I Contain Multitudes

Every animal, from a human to a squid to a wasp, carries millions of bacteria and other microbes. This book looks at life from the microbes' side and asks what changes when an animal is treated as a crowd of partners instead of a single individual.

Ed Yong, a science writer, moves through a series of examples. Microbes in the body belong to the immune system and help guard against disease. In the deep oceans, creatures with no mouth and no gut rely on microbes for all their energy. Squid get a kind of invisibility cloak from bacteria, beetles use them to fell forests, and worms use them to spread diseases that afflict millions of people.

The argument pushes against the common view of microbes as germs to be wiped out. The microbes that live with us, collectively the microbiome, help form our bodies, guard our health, shape who we are and grant unusual abilities. Yong presents this as the biggest shift in biology since Darwin.

This is popular science, written for general readers, with humor alongside the research. Along the way it introduces the scientists working at the front of the field. It reads as a wide-ranging tour of animals and habitats, with each chapter turning a familiar creature into a small ecosystem.