Shape Variability and Classification of Human Hair: A Worldwide Approach

January 2007 in “ Human biology ”

R. De La Mettrie, D. Saint‐Légér, Genevievève Loussouarn, Anne-Lise Garcel, Crystal Porter, André Langaney

human hair curve diameter curl index number of waves hair classification cosmetic sciences forensic sciences genetic variation

Studysummary This study proposes a new, objective method to classify human hair into eight categories based on specific shape measurements, rather than traditional ethnicity-based classifications.

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The study aimed to develop a more scientific and factual approach to classifying human hair based on physical features rather than traditional ethnic categories. Researchers analyzed hair from 1,442 subjects across 18 countries, using three descriptors: curve diameter (CD), curl index (i), and number of waves (w). This method resulted in a classification system with eight well-defined hair categories, providing a more objective and reliable standard for use in cosmetic and forensic sciences. The new classification also aimed to explore whether hair shape diversity aligns with continuous geographic and historical patterns of human genetic variation or shows significant discontinuities between large human subdivisions.

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Research cited in this study

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78 citations , June 2003 in “Journal of the American Academy of Dermatology”

This article reviews the autonomous functioning and complex interactions within hair follicles, emphasizing their unique composition and differentiation pathways, but does not report new research findings.

research Ethnic Hair Update: Past and Present

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This article reviews common hair-care practices among African American patients and discusses how these practices relate to hair and scalp disorders, without presenting new clinical research.

research Human Hair Form: Morphology Revealed by Light and Scanning Electron Microscopy and Computer-Aided Three-Dimensional Reconstruction

27 citations , September 1988 in “PubMed”

In this study, researchers used three-dimensional reconstruction to show that the shape of the hair follicle determines the hair's form, with variations observed among different racial groups.