{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T01:27:17Z","timestamp":1787016437602,"version":"build-2736575974"},"reference-count":17,"publisher":"American Association for the Advancement of Science (AAAS)","issue":"4356","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Science"],"published-print":{"date-parts":[[1978,8,18]]},"abstract":"<jats:p>Human populations native to areas of intense sunlight tend to be heavily melanized. Previous explanations for this relationship have invoked only weak selective pressures. To test the hypothesis that dark pigmentation may protect against photolysis of crucial light-sensitive vitamins and metabolites by ultraviolet light, folate was used as a model. It was found that exposure of human plasma in vitro to simulated strong sunlight causes 30 to 50 percent loss of folate within 60 minutes. Furthermore, light-skinned patients exposed to ultraviolet light for dermatologic disorders have abnormally low serum folate concentrations, suggesting that photolysis may also occur in vivo. Deficiency of folate, which occurs in many marginally nourished populations, causes severe anemia, fetal wastage, frank infertility, and maternal mortality. Prevention of ultraviolet photolysis of folate and other light-sensitive nutrients by dark skin may be sufficient explanation for the maintenance of this characteristic in human groups indigenous to regions of intense solar radiation.<\/jats:p>","DOI":"10.1126\/science.675247","type":"journal-article","created":{"date-parts":[[2006,10,5]],"date-time":"2006-10-05T12:35:25Z","timestamp":1160051725000},"page":"625-626","source":"Crossref","is-referenced-by-count":155,"title":["Skin Color and Nutrient Photolysis: An Evolutionary Hypothesis"],"prefix":"10.1126","volume":"201","author":[{"given":"Richard F.","family":"Branda","sequence":"first","affiliation":[{"name":"Department of Medicine, University of Minnesota, Minneapolis 55455"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John W.","family":"Eaton","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of Minnesota, Minneapolis 55455"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"221","reference":[{"key":"e_1_2_1_1_1","doi-asserted-by":"crossref","first-page":"192","DOI":"10.1038\/jid.1969.133","volume":"53","year":"1969","unstructured":"BERGER, D.S., SPECIFICATION AND DESIGN OF SOLAR ULTRAVIOLET SIMULATORS, JOURNAL OF INVESTIGATIVE DERMATOLOGY 53: 192 (1969).","journal-title":"JOURNAL OF INVESTIGATIVE DERMATOLOGY"},{"key":"e_1_2_1_2_1","first-page":"411","year":"1969","unstructured":"BLAKELY, R.L., BIOCH FOLIC ACID REL: 411 (1969).","journal-title":"BIOCH FOLIC ACID REL"},{"key":"e_1_2_1_3_1","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1086\/282252","volume":"97","year":"1963","unstructured":"BRACE, C.L., STRUCTURAL REDUCTION IN EVOLUTION, AMERICAN NATURALIST 97: 39 (1963).","journal-title":"AMERICAN NATURALIST"},{"key":"e_1_2_1_4_1","first-page":"271","year":"1965","unstructured":"BRACE, C.L., MANS EVOLUTION INTRO: 271 (1965).","journal-title":"MANS EVOLUTION INTRO"},{"key":"e_1_2_1_5_1","unstructured":"CAVALLISFORZA L.L. 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