Charles Darwin developed his evolutionary theories by studying Galapagos finches and fancy pigeons; Alfred Russel Wallace investigated creatures in the Malay Archipelago. Laurel Braitman got her lessons closer to home—by watching her dog. Oliver snapped at flies that only he could see, suffered from debilitating separation anxiety, was prone to aggression, and may even have attempted suicide. Braitman’s experiences with Oliver made her acknowledge a startling connection: non-human animals can lose their minds. And when they do, it often looks a lot like human mental illness. Thankfully, all of us can heal. Braitman spent three years travelling the world in search of emotionally disturbed animals and the people who care for them, finding numerous stories of recovery: parrots that learn how to stop plucking their feathers, dogs that cease licking their tails raw, polar bears that stop swimming in compulsive circles, and great apes that benefit from the help of human psychiatrists. How do these animals recover? The same way we do: with love, medicine, and above all, the knowledge that someone understands why we suffer and what can make us feel better.