申論題

3. Sickle cell disease is a group of inherited red blood cell disorders. Healthy red blood cells are round, and they move through small blood vessels to carry oxygen to all parts of the body. Researchers found that the sickle cell gene is especially prevalent in areas of Africa hard-hit by malaria. In some regions, as much as 40 percent of the population carries at least one HbS gene. (10 points)

(1). In three to five sentences, explain why sickle cell disease became so prevalent in certain East African populations.