Meet Sharon Moalem. He pursues to understand his grandfather's disease thoroughly. His 71-year-old grandfather has Alzheimer's disease and often gets his blood drawn. because he also has hemochromatosis. Hemochromatosis results in a high iron build-up in the blood. This drives him to study biology in college and become a neurologist. Moalem questions why are diseases even placed in the codes of DNA if it only harms the organism. 

Moalem touches on many different diseases and evolutionary changes in the body and how they have affected human life and other species. Whether it's iron deficiency, less vitamin D production, jumping genes, favism, mutations, or epigenetics, Moalem's common question for these conditions and phenomena is how are these traits placed in the genetic genome in the first place. He doesn't find a definite answer but as he moves on, he shows that these answers are complex and overall take more time to understand as time progresses. 

In Conclusion,

Moalem suggests to readers of thinking why this happens and what we can do with it. When thinking about cellular evolution and illnesses, know that everything is created and recreated constantly, humans have complex relationships when it comes to disease, and that everything is interconnected with each other.