Fun fact: Some northern European countries’ population is 80% blonde because their societies had males hunt for food which resulted in an increased amount of deaths and an imbalance in their population, with more females than males, sexual selection acted strongly on females.
Well, males overwhelmingly favored infantile traits that persisted past puberty in females which included light eyes and blonde hair, eventually leading to the feminization of males in those populations over time.
Fun fact # 2: Novel hair and eye colors common among Northwestern Europeans originate in the Siberian population but for some reason died out over time there! (The source for neolithic farmers’ variance in eye and hair colors may have been different)
Moreover, Kleisner et al. (2010) have found an apparent sex linkage between blue eyes and feminization of face shape. They initially wished to determine whether eye color influences perception of male dominance, using facial pictures of Czech men. The results showed that brown-eyed men were rated as more dominant than blue-eyed men. As a control, the authors repeated the experiment after altering the facial photos of the brown-eyed men to make them blue-eyed. These altered photos were still rated as more dominant.
Men’s preference for blonde hair may have gone through a similar runaway selection. As PT Senior Editor Carlin Flora has pointed out to me before, many young blond children cease to be blond and their hair turns dark long before they reach puberty (as Carlin’s did). So by preferring to mate with women with light blonde hair, men are often (maladaptively) attracted to prepubescent children. Their preference for women with large eyes may similarly be maladaptive. But men’s preference for women with neotenous features, and women’s possession of such features, may nonetheless have evolved via runaway selection.