Chimpanzees have helped humans in more ways than you might think. They’ve helped us discovered things about ourselves and proved time and time again that they are incredible creatures. Linda Koebner spent her life studying these amazing animals. She first met chimpanzees Doll and Swing when she was a student. Time has passed, and Linda went on her separate way, but the bond between them remained strong. After 18 years, Linda went back to visit Doll and swing. And believe it or not, the chimpanzees still recognized their old friend. You need to see this!