Natural checks and balances in man.
D000755:Anemia, Sickle Cell / Q000235:genetics; D005075:Biological Evolution; D003469:Culture; D004463:Ecology; D005260:Female; D005826:Genetics, Medical; D006455:Hemoglobins, Abnormal; D006801:Humans; D008297:Male; D011155:Population Control; D011156:Population Density; D012744:Sex Ratio
D006455:Hemoglobins, Abnormal