"Goodall documented a conflict between two groups that lasted several years. The males of one of the groups invaded and gradually, one by one, isolated and killed first the males and then the other members of the other group, finally annexing its territory. Instances of murderous aggression, even by females, especially against infants that were not their own, have also been observed within the group. Finally, on occasion, chimpanzees would threaten with, beat with and throw sticks and stones. From being humans' idyllic antithesis in the 1960s' culture, the friendly, playfully naughty, and intelligent, but also jealous, quarrelsome, killing, and even warring, chimpanzees now increasingly mirror what we have commonly thought about ourselves."