Chinese people predominantly have black hair because the genes responsible for black hair are dominant and prevalent in East Asian populations. Unlike populations in Northern Europe, a genetic mutation leading to blonde or red hair didn't become widespread in China.
Here's a more detailed explanation:
-
Dominance of Black Hair Genes: Black hair color is determined by the presence of a specific gene variant. This variant is dominant, meaning that an individual only needs one copy of this gene to express black hair.
-
Lack of Widespread Alternative Genes: In populations where lighter hair colors like blonde or red are common, specific genetic mutations have occurred and become more prevalent. These mutations, often recessive, alter the production of melanin (the pigment responsible for hair color). These mutations haven't become widespread in Chinese populations.
-
Melanin Production: Hair color is determined by the amount and type of melanin produced in the hair follicles. Eumelanin is responsible for dark brown and black pigments, while pheomelanin produces red and yellow pigments. Chinese people typically have a high concentration of eumelanin, resulting in black hair.
-
Genetic Variation: While black hair is most common, genetic variation exists within China. Some individuals may have slightly lighter shades of brown or, rarely, traces of red pigments, but black remains the dominant hair color. The reference mentions a Mongolian influence potentially leading to blonde or red hair. This reflects genetic admixture in specific regions.
In summary, the prevalence of black hair among Chinese people is due to the dominance of black hair genes and the relative absence of genetic mutations that lead to lighter hair colors.
