Dark | Hair

: 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

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

: Dark hair results from high levels of eumelanin produced by melanocytes in the hair follicle bulb. : Pigment synthesis begins with the amino acid

: Most individuals with dark hair possess two functional copies of the MC1Rcap M cap C 1 cap R : Dark hair results from high levels of

The Biology and Perception of Dark Hair Dark hair—encompassing shades from deep brown to jet black—is the most prevalent hair color globally, appearing in approximately 90% of the human population. This dominance is the result of specific genetic pathways, biochemical processes, and evolutionary adaptations that have favored the production of dense pigments. Genetic and Biochemical Foundations

gene, which signals melanocytes to produce eumelanin instead of pheomelanin.

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