We all know the type—pushy people who elbow their way to the front of the line or cut in on us when we are driving. And then there are those who have less assertive personalities, and happily defer to others. Animals show similar behavioral variety, according to biologist John Shivik. In his new book Mousy Cats and Sheepish Coyotes, he explores the science of animal personalities and how it helps balance nature’s necessary tension between individualism and cooperation—and underpins important aspects of evolution. (Find out how we know that animals think and feel.)

Speaking from his home in Logan, Utah, Shivik explains why the most macho bluebirds don’t always get the girl, how some dolphins showed marked