Survival of the Sickest
William Morrow, 2007
Reviewed by Alece Kaplan, July 2007
The concept of “survival of the fittest” purports that living beings equipped with specialized characteristics designed to help them survive and reproduce have an advantage over beings which lack these beneficial characteristics. According to this model, evolution favors traits that help a being survive and pass on their genetic material to their offspring. If this is in fact the case, one could suppose that over time human beings would become consistently healthier, with debilitating diseases and conditions slowly weeded out through natural selection. However, devastating and even fatal hereditary conditions have persisted throughout time, passed down from one generation to the next. In “Survival of the Sickest”, Dr. Sharon Moalem offers an explanation for this phenomenon that is still consistent with evolutionary theory.
In an engaging, easy to read style, Dr. Moalem explores common hereditary conditions, delving into the history of each condition in an effort to discover its place in the evolutionary timeline of humankind. The end result of each examination is the same- the condition originally evolved, or persisted throughout the generations, because at one point in time it provided its victim a significant advantage. Whether it’s the blood disease hemochromatosis providing an edge during outbreaks of the Black Death by depriving the bubonic plague bacteria of the iron it needs to survive, juvenile diabetes helping people endure the ice age by lowering the freezing point of blood, or sickle cell anemia providing resistance to malaria due to the spleen’s eradication of red blood cells with an abnormal sickle shape, simultaneously eliminating the malaria parasite, the hereditary conditions that make life miserable for people in the 21st century ensured the survival of their ancestors, centuries ago.