: Dark hair results from high levels of eumelanin produced by melanocytes in the hair follicle bulb.
The color of human hair is determined by the concentration and ratio of two types of melanin: (brown-black) and pheomelanin (red-yellow). dark hair
Evolutionary biologists suggest that dark hair and skin evolved as an adaptation to intense solar radiation, particularly in equatorial regions. Biochemistry, Melanin - StatPearls - NCBI Bookshelf - NIH : Dark hair results from high levels of
: Pigment synthesis begins with the amino acid L-tyrosine , which is converted by the enzyme tyrosinase into dopaquinone. In the absence of high sulfur levels (cysteine), this precursor polymerizes into the dark eumelanin. Evolutionary Context particularly in equatorial regions. Biochemistry