My favorite chapter was chapter 3 where Moalem discussed vitamin D and melanin. Being an African-American, I understand that having more melanin blocks the harm of ultraviolet B rays but didn't know that it affected the amount of vitamin D produced. In chapter 3, I learned how the sun is necessary for all humans as it's the number one producer of vitamin D. It even gets rid of the reserve folic acid, a crucial part of cell growth and replication. Melanin helps balance out the right amount of folic acid present in the skin. The location also suggests this as Africans are prone to being darker than Europeans. The closer to the equator, the closer the sun's UVB rays are direct to the skin thus creating thicker and darker melanin barriers for people living in Africa than in Europe.

 Due to the less vitamin D produced in darker-skinned people, a protein of apolipoprotein E (ApoE4) has evolved intp those individuals. I find this interesting as the climate plays a bigger role in vitamin D production than I thought but in reality, evolution has helped create an adaptation for those that don't produce the same way. And it's continuously passed down from generation to generation.