John Libbey Eurotext

European Journal of Dermatology

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Diversity in human hair growth, diameter, colour and shape. An in vivo study on young adults from 24 different ethnic groups observed in the five continents Volume 26, numéro 2, March-April 2016

Figure 1

Studied scalp areas localisation.

Figure 2

Hair density (N/cm2, mean ± SD) according to groups.

Figure 3

Telogen % (mean ± SD) according to groups.

Figure 4

Hair growth rate (μm/day, mean ± SD) according to groups.

Figure 5

Hair diameter in μm (mean ± SD) according to groups.

Figure 6

Groups mapping (PCA and HAC). Principal component analysis (PCA) followed by hierarchical ascendant classification (HAC) permitted the two-dimensional localization of mean populations when cross-analysing all three growth parameters (density, telogen % and growth rate), diameter is added as an illustration. Means of populations were localized in one of three distinct clusters corresponding to classical African, (cluster I), Asian (cluster II) and Caucasian (cluster III) hair types, which could then be further differentiated into distinct sub-clusters, including seven clusters in all.

Figure 7

Individual data Continuum (PCA and HAC). The projection of individual hair growth parameters in the clusters previously defined by PCA and HAC (graph 5) demonstrates a complete continuum of data points, where population clusters are not readily apparent, reflecting overall population admixture. As in the previous PCA, in red, green, and blue, African, Asian and Caucasian hair types respectively.