Blond or fair hair is a hair color characterized by low levels of the dark pigment eumelanin. The resultant visible hue depends on various factors, but always has some yellowish color. The color can be from the very pale blond (caused by a patchy, scarce distribution of pigment) to reddish "strawberry" blond or golden-brownish ("sandy") blond colors (the latter with more eumelanin). Because hair color tends to darken with age, natural blond hair is significantly less common in adulthood. Naturally-occurring blond hair is primarily found in populations of northern European descent and may have evolved to enable more efficient synthesis of vitamin D, due to northern Europe's lower levels of sunlight. Blond hair has also developed in other populations, although it is usually not as common, and can be found among natives of the Solomon Islands, Vanuatu, and Fiji, among the Berbers of North Africa, and among some Asians. In Western culture, blond hair has long been associated with female beauty. Aphrodite, the Greek goddess of love and beauty, was described as having blond hair. In ancient Greece and Rome, blond hair was frequently associated with prostitutes, who dyed their hair using saffron dyes in order to attract customers. The Greeks stereotyped Thracians and slaves as blond and the Romans associated blondness with the Celts and the Germans to the north. In western Europe during the Middle Ages, long, blond hair was idealized as the paragon of female beauty. The Norse goddess Sif and the medieval heroine Iseult were both significantly portrayed as blond and, in medieval artwork, Eve, Mary Magdalene, and the Virgin Mary are often shown with blond hair. In contemporary western culture, blond women are often negatively stereotyped as sexually attractive, but unintelligent. In the late nineteenth and early twentieth century, scientific racists categorized blond hair and blue eyes as characteristics of the supreme Nordic race.