Answer:
A research study by Dr. Tony Allison proved that there was a connection between infectious parasitic disease, malaria and genetic disease, sickle cell anemia. As the malarial parasite was more common in East Africa, hence sickle cell became more prevalent in Est Africa. After collecting samples, Dr. Tony Allison found that children carrying the sickle cell allele had a lower parasite count, as if they were partially protected against malaria.