Genetics

The alleles Arg151Cys, Arg160Trp, Asp294His, and Arg142His on MC1R are shown to be recessives for the red hair phenotype.[26] The gene HCL2 (also called RHC oder RHA) on chromosome 4 may also be related to red hair.[27][28]

In species other than primates, red hair has different genetic origins and mechanisms.

Evolution

Origins

Red hair is the rarest natural hair color in humans. The non-tanning skin associated with red hair may have been advantageous in far-northern climates where sunlight is scarce. Studies Von Bodmer and Cavalli-Sforza (1976) hypothesized that lighter skin pigmentation prevents...