Quantifying variation in human scalp hair fiber shape and pigmentation

Lasisi, Tina; Ito, Shosuke; Wakamatsu, Kazumasa; Shaw, Colin N.

doi:10.1002/ajpa.22971

Cited by 26 publications

(41 citation statements)

References 58 publications

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“…Quantitative studies on the type and amount of melanin in hairs relating to the ranges of hair color expression offer an effective avenue to study hair color and composition at a chemical level (Ito & Jimbow, ). Chemical analysis of melanin in hair by High Performance Liquid Chromatography (HPLC; Ito & Wakamatsu, ; Lasisi, Ito, Wakamatsu, & Shaw, ) has revealed a relationship between hair color and the quantity of melanin within hair. The ratio of pheomelanin to eumelanin can be determined chemically, though it may not be visually discernible.…”

Section: Hair Morphology Pigmentation and Developmentmentioning

confidence: 99%

“…Diversity in human scalp hair morphology can be attributed to the variation in hair form across a person's scalp, changes that develop over time because of age or health, differences that exist among individuals, and those caused by a person's genetic background. Empirical research quantifying hair characteristics in different populations has long been pursued in anthropology (Banerjee, 1965;Hausman, 1925aHausman, , 1925bHausman, , 1928Hausman, , 1934Hrdy, 1973;Lasisi et al, 2016;Trotter, 1930;Wynkoop, 1929), forensic science (Bisbing & Wolner, 1984;Gaudette, 1978;Gaudette & Keeping, 1974;Strauss, 1983;Wickenheiser & Hepworth, 1990), and continues to be done in cosmetic research (Bernard, 2003;De La Mettrie et al, 2007;Thibaut et al, 2007). A common, up-to-date lexicon that is current and easily transferable among disciplines would facilitate the development of innovative and transdisciplinary methods to analyze hair.…”

Section: Use Of Microscopy In Hair Characterization and Identificationmentioning

confidence: 99%

See 1 more Smart Citation

The biology of human hair: A multidisciplinary review

Koch

Tridico²,

Bernard

et al. 2019

American J Hum Biol

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In the last century, human scalp hair morphology has been studied from multiple, and sometimes mutually exclusive, perspectives by anthropologists, biologists, geneticists, forensic scientists, and cosmetic scientists. Here, we review and synthesize historical and current research on hair to better understand the scientific basis and biological implications of hair microstructure and morphology. We revisit the origins of existing nomenclature regarding hair morphology and classifications, discuss the currently recognized limitations to hair analysis within the varied scientific disciplines studying hair, point out aspects of hair biology that remain unknown, and the great potential for integrating these diverse perspectives and expertise in future scientific investigations, while highlighting the benefits of combining nondestructive microscopical analysis with chemical and genomic analyses for explicating hair biology. Further, we propose consensus terminology for root growth stages through descriptions and images that will aid in the morphological and microscopical analysis of human scalp hair, thereby reducing confusion and the promulgation of inaccurate information that is presently in the literature.

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Section: Hair Morphology Pigmentation and Developmentmentioning

confidence: 99%

Section: Use Of Microscopy In Hair Characterization and Identificationmentioning

confidence: 99%

The biology of human hair: A multidisciplinary review

Koch

Tridico²,

Bernard

et al. 2019

American J Hum Biol

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“…Though the classification is complex, [2,7] certain combinations of these properties tend to be associated with hairs of specific ethnicity [Asian: straight, black, round cross section; European: black-blonde, straight-wavy, slightly elliptical; African: curly, black, strongly elliptical]. [8] Hairs grow from follicles, which extend from the subcutis through dermis and epidermis to the surface of the skin. During its growth, a hair develops its complex morphology on all structural levels.…”

Section: Introductionmentioning

confidence: 99%

Why is hair curly?—Deductions from the structure and the biomechanics of the mature hair shaft

Wortmann

Sripho

2019

Experimental Dermatology

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The final shape of a head hair is predetermined through a variety of factors during its formation in the follicle. These are genetic pathways, specific growth factors, cell differentiation and segregation, etc, with spatial as well as chronological dynamics. The cortex of hair consists of two major cell groups. These are characterized by parallel (para‐type) or roughly helical arrangements (ortho‐type) of the intermediate filaments (IF). There are also cell‐specific differences in the disulphide content, that is, of the cross‐link density of the IF‐associated matrix proteins. Given the current state of the academic discussion, we consider it as timely to support and broaden the view that, the structural differences of the cell types together with their lateral segregation are the main driving factor of curl formation. The mechanical effects, which derive thereof, are triggered in the transition zone of the follicle, that is, upon formation of the mature hair shaft. Furthermore, an irregular, “flat” cross section of the hair shaft is shown to be a synergistic but not determining factor of curl formation. The degree of cell type segregation along the mature hair shaft together with dynamic changes of the location of the plane of segregation, namely in a non‐circular cross section can account for very complex curl patterns. Against the background of these views, we argue that contributions to hair curl are implausible, if they relate to physical mechanisms which are active below the transition zone from the living to the mature (dead) hair.

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“…More recently, Fratto & Davis (2011) found that melanistic (black fur) fox squirrels (Sciurus niger) had significantly thinner body hairs and thicker tail hairs than the other fur colours, presumably to offset increased heat absorption due to the darker coloured fur. Human hair also exhibits a wide range of physical characteristics including fibre shape, curvature, kink, and colour (Restano et al 2001, Lasisi et al 2016, De La Mettrie et al 2019. Within humans there is also variation in the cross-sectional shape of hair follicles, both in terms of width and shape (round vs. oval).…”

Section: Introductionmentioning

confidence: 99%

“…Within humans there is also variation in the cross-sectional shape of hair follicles, both in terms of width and shape (round vs. oval). Specifically, Asian populations have thicker crosssectional area (Lasisi et al 2016) and straighter hair (Fujimoto et al 2008), whereas humans of African descent have a more elliptical cross-sectional shape and greater curvature (Lasisi et al 2016). However, given these general differences among the major human groups, De La Mettrie et al (2019) warn that these broad classifications do not adequately represent the full variation in human hair and that eight categories of hair type might represent a better classification scheme.…”

Section: Introductionmentioning

confidence: 99%