Ape years ago (Mya) the clades diverged into newer clades. The lesser apes are the gibbon family, Hylobatidae, of sixteen species; all are native to Asia. Their major differentiating characteristic is their long arms, which they use to brachiate through trees. Their wrists are ball and socket joints as an evolutionary adaptation to their arboreal lifestyle. Generally smaller than the African apes, the largest gibbon, the siamang, weighs up to ; in comparison, the smallest "great ape", the bonobo, is . Formerly, all the great apes except humans were classified as the family Pongidae, which conveniently provided for separating the human
The Ape Man Ford) and photographer Billie Mason (Louise Currie) are on assignment (initially suggested by an odd character who seems to have no relevance to the plot) investigating the recent disappearance of Dr. Brewster. Before interviewing Brewster's sister Agatha, a "ghost-hunter", they hear strange sounds outside the house. After Dr. Randall's butler is murdered and the only clue is a fistful of ape-like hair, Carter deduces that the ghostly sounds they heard may well have been from an ape. Carter returns to investigate further. Dr. Randall informs Agatha that he will not help her brother again - and will go to the