If facial variation is considered across anthropoid primates, a similar type of facial width-to-height sexual dimorphism (though more exaggerated) has been noted in the common chimpanzee and some other primates [17].
Sensitivity to facial width-to-height ratio appears to be part of an evolved mechanism designed to detect threats in the external environment.
The new finding in an Asian group suggests that the effect of facial width relative to height even other characteristics may cross cultural and ethnic boundaries.
Further examples include the heritability of facial width, which was reported to range from as low as 0.257 to 0.62914,21,30, nasal breadth heritability, varying between 0.352 and 0.63914,31,32, and cheek length heritability, ranging from 0.154 to 0.47521,33.
Also of note was the facial width-to-height ratio: Men tend to have "taller" faces than women, a result of testosterone release during adolescence in males.
For each of the four race and age groups, estimates of aggression were positively correlated with facial width-to-height ratio irrespective of rating own- or other-race faces.
It seems what the observer is instinctively looking for is a high facial width-to-height ratio (WHR), an indicator of high levels of testosterone.
Overall, the correlations between facial width-to-height ratio and ratings of aggression were stronger for adults than for children.
The hormone also increases their facial width-to-height ratio, a comparison of the distance between the cheekbones to the distance between the upper lip and brows.
Larger facial width-to-height ratios are generally associated with increased levels of testosterone in men, according to Michael Haselhuhn, an assistant professor of management at UC Riverside and a coauthor of the facial-width studies.
