Animals fall in love, establish rules for fair play, exchange valued goods and services, hold "funerals" for fallen comrades, deploy sex as a weapon, and communicate with one another using rich vocabularies. Animals also get jealous and violent or greedy and callous and develop irrational phobias, just like us. Monkeys address inequality, wolves miss each other, elephants grieve for their dead, and prairie dogs name the humans they encounter. Human...