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12:37
Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
The evolution of human skin coloration
1Department of Anthropology, California Academy of Sciences, Golden Gate Park, San Francisco, CA 94118-4599, USA. njablonski@calacademy.org
Journal of Human Evolution
|July 18, 2000
Summary
Human skin color variation is adaptive, evolving to regulate ultraviolet radiation (UV) penetration for fitness. Lighter skin evolved outside tropics for vitamin D synthesis, while darker skin protects folate. Skin color is not indicative of phylogenetic relationships.
Area of Science:
- Human evolutionary biology
- Anthropology
- Dermatology
Background:
- Human skin color variation has been historically used to define races.
- Previous understanding lacked quantitative data linking skin color to environmental factors.
Purpose of the Study:
- To quantitatively test hypotheses on the adaptive distribution of indigenous human skin colors relative to ultraviolet (UV) radiation levels.
- To investigate the role of melanin pigmentation in regulating UV radiation effects on skin and its physiological consequences.
Main Methods:
- Utilized remotely sensed data on UV radiation levels globally.
- Correlated UV levels with quantitative measurements of indigenous skin reflectance.
- Analyzed skin reflectance data across different populations and sexes.
Main Results:
- Skin reflectance strongly correlates with absolute latitude and UV radiation levels, particularly at 545 nm.
- Melanin pigmentation primarily regulates UV effects on dermal blood vessels.
- Females exhibit lighter skin than males across populations.
- Skin coloration represents a compromise between UV protection and vitamin D synthesis.
Conclusions:
- Human skin color is adaptive and labile, evolving in response to UV radiation.
- Early hominids evolved dark skin for thermoregulation and folate protection.
- Depigmentation evolved for vitamin D synthesis as hominids migrated.
- Skin color is unsuitable for determining phylogenetic relationships among modern human groups.
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