Sloths are known for two traits: being really slow, and seeming to always wear a smile. But they weren't always that way. In prehistoric times, sloths were as big as grizzly bears and ate small animals. But one day, purely by accident, that all changed- thanks to the hero of this story, Great-Great-Great-Grandpa Slumpy Sloth. This is the story of how the sloth became the peaceful, slow-moving, smiling creature we all know and love.