Skin Colour Does Not Define Ethnicity: Quantifying Variation and Overlap Across Diverse Populations

Area of Science:

• Anthropometry
• Human genetics
• Population studies

Background:

• Skin color is a key human trait historically linked to ethnicity.
• Its reliability as a classification tool for ethnicity is questionable.

Purpose of the Study:

• To quantitatively analyze skin reflectance data to assess ethnic group overlap.
• To evaluate the validity of skin color as a sole determinant of ethnicity.

Main Methods:

• Analysis of over 14,000 skin reflectance measurements from the International Skin Spectra Archive (ISSA).
• Utilized a standard color space modeling human visual perception.
• Assessed intragroup variation and intergroup overlap using individual perceptual differences and group gamut volumes.

Main Results:

• Within-group variability in skin chromaticity and lightness often surpasses between-group differences.
• 89.4% of samples had perceptually indistinguishable counterparts across ethnicities.
• A median shared gamut overlap of 60.5% between groups indicates substantial overlap in skin color distributions.

Conclusions:

• Skin color displays high within-group dispersion and extensive between-group overlap.
• Findings question the use of skin color as a reliable ethnicity indicator.
• Emphasizes the continuous nature of human skin variation beyond simplistic ethnic categories.