Picture of African Chimpanzee
Chimps and bonobos in Africa are mostly separated by the Congo River, so these species don't interact very often. The Congo River may be a large factor that led to the speciation and split of these two animals and caused them to evolve independently. However, genome tests concluded that the chimps actually had 1% of bonobo DNA in them. This led the scientists to conclude that these two species had two separate interbreeding events in the past that led to the shared DNA. These findings along with the discovery of Neandertal DNA in humans is helping to change the classical definition of a species. More and more evidence has been showing that different species can in fact interbreeed to produce fertile offspring, and is changing the way that evolutionary relationships are being viewed between species.