Animals·Posted on Jun 4, 201220 Sloth Smiles, Revealed!The mysterious Mona Lisas of the animal world have finally shared the secrets behind those amazing smiles. We have the exclusive scoop:by Summer Anne BurtonBuzzFeed StaffLinkFacebookPinterestTwitterMail 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.