A person with sickle trait is more likely to survive than a person without the sickle trait that is a normal person. The sickle trait has been scientifically proven to protect against malaria. Individuals with the sickle cell trait have a different type of hemoglobin compared to normal people. They have a mutation in the gene that codes for the protein hemoglobin resulting in either having sickle cell disease or being carriers that is having the sickle trait. They have hemoglobin S instead of hemoglobin A. So if a person is a carrier, they have both hemoglobin A and S and hence have the trait of hemoglobinAS whilst normal individuals have AA and those with sickle cell disease have SS. It is actually believed that the sickle cell trait evolved as a result to protect the population against malaria even though there are huge consequences in having the disease. A piece of research done in Mali has shown that individuals with AS suffer from less malaria than those with AA.
The mechanisms of protection against malaria are not fully understood but recently research has shown that there are factors in individuals with AS and SS that stop the parasite from growing. These factors are actually expressed more in AS and SS individuals than in AA individuals.
I guess this could be testament to the theory of survival of the fittest where have a particular trait is actually advantageous for ones survival. #Darwinstheoriesattherebest 🙂