The resultant visible hue depends on various factors, but always has some sort of 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 generally very rare in adulthood. Naturally-occurring blond hair is primarily found in populations of northern European descent and is believed to 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.