The lower melanin concentration in skin confers the advantage that a sufficient concentration of important Vitamin D can be produced under low light conditions.
However, when UV-radiation is strong (as in regions close to the equator) the lower concentration of melanin leads to several medical disadvantages, such as a higher risk of skin cancer.
Abd ar-Rahman I also had red hair, his mother being a Christian Berber slave.
However, a How Stuff Works article says that the foundation was funded by hair-dye maker Procter & Gamble, and that other experts had dismissed the research as either lacking in evidence or simply bogus.
making it the most red-haired country in the world.
According to Britain's DNA, 34.7% of the Irish population carry the allele for red hair, although this doesn't directly translate proportionally into births of red-haired children. Jim Wilson of Britain's DNA study used a sample of 2,343 people, and found red hair occurrence of 6% in Scotland, with 35% overall carrying the allele and Edinburgh having the highest proportion at 40%. The Queen of Morocco, Lalla Salma wife of king Mohammed VI, has red hair.
It is characterized by high levels of the reddish pigment pheomelanin and relatively low levels of the dark pigment eumelanin.
It is associated with fair skin color, lighter eye colors (gray, blue, green, and hazel), freckles, and sensitivity to ultraviolet light.