Juvenile male chimpanzees have been recorded mounting and copulating with immature chimps. Recent studies show that there are significant brain differences between bonobos and chimps. The zoo has bred and maintained bonobos (pygmy chimps) since 1960. Chimps and humans share only 50% of their parasite and microbe species. Gene duplications account for most of the sequence differences between humans and chimps. Another example of this is with humans and chimps. They are highly territorial and are known to kill other chimps. Will's boss Steven Jacobs terminates the project and has the chimps euthanized. Nobody knew then if chimps could swim. Ant dipping is difficult and some chimps never master it. After the procedure, both chimps were pacified and less violent. She gradually came to enjoy associating with other chimps. Jimmy and Teri walk in to see the chimps escaping. Budongo Trail is a naturalistic enclosure which can house up to 40 chimps. "Dryopithecus" teeth are most similar to those of modern chimps.