There’s more. When beavers build their dams and ponds, they create new habitat conducive to greater botanical and wildlife diversity. That’s why The Beav is known as a keystone species. That’s why the world was a very different place when they were around — before millions of them were trapped, before they disappeared from vast stretches of North America, before we filled in wetlands, before we built homes and driveways and highways in places we should have left alone.