The distribution of red hair in Europe
This diagram shows the distribution of red hair in Europe. As you can see it is a patchy distribution, with high frequency in Ireland, Scotland and Wales with another large patch of high-frequency phenotypes in Russia.
Genomic data is likely to answer a few questions on this – like whether Red hair was more widely distributed throughout Europe in the past and nowadays it is only found on the periphery because of a later take-over of Europe by people that didn’t have red hair or alternatively, Red Hair might have originated in those places where is is found now and it never had a wide distribution.
The phenotypic manifestation of Red Hair occurs when an individual has two recessive alleles for the Melanocortin 1 Receptor. This is a kind of GPCR protein (a type of protein that is usually found embedded in the membrane of a cell and that often mediates the transfer of information from outside to inside the cell or vice versa). The gene for this protein is found on chromosome 16. In any case, if you have the recessive alleles, then you produce phaeomelanin (a yellow-ish reddish skin and hair pigment) and not Eumelanin (the brown-black pigment). If you have one recessive allele and one dominant allele, then you won’t have red hair and if you have two dominant alleles you won’t have red hair.
If you want to know more about human genetics, then maybe take a look at this book: “The Journey of Man: A Genetic Odyssey”
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