Chimpanzees are often incorrectly called monkeys, but they are actually in the great ape family just like us. The other great apes are orangutans and gorillas. There is only one species of human alive at present: homo sapiens. In the past, many scientists tried to argue that there were several species of human, and would often hasten to add that they themselves belonged to the ‘superior’ species. However, all humans can produce fertile children and so we are all the same species. Chimpanzees, on the other hand, are actually two species: pan troglodytes, the common chimpanzee, and pan paniscus, the gracile chimpanzee or bonobo. These two types of chimpanzee are completely separate species. Humans and both chimpanzee species evolved from a common ancestor, possibly sahelanthropus tchadensis, between five and seven million years ago. Only fossils of this ancestor remain.