Chimpanzees evolved from a bigger ape. Apes evolved to be frugivores but the gorilla will also eat leaves and other parts of a plant, most likely because they are too big to climb trees to harvest fruits safely, so they are more like herbivores than frugivores. The chimpanzee is excluded from the best habitats in an area by their larger cousin, the gorilla. As a result chimps have to supplement their diet by hunting monkeys and small primates for food. If they do not eat meat, they would not get enough calories or protein. OTOH, the gorilla, having the best habitat for themselves, spend very little time looking for food daily and they are not known to eat meat. Male gorillas spend their leisure time playing with their own young and also trying to entice females from other groups to join their own harem. Male chimps do not have time to play with their own young because they have to figure out how to fill their stomachs. For that they have bigger brains than the gorilla. Besides, male chimps do not even know who is the father of any young chimp, as males bond with each other and they do not fight over the right to mate with females. Females mate with multiple males to make sure that the males all think that they may be the father and so will not harm the young chimp out of jealousy. Females like meat so much that they often offer to have sex with male chimps in exchange for meat.
The bonobo evolved from a common chimp, but bonobos live across the Congo River from the chimps and gorillas. The bonobo therefore has the best habitats in their neighborhood all to themselves, and they do not have to fight off chimps or gorillas, because gorillas and chimps cannot swim. Bonobos seem to like water, and they may have swam or driftede across the river to their current location a long time ago. Bonobos have all the plant food they need, and they do not eat meat, unlike chimps. Bonobos have so much time that they spend it by having sex with everybody in the troop in their spare time. They also are not as territorial as chimps. Chimps will gang up and kill males from neighboring troops. Bonobos in contrast would rather make love than to make war.