Evolution of Blond Hair
Natural lighter hair colors occur most often in Europe and less frequently in other areas. In northern European populations, the occurrence of blond hair is very frequent. The hair color gene MC1R has at least seven variants in Europe giving the continent a wide range of hair and eye shades. Based on recent genetic research carried out at three Japanese universities, the date of the genetic mutation that resulted in blond hair in Europe has been isolated to about 11,000 years ago during the last ice age.
A typical explanation found in the scientific literature for the evolution of light hair is related to the requirement for vitamin D synthesis and northern Europe's seasonal deficiency of sunlight. Lighter skin is due to a low concentration in pigmentation, thus allowing more sunlight to trigger the production of vitamin D. In this way, high frequencies of light hair in northern latitudes are a result of the light skin adaptation to lower levels of sunlight, which reduces the prevalence of rickets caused by vitamin D deficiency. The darker pigmentation at higher latitudes in certain ethnic groups such as the Inuit is explained by a greater proportion of seafood in their diet. As seafood is high in vitamin D, vitamin D deficiency would not create a selective pressure for lighter pigmentation in that population.
An alternative hypothesis was presented by Canadian anthropologist Peter Frost, who claims blond hair evolved very quickly in a specific area at the end of the last ice age by means of sexual selection. According to Frost, the appearance of blond hair and blue eyes in some northern European women made them stand out from their rivals at a time of fierce competition for scarce males.
A theory propounded in The History and Geography of Human Genes (1994), says blond hair became predominant in Northern Europe beginning about 3,000 BC, in the area now known as Lithuania, among the recently arrived Proto-Indo-European settlers (according to the Kurgan hypothesis), and the trait spread quickly through sexual selection into Scandinavia. As above, the theory assumes that men found women with blond hair more attractive.
It is now hypothesized by researchers that blond hair evolved more than once. Published in May 2012 in Science, a study of people from the Solomon Islands in Melanesia found that an amino acid change in TYRP1 produced blonde hair.
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