Superfamily comprising the Hylobatidae (gibbons) and Hominidae (humans, apes, and their immediate ancestors). The hominids are believed to be descended from a common stock of ‘great apes’ which diverged to form distinct Asian and African lines, the African line dividing again 4–6 million years ago into the African apes and the ancestors of modern humans. The hominoids lack tails and cheek pouches; have opposable thumbs (reduced in some species); and differ from the Cercopithecidae (Old World monkeys) in having less-specialized dentition, larger heads, longer limbs, and wider chests which some authorities believe they inherited from ancestral brachiating forms. Today only the Hylobatidae (gibbons) are specialized brachiators (i.e. swing from branches hand over hand).