Where did the human species originate, why are tropical peoples much more diverse than those at polar latitudes, and why are the Japanese so adept at digesting seaweed? Alexander Harcourt answers these questions as he explains how our interaction with our environment explains much about why humans differ from one region of the world to another, not only biologically, but culturally. As Harcourt argues here, humans are often just another primate—one that is "mad, bad, and dangerous to know" for most other animals—and our distribution around the world and the type of organism we are today has been shaped by the same biogeographical forces that shape other species.