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Black hair

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This article is about hair that is black in color. For information regarding hair that is the texture of unprocessed African hair, see Afro-textured hair.
File:Woman with shoulder-length black hair from behind 02.jpg
Female black hair from behind.

Black hair is the darkest and most common of all human hair colors globally, due to larger populations with this dominant trait. It is a dominant genetic trait, and it is found in people of all backgrounds and ethnicities. Black hair contains a large amount of eumelanin pigmentation, a type of melanin. This hair type contains a much more dense quantity of eumelanin in comparison to other hair colors, such as brown, blonde and red.[1] In English, various types of black hair are sometimes described as soft-black, raven black, or jet-black. The range of skin colors associated with black hair is vast, ranging from the palest of light skin tones to dark skin. Black-haired humans can have dark or light eyes.

Distribution

Black hair is known to be the most common in the continents of Asia and Africa.[2] Though this characteristic can also be seen in people of Southern Europe and France, it is a bit less common.[3] People of Celtic heritage in Ireland with such traits are sometimes known as the "Black Irish".[4] Black hair can come in a variety of textures, just as any hair color. Generally, the East Asian and Native American population has straight, black hair with a very thick cuticle layer[5] and South Asians have thick, wavy or curly hair,[6] while the general hair type seen in black African hair is thick, curly and dense with more hair growing from the head. The curly quality comes from the shape of the hair follicle, as straight hair grows from more circular hair follicles, and curly hair grows from more oval-like follicles.[7]

Hair is naturally reflective, so black hair is not completely dark in bright light. However, the darkest shade will not have a warm, neutral tone but a sheen which can seem almost blue, like the iridescence of a raven's wing; hence, sometimes referred to as raven-black.[citation needed] Jet black hair appears to have reflective silver color in bright sunlight.

Genetics

Native Americans, East Asian, Southeast Asian, Southwest Asian, Middle Eastern, Far East Russian, South Asian and Himalayan black-haired people have thicker hair due to the derived EDAR gene allele that is linked to thicker and potentially straighter hair in some parts of Asia, and shovel-shaped incisors. The derived EDAR gene arose approximately 30,000 years ago in China.[8][9][10] One study[which?] shows that Paleo-Indians had both variants of the EDAR gene, the derived G-allele and the ancestral A-allele. When they[who?] tested ancient DNA remains found in the Americas of the individuals named USR1, Anzick-1 and Laranjal-6700 the results showed that they carried the ancestral A-allele.[citation needed]

11,000-year-old remains of Cuncaicha and Lauricocha individuals from South America share alleles at the highest rate with present-day Amerindians, indicating that the derived G-allele increased in frequency in parallel with the ancestral A-allele.[11]

One of the most studied genes that produce brown hair is MC1R, which helps the body to produce the melanocortin protein. This protein in turn helps the body’s hair follicles to produce the type of melanin called eumelanin. To have black hair, one must have genetically inherited this gene from both of their parents, and brown hair is achieved when it is inherited from one parent. This gene is demographically common, as 90% of the total world population carries this gene. Black hair, along with brown hair, comes to turn grey in old age as the hair follicles can no longer produce the pigmentation, but the cause of this inability has yet to be determined.[12]

  • Chinese girl with black hair.
    Chinese girl with black hair.
  • A Circassian woman with black hair.
    A Circassian woman with black hair.
  • Amerindian with black hair with the derived G-allele
    Amerindian with black hair with the derived G-allele
  • Amerindian with black hair from North America with the ancestral A-allele
    Amerindian with black hair from North America with the ancestral A-allele
  • Amerindian with black hair from South America with the derived G-allele
    Amerindian with black hair from South America with the derived G-allele

See also

References

  1. ^ "Is hair color determined by genetics?: MedlinePlus Genetics". medlineplus.gov. Retrieved 2022-11-17.
  2. ^ Goodley, Alvin (2019-10-18). "4 Rarest Hair Colors in the World". Archived from the original on 2020-08-06.
  3. ^ The Distribution of Anthropological Traits in Europe, Bertil Lundman: The Races and Peoples of Europe (New York 1977)
  4. ^ Hornbeck, Shirley Elro (2000-01-01). This and that Genealogy Tips. Genealogical Publishing Com. ISBN 9780806350271.
  5. ^ Leerunyakul, Kanchana; Suchonwanit, Poonkiat (April 2020). "Asian Hair: A Review of Structures, Properties, and Distinctive Disorders". Clinical, Cosmetic and Investigational Dermatology. 13: 309–318. doi:10.2147/CCID.S247390. ISSN 1178-7015. PMC 7187942. PMID 32425573.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  6. ^ Mettrie, Roland (October 2007). "Shape Variability and Classification of Human Hair: A Worldwide Approach". Human Biology. 79 (3): 265–281. doi:10.1353/hub.2007.0045. PMID 18078200. S2CID 39460005.
  7. ^ "Why do people of African descent have a unique hair texture?". The Tech Interactive. 2021-12-23. Retrieved 2022-11-17.
  8. ^ "Native Americans and Asians carry a version of the EDAR gene that is linked to thicker hair shafts". 23 April 2018.
  9. ^ Kamberov, Yana G.; Wang, Sijia; Tan, Jingze; Gerbault, Pascale; Wark, Abigail; Tan, Longzhi; Yang, Yajun; Li, Shilin; Tang, Kun; Chen, Hua; Powell, Adam (2013-02-14). "Modeling recent human evolution in mice by expression of a selected EDAR variant". Cell. 152 (4): 691–702. doi:10.1016/j.cell.2013.01.016. ISSN 0092-8674. PMC 3575602. PMID 23415220.
  10. ^ Hlusko, Leslea J.; Carlson, Joshua P.; Chaplin, George; Elias, Scott A.; Hoffecker, John F.; Huffman, Michaela; Jablonski, Nina G.; Monson, Tesla A.; O’Rourke, Dennis H.; Pilloud, Marin A.; Scott, G. Richard (2018-05-08). "Environmental selection during the last ice age on the mother-to-infant transmission of vitamin D and fatty acids through breast milk". Proceedings of the National Academy of Sciences of the United States of America. 115 (19): E4426–E4432. Bibcode:2018PNAS..115E4426H. doi:10.1073/pnas.1711788115. ISSN 0027-8424. PMC 5948952. PMID 29686092.
  11. ^ Posth, C.; et al. (2018). "Reconstructing the Deep Population History of Central and South America". Cell. 175 (5): 1185–1197.e22. doi:10.1016/j.cell.2018.10.027. PMC 6327247. PMID 30415837.
  12. ^ "Is hair color determined by genetics?: MedlinePlus Genetics". medlineplus.gov. Retrieved 2022-11-17.

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