Inspired by the idea of symbiosis in evolution—that all living things evolve in a series of cooperative relationships—Elizabeth Marshall Thomas takes a journey through the progression of life. Along the way she shares the universal likenesses, experiences, and environments of "Gaia's creatures," from amoebas in plant soil to the pets we love, from proud primates to Homo sapiens hunter-gatherers on the African savanna. Noting that nonhuman life shares characteristics with us, Thomas instead shows that paramecia can learn, and plants can communicate.