The aloof and elusive nature of cats is perhaps their most distinctive feature, endearing to some and exasperating to others. Despite such mercurial tendencies, the house cat is the most popular pet in the world. A third of American households have feline members, and more than 600 million cats live among humans worldwide. Yet as familiar as these animals are, a complete understanding of their origins has proved elusive. Whereas other once wild animals were domesticated for their milk, meat, wool or labor, cats contribute virtually nothing in the way of sustenance or work. How, then, did they become fixtures in our homes?