Rats. They snack on garbage and spread disease, and no matter how many traps we set, they keep coming back. But for some people, rats aren’t pests—they’re potential employees. Inspector Monique Hammerslag of the Dutch National Police force tells us about the team of police rats she’s training. And Aaron Blaisdell, professor of comparative psychology at the University of California, Los Angeles, describes the surprising reasoning abilities of the rat—and what exactly makes them such good workers.