The process of evolution occurred to drive the bonobos to cooperate with one another as the chimps remained more war like, due to the food source available to them. The cooperative bonobos passed on their genes to offspring as the fighting chimps passed on their genes to offspring. They evolved in different social directions. A drought that occurred two million years ago most likely caused the gorillas to leave the habitat where the chimps were living in trees allowing some chimps to evolve into bonobos feeding on the ground and forming bonds with one another. True False .