Human skin pigmentation as an adaptation to UV radiation

Dados Bibliográficos

ID23337896
AutoresNina G Jablonski (Department of Anthropology, Pennsylvania State University, University Park, PA 16802), Nina Jablonski (0000-0001-7644-874X, Department of Anthropology, Pennsylvania State University, University Park, PA 16802), George Chaplin (0000-0002-7341-7742, Department of Anthropology, Pennsylvania State University, University Park, PA 16802)
Ano2010
Volume107
Fascículosupplement_2
Páginas8962-8968
Data de publicação2010-05-11
Peer ReviewedSim
Open AccessSim
TipoARTICLE
PeriódicoProceedings of the National Academy of Sciences (JOURNAL)
Identificadores do periódicoISSN: 0027-8424 • E-ISSN: 1091-6490
EditoraNational Academy of Sciences (PUBLISHER • US)
DOI10.1073/pnas.0914628107
PMID20445093
PMCIDPMC3024016
OpenAlexW2127501217
IdiomaEN
Citações recebidas63
Referências citadas72

Human skin pigmentation is the product of two clines produced by natural selection to adjust levels of constitutive pigmentation to levels of UV radiation (UVR). One cline was generated by high UVR near the equator and led to the evolution of dark, photoprotective, eumelanin-rich pigmentation. The other was produced by the requirement for UVB photons to sustain cutaneous photosynthesis of vitamin D 3 in low-UVB environments, and resulted in the evolution of depigmented skin. As hominins dispersed outside of the tropics, they experienced different intensities and seasonal mixtures of UVA and UVB. Extreme UVA throughout the year and two equinoctial peaks of UVB prevail within the tropics. Under these conditions, the primary selective pressure was to protect folate by maintaining dark pigmentation. Photolysis of folate and its main serum form of 5-methylhydrofolate is caused by UVR and by reactive oxygen species generated by UVA. Competition for folate between the needs for cell division, DNA repair, and melanogenesis is severe under stressful, high-UVR conditions and is exacerbated by dietary insufficiency. Outside of tropical latitudes, UVB levels are generally low and peak only once during the year. The populations exhibiting maximally depigmented skin are those inhabiting environments with the lowest annual and summer peak levels of UVB. Development of facultative pigmentation (tanning) was important to populations settling between roughly 23° and 46° , where levels of UVB varied strongly according to season. Depigmented and tannable skin evolved numerous times in hominin evolution via independent genetic pathways under positive selection.

Adaptation (eye) · Biology · Botany · Evolutionary biology · Facultative · Human skin · Natural selection · Photoprotection · Photosynthesis · Population · Acne and Rosacea Treatments and Effects · Genetics · Medicine · melanin and skin pigmentation · Skin Protection and Aging