Only people who have inherited 2 bad genes (one bad gene from each parent) for hemoglobin have sickle cell anemia. The average life expectancy of someone with sickle cell anemia is around 45 years. If someone inherits one bad gene for hemoglobin and one good gene, they are said to have sickle cell trait. Individuals with sickle cell trait are less susceptible to malaria than individuals who inherit two normal versions of the hemoglobin gene. Given this information, why do you suppose that sickle cell trait and sickle-cell anemia are much more prevalent in the African-American population than in any other race of individuals in America?