This interview may change how you see yourself. Sure, you might be a man or a woman, married or single. Mostly though, says immunologist Gerald Callahan, you are bacteria. They influence your health; they may even be changing your behavior. Callahan, who teaches at Colorado State University, has a new book about how our immune systems and our infections define us.
Hear why Callahan calls his book "Lousy Sex."
[Image: Wikimedia Commons]
