EVOLUTION OF MAN 225 



bodied, long-armed specialists in brachiation (swinging through the tree- 

 tops by their arms) (Fig. 11.1). 



During Miocene and on into Pliocene times there lived in various parts 

 of Africa, Europe, and India a varied assemblage of apes classified 

 together in the subfamily Dryopithecinae. Collectively they are believed 

 to have included the ancestors of the modern orang-utan, chimpanzee, 

 and gorilla. Of these the orang-utan, inhabitant of the rain forests of 

 Sumatra and Borneo, is so unlike his African relatives that he is believed 

 to have gone his separate way since early Miocene times. Others of the 

 Dryopithecinae were ancestral to the African apes: gorilla and 

 chimpanzee. In particular, one of the group named Proconsul, living in 

 Africa in early Miocene times, shows characteristics indicating its probable 

 ancestry of these apes. The chimpanzee and gorilla are so similar that they 

 are thought to have diverged from a common ancestor fairly recently, in 

 early Pleistocene or late Pliocene, as Fig. 11.2 indicates. 



Ancestry of Man 



Having established the probable ancestries of monkeys and apes we 

 come now to the question of the ancestry of man. This portion of our 

 diagram (Fig. 11.2) is represented by a broad "channel" which to be more 

 realistic should be subdivided into an interlacing network of smaller 

 channels twisting, turning, dividing, and recombining in most complicated 

 fashion (cf. Fig. 11.16). Names have been placed at various points along 

 this channel to Homo sapiens. The names represent progressive levels of 

 development toward the Homo sapiens stage and in some instances, at 

 least, may well represent actual ancestors. It will be noted that the name 

 of Parapitheciis is so placed as to indicate that this monkey-ape was 

 ancestral to man. Our limited knowledge of Parapithecus indicates that 

 it was so primitive in its primate characteristics that it represents a stage in 

 evolution in which Old World monkeys, apes, and ancestors of man were 

 not clearly separated. Indicating that it was ancestral to all three is in ac- 

 cord with the view that man shared common ancestry with monkeys and 

 apes. This is the most widely held view, though a few investigators have 

 maintained that man is not related to monkeys and apes, but has followed 

 a separate evolutionary line springing directly from tarsiers and lemurs. 



What of other human ancestors in the Oligocene? Were there forms 

 ancestral to both men and apes? Or had the ancestral line leading to man 

 already separated from that leading to apes? Until more Oligocene fossils 

 are found we can not answer these questions. 



