Cladistics—the science of comparison—is transforming the way paleontologists view evolution. In Search of Deep Time strips away conventional assumptions about the evolution of life to reveal a world that may be far stranger and more humbling than had been previously imagined. The concept of deep time was first used by John McPhee to describe intervals of time incomprehensibly greater than our daily experience. Henry Gee explains the rise of cladistics as the best technique for making sense of the organic changes that unfold within deep time.