Sickle Cell Disease and Evolution
Explore sickle cell disease and its evolutionary basis in greater depth by watching the videos and reading the article (links below). Also, make sure to consult the section on sickle cell and malaria in Chapters 4 (p. 22) and 14 (pp. 534-538). Then answer the four questions below.
1. Sickle cell anemia follows a single-gene pattern of inheritance, with two alleles: one allele (S) produces normal hemoglobin, and the other (s) produces abnormal hemoglobin. Describe the phenotype outcome for each of the three possible genotypes (SS, Ss, and ss), with regard to sickle cell anemia and malaria.
2. How did human farming influence the evolution of the sickle cell allele in human populations?
3. Malaria is a deadly disease in its own right. According to the video on malaria, natural selection, and new medicine, what have scientists learned about malaria from studying the human genome as well as that of the malaria parasite? How can they use evolution to design new medical treatments?
4. Looking to the future, what changes to the frequency of the sickle-cell allele do you envision as most likely, and why? (In other words, do you envision it becoming more common or less common in human populations?) What factors (technology, climate change, etc) might be driving those changes?