Orangutan
The largest arboreal creature in the world, the orangutan has probably never lived anywhere else but the trees.
Wildly mobile shoulder, knee and hip joints create a climbing machine that spends approximately 90% of its life high above ground. The thick forests of Borneo and Sumatra provide the perfect environment for this soulful, fruit-eating ape.
The orangutan developed quite separately from human beings, but shares some rare features with us that peak the interest.
Orangutans live in a relatively peaceful society without allot of the struggle for sexual dominance that formulate the motivations of many other mammals. They have somewhat of an open sexual policy, very little inter-species violence or conflict, and in a bit of a stunner, actually have intercourse face to face more often percentage-wise than any other creature on land besides the human being.