Why do mainly black people have sickle cell anaemia?

Where it started.: Malaria across the central belt of the africa acted as a form of selective pressure, influencing the genetic development of resistance to the disease and thereby enabling the survival of human populations. Malaria protection evolved only in people who carried genes for sickle-cell anemia. Africans without the sickle-cell genes died from malaria, leading to a genetic advantage.

Survival advantage: Sickle cell is due to a single genetic mutation. This may have occurred in several areas, but in africa, those who were born with sickle cell trait were more likely to survive a malaria infection. Thus, there are many people with sickle trait in africa. So most of sickle trait occurred originally in africa, but now this disease is seen in many other ethnic groups.