Assignment task: Describe the evolutionary interplay between folate and vitamin D. What do scientists infer from the lack of variation in the MC1R gene among African populations? Why are light skinned people at greater risk for skin cancer than dark skinned people? Why might dark skinned people living in high latitude environments need to take a vitamin D supplement? (Note: please always consult your doctor before starting any supplement regimen). Now design a diagram that illustrates the positive and negative selective factors that account for the differences in skin colors among human populations. Diagram: selective factors for skin color variation. Need Assignment Help?