African Allele Essay

It is a fact that Central Africa is a rural area while the United States is highly urbanized. This means that diseases are more prominent in the African territory, one of which is the malaria. This widespread illness caused evolution to favor a type of change in the human body to protect it from the deadly virus. This protection is the heterozygous make up of the hemoglobin gene, where one allele is the abnormal one that causes sickle-cell anemia. When comparing three types of persons, one with homozygous normal alleles, another with a heterozygous pair, and finally one with a homozygous pair of abnormal alleles, those with the heterozygous pair would have the greatest chance of surviving the conditions of Africa. Having a pair of normal alleles would not save a human from malaria infection, and having a pair of abnormal alleles would cause sickle-cell anemia that can also kill the patient. Thus, in places such as Africa, the population has quite a number of people having the heterozygous hemoglobin gene. The lower number of sickle-cell allele carriers in the United States can be attributed to two main reasons. First, malaria is not as prominent in the United States as it is in Africa. People then did not adapt that much and this abnormal allele haven’t evolved that much. Another is the intermarriage between Africans and Americans. If an African, who carries the sickle-cell allele, would marry an American having a homozygous healthy gene, their children would only have a 50% chance of getting that trait, as compared to an African-African marriage (both heterozygous sickle-cell alleles), where the chance of getting the allele is 75%.