Does sickle cell affect some population groups more than others?
It affects South America and Africa more than anywhere else. The peoples in those areas have adapted to have it. Therefore, many African people have sickle cell. The reason they have adapted to have sickle cell is due to malaria. Malaria is a protozoa that infects people that do not have sickle cell. Malaria needs blood cells that are donut in shape, whereas sickle cell blood cells are crescent shape. In those areas people with sickle cell have a better chance of living than people who do not have it, so they reproduce and make more kids that have sickle cell, while malaria kills people in a year or two after they contract it. I hope that makes sense.
