Every animal relies on a weapon of some kind-cats have claws, eagles have talons, even the dogs we keep as pets have a respectable set of teeth. In rare cases, we find species whose weapons have become stunningly outsized, some with tusks so massive that those who wield them look like they should collapse under the weight. In Animal Weapons, biologist Douglas Emlen pulls readers into the worlds of these remarkable beasts, trekking through rainforests and mountain passes to unravel the mysteries of their weapons. Along the way, Emlen shows that the essential biology of animal arms races applies to our own weapons, too. A story that begins with biology becomes the story of all weapons, as Emlen seeks to determine where this parallel leaves us today, in a world filled with the deadliest weapons of all time-nuclear, biological, and chemical weapons of mass destruction.