Human skin‐color sexual dimorphism: A test of the sexual selection hypothesis

Abstract

Applied to skin color, the sexual selection hypothesis proposes that male preference for light-skinned females explains the presence of light skin in areas of low solar radiation. According to this proposal, in areas of high solar radiation, natural selection for dark skin overrides the universal preference of males for light females. But in areas in which natural selection ceases to act, sexual selection becomes more important, and causes human populations to become light-skinned, and females to be lighter than males. The sexual selection hypothesis proposes that human sexual dimorphism of skin color should be positively correlated with distance from the equator. We tested the prediction that sexual dimorphism should increase with increasing latitude, using adult-only data sets derived from measurements with standard reflectance spectrophotometric devices. Our analysis failed to support the prediction of a positive correlation between increasing distance from the equator and increased sexual dimorphism. We found no evidence in support of the sexual selection hypothesis.

Effects of psychological stress on skin and hair pigmentation in Polish adolescents

“…In light of the acknowledged evolution concepts, it is rather difficult to provide a plausible explanation for this finding; however, there are populations where females are characterized by more pigmented skin, as well as populations characterized by a lack of sexual dimorphism in this feature (Madrigal and Kelly 2007). In contrast to the skin, no dimorphic differences were found in hair pigmentation processes.…”

“…In the majority of known populations, females are characterized by lighter pigmentation than males (e.g., Van den Berghe and Frost 1986;Frost 1988;Norton et al 2006;Madrigal and Kelly 2007), which most probably results from the necessity to synthesize a greater amount of vitamin D needed for the periods of pregnancy and lactation (e.g., Jablonski and Chaplin 2000;Parra 2007). This hypothesis is supported by a study of Mazess (1967), who states that female skin is the least pigmented during the reproductive period.…”

The role of sexually dimorphic skin colour and shape in attractiveness of male faces

“…Skin colour varies considerably between people from different regions of the globe but is sexually dimorphic within a specific region, with men having darker (lower L*) and redder (higher a*) skin compared to women (Jablonski & Chaplin, 2000;Russell, 2003;van den Berghe & Frost, 1986). Madrigal and Kelly (2007) analysing the prevalence of sexual dimorphic colour in different areas with different solar radiation, concluded that hormonal factors may be more reliable explanation of differences between sexes. Indeed, according to Hill et al (1995), discrimination of human sexes relies more on colour information than on face shape.…”

The other-species effect in human perceptions of sexual dimorphism using human and macaque faces

“…To address the effect of starting sex on judgements, we included both male and female stimuli. Because skin colour is sexually dimorphic in humans (e.g., Correnti, Testa-Bappenheim, & Granata, 1964; for review, see Madrigal & Kelly, 2007) and macaques (Waitt et al, 2003), we used shape-only transformations to create our stimuli. Next, ±50% of the differences in linear two-dimensional shape between the male and female averages are applied to a third target face (here, our composite faces of either species).…”