• Ethnic differences in hair fiber and hair follicles
• Ethnic differences in hair fiber and hair follicles references

Ethnic differences in hair fiber and hair follicles

Each individual is unique and hair production rate, size, and shape differs for everyone, but in general there are some differences in the nature of hair fiber for people of different ethnic backgrounds.

Asian hair is on average the thickest and most coarse hair compared to Caucasian and African American hair. It is almost always straight and circular in cross section. The density of Asian hair on the scalp (follicles per unit area of skin) is less than that typically observed in Caucasians. The density of hair follicles in African Americans is also somewhat lower than for Caucasians on average. At the lowest end of the spectrum the density of Asian may be just 90,000 scalp follicles and rarely gets above 120,000 scalp follicles.

Caucasian hair can be quite variable in its presentation with straight, wavy or curly hair. The fiber can be circular or oval in cross section and is on average thinner than Asian hair. Hair follicle density varies and density can be approximately related to hair color. Red haired people have the least dense scalp hair growth of Caucasians, blonds the most dense and brown haired people somewhere in the middle. Denstiy can range from 100,000-150,000 scalp hair follicles

African American hair is frequently tightly coiled, or spiral hair. In cross section it is elliptical or almost flat and ribbon-like in some cases. This means that there is more strength and rigidity to the fiber across the area of greatest cross section but the hair is much more pliable across the narrow section. This results in the curls of hair all naturally flexing and coiling along the ribbon while there is little or no coiling from side to side.

Different hair fiber types are produced by different hair follicles. Large, straight hair follicles with a circular cross section produce thick straight hair. Curly, flat hair follicles make curly elliptical or ribbon shaped cross section hair. Many African Americans have very curly, flattened hair follicles in their skin that produce highly coiled hair. Some research suggests that the hair follicles are actually spiral/spring shaped if you were able to look down the length of these hair follicles.

The shape of the hair follicle acts as a mold for the creation of the hair fiber. Deep in the hair follicle, where cells are added to the fiber at the root, the hair is soft and pliable. The cells of the fiber take the shape of the surrounding hair follicle sheath. As the cells are squashed together and keratinized, the chemical bonds form and hold the hair fiber into the shape of the hair follicle. Hence curly hair follicles make curly hair fibers. Don't ask what makes curly hair follicles because we don't know! There might also be racial differences in the chemical composition of the fiber. Some research studies suggest African American hair has a greater amount of low sulfur protein compared to high sulfur protein than observed in Asian or Caucasian individuals. However, other more recent studies have not found a significant difference in the sulfur content of hair fiber from people of different ethnicities.

People with very coiled hair often claim it seems to weather more rapidly with cuticle flaking and deterioration in hair quality. In part this is probably due to the coling putting stress on the hair fiber cuticle. The outer side of a coiled hair has cuticle that is stretched thin and the scales are relatively exposed and easy to catch and damage as when bushing for example. In contrast, the cuticle in the inner side of a coiled hair is relatively thick and scrunched together. Because the hair on the outer side of the coil is so thin and stretched it takes less physical or chemcial action to flake and damage the cuticle exposing the softer cortex of the hair underneath.

If anything, African American hair follicles produce more oils and sebum than follicles in other ethnic groups, but the oils are not evenly distributed along the length of the hair fiber because of its coiled shape. As a result, the hair fiber is typically very dry Consequently, African Americans are more likely to need hair oils to supplement their natural oil production and help keep the hair fiber flexible. In addition, tight spiral hair is difficult to brush and comb. Using oils helps reduce the friction and static from combing and make the hair more manageable. African Americans often find they need to use specially formulated oils and shampoos. African American hair responds differently than Caucasian and Asian hair and preferred grooming products contain humectants and mild cleansing agents while avoiding harsh plant oils or harsh detergents such as sodium lauryl sulfate.

Ethnic differences in hair fiber and hair follicles references

• Lee HJ, Ha SJ, Lee JH, Kim JW, Kim HO, Whiting DA. Hair counts from scalp biopsy specimens in Asians. J Am Acad Dermatol. 2002 Feb;46(2):218-21.
• Loussouarn G. African hair growth parameters. Br J Dermatol. 2001 Aug;145(2):294-7.
• Khumalo NP, Doe PT, Dawber RP, Ferguson DJ. What is normal black African hair? A light and scanning electron-microscopic study. J Am Acad Dermatol. 2000 Nov;43(5 Pt 1):814-20.
• Sperling LC. Hair density in African Americans. Arch Dermatol. 1999 Jun;135(6):656-8.
• Lucky AW, Biro FM, Daniels SR, Cedars MI, Khoury PR, Morrison JA. The prevalence of upper lip hair in black and white girls during puberty: a new standard. J Pediatr. 2001 Jan;138(1):134-6.
• Pavlov IV. [Study of transverse sections and pigment granules of the hair of persons of various nationalities]. Sud Med Ekspert. 1989 Jan-Mar;32(1):35-6.
• Nikolaeva SS, Dubinskaia VA. [Physico-chemical properties of head hair of people of European and Negroid races]. Sud Med Ekspert. 1989 Apr-Jun;32(2):17-20.
• Dekio S, Jidoi J. Hair low-sulfur protein composition does not differ electrophoretically among different races. J Dermatol. 1988 Oct;15(5):393-6.
• Lindelof B, Forslind B, Hedblad MA, Kaveus U. Human hair form. Morphology revealed by light and scanning electron microscopy and computer aided three-dimensional reconstruction. Arch Dermatol 1988 Sep;124(9):1359-63
• Eckes LK. [Body hair: an atavistic relic]? Hautarzt. 1987 Mar;38(3):125-30.
• Eriksson AW, Frants RR, Kirjaranta M, Kajanoja P. Studies on hair pigmentation and blood groups in the Bashkirs. Ann Acad Sci Fenn A. 1986;175:25-32.
• Eckes LK. [Ethnic variations of scalp hair]. Hautarzt. 1985 Jul;36(7):381-5.
• Das-Chaudhuri AB, Chopra VP. Variation in hair histological variables: medulla and diameter. Hum Hered. 1984;34(4):217-21.
• Bhatia RY, Rao KV, Rao NP. Site variations in scalp hair morphology in pre-school children. Indian J Med Res. 1980 Jun;71:890-2.
• Pandey AK, Saran S, Shukla R. Medullary structure of head hair in Gurkha: a Mongoloid population of Dehra Dun, India. Anthropol Anz. 1980 Aug;38(3):206-11.
• Lee LD, Ludwig K, Baden HP. Matrix proteins of human hair as a tool for identification of individuals. Forensic Sci. 1978 Mar-Apr;11(2):115-21.
• Hrdy DB, Baden HP, Lee LD, Kubilus J, Ludwig KW. Frequency of an electrophoretic variant of hair alpha keratin in human populations. Am J Hum Genet. 1977 Jan;29(1):98-100.
• Rook A. Hair II Racial and other genetic variations in hair form. Br J Dermatol. 1975 May;92(5):599-600.
• Das BM. A study of cross sections of head hair from some caucasoid and mongoloid populations of Assam, India. Z Morphol Anthropol. 1974 Feb;65(3):324-8.
• Kerley ER, Rosen SI. The identification of Polynesian head hair. J Forensic Sci. 1973 Oct;18(4):351-5.
• Hrdy D. Quantitative hair form variation in seven populations. Am J Phys Anthropol. 1973 Jul;39(1):7-17.
• Hrdy D, Baden HP. Biochemical variation of hair keratins in man and non-human primates. Am J Phys Anthropol. 1973 Jul;39(1):19-24.
• Setty LR. Hair patterns of the external surface of the nose of American Negro and white males. J Natl Med Assoc. 1973 May;65(3):214-5.
• Setty LR. The distribution of posterior cervical hair in white and Negro males. J Natl Med Assoc. 1972 May;64(3):239-41.
• Stybalkowski M. [Microscopy studies of cross-sections of head hair of Sevettijarvi-Skolt Laplanders]. Anthropol Anz. 1972 Jun;33(3):219-32.
• Gold RJ, Scriver CG. The amino acid composition of hair from different racial origins. Clin Chim Acta. 1971 Jul;33(2):465-6.
• Setty LR. Hair patterns of the face of white and negro males. J Natl Med Assoc. 1971 Mar;63(2):128-31.
• Setty LR. Hair patterns of scalp of white and Negro males. Am J Phys Anthropol. 1970 Jul;33(1):49-55.
• Setty LR. Scrotal hair patterns of Whites and Negroes. J Natl Med Assoc. 1970 Mar;62(2):156-8.
• Wassermann HP. Ethnic differences in natural melanoproteins. Dermatologica. 1970;141(1):44-8.
• Setty LR. Penile hair patterns of whites and negroes. J Natl Med Assoc. 1969 Jan;61(1):67-9.
• Setty LR. The distribution of hair of the lower limb in white and Negro males. Am J Phys Anthropol. 1968 Jul;29(1):51-5.
• Bhalla V, Kaul SS. Occipital hair whorl as a racial criterion: a critical assessment. Am J Phys Anthropol. 1968 Jul;29(1):99-101.
• Shimode T. Morphological studies of head hair in Ainu. Sapporo Igaku Zasshi. 1968 Oct;34(4):181-215.
• Yonemoto Y. Studies on measurements of the scalp tissue of the Japanese adult (I). Okajimas Folia Anat Jpn. 1968 Sep;45(2):83-97.
• Banerjee AR. On variation of human head hair: hair form and medullation. Z Morphol Anthropol. 1965 Sep;57(1):56-69.
• Setty LR. Variations of the hair patterns of the chest of white males. J Natl Med Assoc. 1965 May;57(3):211-4.