In a range of non-human primate, bird and fish species, the intensity of red coloration in males is associated with social dominance, testosterone levels and mate selection. In humans too, skin redness is associated with health, but it is not known whether – as in non-human species – it is also associated with dominance and links to attractiveness have not been thoroughly investigated. Here we allow female participants to manipulate the CIELab a* value (red-green axis) of skin to maximize the perceived aggression, dominance and attractiveness of photographs of men’s faces, and make two findings. First, participants increased a* (increasing redness) to enhance each attribute, suggesting that facial redness is perceived as conveying similar information about a male’s qualities in humans as it does in non-human species. Second, there were significant differences between trial types: the highest levels of red were associated with aggression, an intermediate level with dominance, and the least with attractiveness. These differences may reflect a trade-off between the benefits of selecting a healthy, dominant partner and the negative consequences of aggression.
This may be as simple as a ruddy complexion being associated with good circulation and thus good health, indicating a fit mating prospect. Why red would be associated with aggression is less clear; although an extremely angry man may turn red, aggressive men don’t go around with red, angry faces all the time, so it’s hard to see how that could be selected for. Note also that men have higher hemoglobin levels than women, and this could have given rise to the stereotype of dark men and fair women. Men are supposed to be darker than women, and thus more red in a man’s skin could perhaps be interpreted as greater masculinity, hence dominance, aggression, etc.