Earth and Life: A Four Billion Year Conversation

Geobiologist Knoll (A Brief History of Earth) offers a stimulating primer on how interactions between the planet’s physical environment and living beings have shaped the world throughout time. He argues that life has influenced Earth in big and small ways, just as the physical Earth has shaped ecology and evolution. He begins by explaining how carbon, nitrogen, phosphorous, water, and oxygen cycle through organisms and the environment. But these cycles haven’t always existed; scientists believe, for example, that oxygen began accumulating in the atmosphere 2.4 billion years ago when cyanobacteria evolved to release the element as a waste product. This so-called “Great Oxygenation Event” transformed the planet, paving the way for the evolution of organisms that rely on oxygen. Elsewhere, Knoll reveals how sunlight, plate tectonics, ocean circulation, and organisms have interacted to enable the planet to be habitable for most of its history and discusses how humans have disrupted natural patterns through the burning of fossil fuels, resulting in climate change and other environmental maladies. Knoll does an impressive job of lucidly explaining both geological and biological processes, providing necessary background without being pedantic. Readers will be informed and entertained. Photos. (Mar.)