1. For example: Sickle Cell Anemia and Evolution Your name

2. Brief introduction of the disease What is it? Where is it? How much of a problem is it?

3. Proximate Causation The proximate cause of this disease is:

4. Evolutionary Question For example: Why are genes for sickle cell so common, since they cause sickle cell anemia, a devastating disease? Shouldn’t natural selection have removed the sickle cell allele from human populations?

5. Evolutionary Hypothesis One possible answer to those questions: Heterozygote advantage of the sickle cell allele in areas with malaria.

6. Explanation of Evolutionary Hypothesis Heterozygote advantage in sickle cell might work like this… This is an example of ______(for example, “Balancing Selection”, one of the categories of evolutionary medicine hypotheses from the class)

7. Predictions and evidence for this hypothesis If the sickle cell trait provides a benefit in malaria, we should see higher numbers of people with the trait in places with malaria. Evidence for sickle cell trait matches the distribution of malaria.

8. Alternative Hypotheses Sickle cell is not adaptive – it has no benefit – This is not supported by evidence for survival of sickle cell heterozygotes in Africa. Sickle cell is a sporadic mutation – This idea is not supported by the high frequency in the population, way higher than what is expected for sporadic mutation rates.

9. Significance This hypothesis explains the epidemiology of this disease Other gene polymorphisms that affect the red blood cell might also provide benefit in malaria.

10. Summary and Conclusions

11. References