The Puzzle of European Hair, Eye, and Skin Color

Abstract

Europeans, particularly northern and eastern Europeans, are unusually colored. Their hair can be not only black but also brown, flaxen, golden, or red, and their eyes not only brown but also blue, gray, hazel, or green. Their skin is pale, almost like an albino’s. This color scheme is more developed in women than in men and seems to have been selected for its visual properties, particularly brightness and novelty. Sexual selection is a likely cause. It favors eye-catching colors and, if strong enough, can produce a color polymorphism, i.e., whenever a visible feature becomes differently colored through mutation, the new color will spread through the population until it loses its novelty value and becomes as frequent as the original one. Such selection is consistent with 1) the many alleles for European hair and eye color; 2) the high ratio of nonsynonymous to synonymous variants; and 3) the relatively short time over which this color diversity developed. Sexual selection will target women if they outnumber men on the mate market. Among early modern humans, such imbalances resulted from 1) a low polygyny rate (because few men could provide for a second wife and her children) and 2) a high risk of early male death (because long hunting distances increased exposure to environmental hazards). Sexual selection of women was stronger at latitudes farther from the equator, where men were less polygynous and more at risk of death while hunting. It was strongest on continental steppe-tundra, where men provided for almost all family food needs by pursuing herds of reindeer and other herbivores over long distances. Although this type of environment is now fragmentary, it covered until 10,000 years ago a much larger territory—the same area where, today, hair and eyes are diversely colored and skin almost milk white.