For going on two decades, Scientific American’s “Ask the Experts” column has been answering reader questions on all fields of science. We’ve taken your questions from the basic to the esoteric and reached out to top scientists, professors, and researchers to find out why the sky is blue or whether we really only use 10 percent of our brains.

Now, we’ve combed through our archives and have compiled some of the most interesting questions (and answers) into a series of books. Organized by subject, each title provides short, easily digestible answers to questions on that particular branch of the sciences.

The Human Body and Mind is the third book in this series, and it tackles questions about our own strange and mysterious biology. Our experts field queries on evolution, bodily quirks, and psychological feats. Have you ever wondered why humans lost their body hair? Curious about what causes a hangover? Or what makes that popping sound when we crack our knuckles? What about the oft-cited maxim that we only use 10 percent of our brains? Professors, scientists, and biologists provide answers that are at once accurate, understandable, and sometimes just plain funny.