Eye color predicts but does not directly influence perceived dominance in men
Karel Kleisner et al. (2010)
Personality and Individual Differences
In this study we found no effect of eye color on perceived dominance in women. On the contrary, we found a statistically significant association between the eye color and perceived dominance in men: brown-eyed men were perceived as more dominant. Furthermore, we show that iris color does not represent the trait that significantly influences perception of dominance in males. Hence, there must be some other facial characteristics responsible for the higher perceived dominance in brown-eyed males. It is evident, however, that the features standing for higher perceived dominance in males are correlated with presence of brown eyes; or alternatively, the features connected with higher perceived submissiveness in males with the blue eyes.
The question arises: why are brown-eyed males rated as more dominant than blue-eyed? Some facial features such as square jaws, thick eyebrows and broad cheekbones are linked with higher perceived dominance; facial submissiveness, on the other hand, is characterized by a round face with large eyes, smallish nose, and high eyebrows (Berry, 1990; Berry & Mcarthur, 1986; Cunningham, Barbee, & Pike, 1990; Mazur, Halpern, & Udry, 1994; Mueller & Mazur, 1997; Thornhill & Gangestad, 1994). The morphological differences between blue-eyed and brown-eyed males were visualized by deformation of thin-plate splines (Fig. 3). In contrast with blue-eyed males, brown-eyed males have statistically broader and rather massive chins, broader (laterally prolonged) mouths, larger noses, and eyes that are closer together with larger eyebrows. In contrast, blue-eyed males show smaller and sharper chins, mouths that are laterally narrower, noses smaller, and a greater span between the eyes. Especially the broader massive chin, bigger nose, and larger eyebrows of brown-eyed males may explain their higher perceived dominance.
Fig. 3. (a and b): Visualizations of shape regression on eye color in males by thin-plate spline deformation grids illustrating differences in facial shape between blue-eyed (a) and brown-eyed (b) males; the links connecting the landmarks are drawn for better imaging of differences in the shape of face. (c and d): Composite images of 20 photographs of each group unwarped to fixed landmark configuration predicted by shape regression of blue-eyed (c) and brown-eyed (d) male faces. The predictions are magnified three times for better readability. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
However, it is not easy to explain how iris color, which is determined mostly by one or a few genes, can correlate with physiognomic dominance/submissiveness, which is determined by a combination of several independent morphological traits. Theoretically, the allele for brown eyes should "move" from "submissive physiognomy genotype" to "dominant physiognomy genotype" and back again from generation to generation due to genetic recombination and segregation.
In principle, there are three possible explanations for the higher perceived dominance of brown-eyed males, the pleiotropy hypothesis, genetic linkage hypothesis and social feedback hypothesis. The pleiotropy hypothesis presumes that the genes for iris color (such as HERC2 or OCA2) also influence other morphological traits associated with perceived dominance due to its pleiotropy effect. One can speculate, for instance, that the gene influences the production or metabolism of common precursors of adrenaline and melanin, e.g. DOPA or tyrosine.
The genetic linkage hypothesis presumes that the genes influencing iris color are in genetic linkage with genes influencing morphological traits associated with perceived dominance, for example the gene influencing the production of testosterone. If this is so, strong linkage disequilibrium between these loci should exist in the current Czech population. Repeating this study in other populations with polymorphism in eye color can test this hypothesis.
The social feedback hypothesis is based on the presumption that blue and brown-eyed subjects are treated differently within their social surroundings, e.g. by their parents and peers. Young children usually have blue eyes, while definitive iris color develops during the first years of life (Bito, Matheny, Cruickshanks, Nondahl, & Carino, 1997). It is possible that subjects with blue eyes are treated as a small child for a longer period than brown-eyed children. Such early social experience may have been literally "inscribed" into their faces, preserved until adulthood, and finally bring on the perception of higher submissiveness. Rosenberg and Kagan (1987, 1989) investigated the association between eye color and behavioral inhibition, revealing that children with blue eyes are more inhibited. Coplan et al. (1998) found a significant interaction between eye color and social wariness within preschoolers. Blue-eyed males were rated as more socially wary, i.e. being more temperamentally inhibited, displaying more reticent behavior and having more internalizing problems, than males with brown eyes, though there were no differences between blue- and brown-eyed females (Coplan et al., 1998). To test the third hypothesis, it would be necessary to perform a longitudinal study on preschool children to search whether the differences in perceived dominance (and social wariness) develops only after the transformation of iris color from blue to brown.