Over the course of her study , Goodall found evidence of mental traits in chimpanzees such as reasoned thought , abstraction , generalization , symbolic representation , and even the concept of self . All these were thought to be uniquely human abilities . Over the course of her study , Goodall found evidence of mental traits in chimpanzees such as reasoned thought , abstraction , generalization , symbolic representation , and even the concept of self , all previously thought to be uniquely human abilities .