title: Nature's experiments and medical research.
mesh_terms: D000349:Africa; D002051:Burkitt Lymphoma / Q000453:epidemiology / Q000209:etiology; D003327:Coronary Disease / Q000453:epidemiology / Q000209:etiology; D003906:Developing Countries; D004194:Disease; D004777:Environment; D006801:Humans; D007109:Immunity; D008288:Malaria / Q000453:epidemiology / Q000276:immunology; D008511:Medicine; D009748:Nutrition Disorders / Q000276:immunology; D012106:Research; D012959:Socioeconomic Factors