographs were taken of participants at the beginning and end of the study in order to document any changes in skin color. Participants were tested on their health, which included their level of oxidative stress, immune function, and semen quality.
Once their health was reviewed, the participants were given a 12-week supplementation of beta-carotene, and the placebo group was given “dummy pills.” Participants returned after the 12 week period to repeat the health tests.
Sixty-six heterosexual Caucasian females with a mean age of 33 were recruited online to rate the attractiveness of the pre- and post-supplementation faces of each male participant. The mens’ before/after faces were presented side by side on a computer screen.
The findings show that the beta-carotene supplements increased overall yellowness and redness but not lightness. Post supplement faces were 50 percent more likely to be chosen as attractive as well as healthier looking compared to the pre-photographs or the placebo group.
Thus beta-carotene supplementation significantly enhanced participants’ attractiveness and appearance of health. Beta-carotene treatment did not, however, significantly affect any health functions.
This study provides the first experimental evidence of beta-carotene’s effect on attractiveness and health. The findings suggest that carotenoid-based skin color may be sexually attractive to humans, but there is no evidence to suggest that this is an honest signal of health.
Source: Oxford University Press