Why do humans all over the world take in and nurture other animals? This behavior might seem maladaptive--after all, every mouthful given to another species is one that you cannot eat--but in this heartening new study, acclaimed anthropologist Pat Shipman reveals that our propensity to domesticate and care for other animals is in fact among our species' greatest strengths. For the last 2.6 million years, Shipman explains, humans who coexisted with...