She says of this revelation, "During the first ten years of the study I had believed […] that the Gombe Stream chimpanzees were, for the most part, rather nicer than human beings, then suddenly we found that chimpanzees could be brutal that they, like us, had a darker side to their nature". These findings revolutionized our knowledge of chimpanzee behaviour. They were further evidence of the social similarities between humans and chimpanzees, albeit in a much darker manner.