Book excerpt: A comprehensive, humane, and bemused tour of the dog-human relationship, Dog's Best Friend combines anecdote, research, and reportage to illuminate our complex rapport with our cherished canine companions. Tracking our national obsession with an animal that now outnumbers children in American households, Mark Derr chronicles the evolution of "the culture of the dog" from the prehistoric domestication of tamed wolves to the modern horrors of overbreeding and inbreeding. Passionate about his subject and intent on sharing his zeal, Derr defends dogs with wit and flare, producing here a quirky, informative, and fitting tribute to our love affair with canines big and small.