Explore sickle cell disease and its evolutionary basis in greater depth by watching the video and reading the article (links below). Also, make sure to consult the section on the sickle cell and malaria in Chapters 4 (p. 129) and 14 (pp. 536-540). Then answer the three questions below. You may either type your answers into the text box or attach your responses in a file and upload.
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. 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?