What if there were no sea stars? What if there were no wildebeest? How does one species affect all others? These were questions asked by biologists in the early twentieth century and later took on ecological significance as well. These questions and the stories of the scientists who asked them are the subject of The Serengeti Rules by Sean B. Carroll and also adapted into a documentary.

The book is an exploration of how biological and ecological processes keep both bodies and ecosystems in balance and what happens when that balance is disturbed. The early part of the book focuses on biology and how scientists from the early to mid twentieth century investigated how physiological processes were regulated. This includes microbiologist Jacques Monod who discovered that certain enzymes limit bacteria’s ability to digest certain sugars, thereby regulating their populations. Later, several biologists applied many of the same concepts to ecology and performed experiments as to how food webs and certain species dubbed “keystones” by biologist Robert Paine could affect the entire ecosystem. Paine removed sea stars from tidal pools, which allowed the mussels they preyed on to outcompete all other species and seriously reduced biodiversity.

The book is written for the general population and scientific concepts and terms are explained well. In addition, diagrams and photographs are also included. The scientists featured lived at different times, in different countries, and pursued different research. But they shared a profound curiosity and a great love of the natural world. These scientists and their stories include microbiologist Jacques Monod, who served in the French Resistance during World War II, cancer researcher Janet Davison Rowley, who cut out pictures of chromosomes on the kitchen table, and biologist Tony Sinclair who sneaked out of his Tanzanian boarding school to collect beetles.

The book illustrates how a knowledge of “the Serengeti rules” is necessary to understanding the connections between species and the environments in which they live. With this knowledge, it is possible to understand our own role in the world in which we live, restore damaged ecosystems, and have vibrant planet for many generations to come.