When we think about weapons, we usually think of guns and bombs and swords -- military instruments. But in his book "Animal Weapons: The Evolution of Battle," beetle biologist Doug Emlen gives us an inside look at the weapons that animals use: things like horns and tusks and claws.

The book combines science and military history to show just how much we can learn about our own wars and arms races, by understanding the way animals fight. Emlen joins us on this episode to talk about it.