Red hair

Red hair is a hair color shared by several species, among them humans, orangutans, domestic cats, cattle, and horses. It varies from a deep red through to bright copper.

Biochemistry and genetics of red hair

The biochemistry of red hair, discovered only in 1997, appears to be associated with the melanocortin-1 receptor while the red colour itself is produced by an iron compound. The recessive gene which gives people red hair, fair skin and freckles is certainly older than 50,000 years, and it could be as old as 100,000 years. All red heads are MC1R variants, and the prevalence of these alleles is highest in Celtic countries. MC1R is found on chromosome 16.

Related Topics:
1997 - Melanocortin-1 receptor - Freckles - Alleles - Celtic - Chromosome

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The genetics of red hair is now being uncovered, together with connections between red hair and melanoma and other skin disorders, and red hair and problems with anaesthesia.

Related Topics:
Genetics - Melanoma - Skin disorder - Anaesthesia

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There is evidence for genetic linkage of eye color with other hair colors such as brown hair, so it would not be surprising if red hair were linked with eye color inheritance. Some of those with copper hair have green eyes.

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Such a type of inheritance is close to what geneticists describe as an autosomal recessive mode of inheritance. This means, in practice, that both your parents may not have red hair, but both could be carriers for the gene for red hair. If this was the case, perhaps one in four of children might have red hair. If one of the parents has bright red hair, and therefore carries two of the changes (one on each of their chromosomes), and the other parent is a carrier, then perhaps 50% of the children might have red hair. It is this aspect of the inheritance of red hair that tends to lead to the various permutations of the milkman joke.

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