Viruses are the most abundant biological entities on Earth, and arguably the most successful. They are not technically alive, but--as infectious vehicles of genetic information--they have a remarkable capacity to invade, replicate, and evolve within living cells. Synthesizing a large body of recent research, Michael Cordingley goes beyond our familiarity with viral infections to show how viruses spur evolutionary change in their hosts, shape global ecosystems, and influence every domain of life.

In the last few decades, research has revealed that viruses are fundamental to the...