Bonobo!

Check out a fascinating page about the Bonobo monkey, which is endangered and only is found in the wild in the Democratic Republic of Congo. Along with the Common Chimpanzee, the Bonobo is the closest relative to humans.

Bonobo Sex and Society by Frans B. M. de Waal, excerpt:

Sex, it turned out, is the key to the social life of the bonobo. The first suggestion that the sexual behavior of bonobos is different had come from observations at European zoos. Wrapping their findings in Latin, primatologists Eduard Tratz and Heinz Heck reported in 1954 that the chimpanzees at Hellabrun mated more canum (like dogs) and bonobos more hominum (like people). In those days, face-to- face copulation was considered uniquely human, a cultural innovation that needed to be taught to preliterate people (hence the term "missionary position"). These early studies, written in German, were ignored by the international scientific establishment. The bonobo's humanlike sexuality needed to be rediscovered in the 1970s before it became accepted as characteristic of the species.

Frans de Waal quotes:

"The possibility that empathy resides in parts of the brain so ancient that we share them with rats should give pause to anyone comparing politicians with those poor, underestimated creatures."

"I've argued that many of what philosophers call moral sentiments can be seen in other species. In chimpanzees and other animals, you see examples of sympathy, empathy, reciprocity, a willingness to follow social rules. Dogs are a good example of a species that have and obey social rules; that's why we like them so much, even though they're large carnivores."

"To endow animals with human emotions has long been a scientific taboo. But if we do not, we risk missing something fundamental, about both animals and us."
from "Are We in Anthropodenial?"