The evolutionary relationships of man and orang-utans.

Man shares uniquely few morphological features with either the chimpanzee or the gorilla, whereas there are many features that suggest affinities between man and the orang-utan, to whom the fossil Sivapithecus appears to be closely related. If these are unique features, inclusion of Sivapithecus, man and the orang-utan in a single clade, distinct from that containing the African apes, is justified but contrary to current opinion.