| | / / | | Unknown Pliocene | / / | | ancestors of man. | / / | | | | / / | MIOCENE | | Primitive anthropoids / AGE. Earliest Gibbons | of Asia and Europe. / of Europe. | | / / (_Pliopithecus_). | / / / | | / / / +--------------+---------------------- / | / OLIGOCENE. Ancestral anthropoids Small monkeys of Egypt of Egypt. (_Propliopithecus_). / | / +-----------+---------------- | Unknown ancestral stock of the Old World primates, including man. From the unknown and ancestral stock of the anthropoid apes and man the GIBBON was the first to branch off in Oligocene times; the ORANG then branched off in a widely different direction. The stem of the CHIMPANZEE and of the GORILLA branched off at a more recent date and is more nearly allied to that of man. Five early human races have been found in Europe in Glacial or Pleistocene times, but no traces of other primates except the macaques, which are related to the lower division of the baboons, have been found in Europe in Pleistocene times. Modified after Gregory. (For latest discovery see Appendix, Note VII.)] [Illustration: FIG. 20. The Gorilla. An immature female, about three years of age, showing none of the adult male characteristics. Photograph from the New York Zoological Park.] We observe also in the chimpanzee a contrast between the grasping power of the big toe, which is a kind of thumb, and the lack of that power in the hand, in which the thumb is nearly useless; in all apes this function is characteristic of the foot, in man of the hand alone. The _opposable thumb_, with its power of bringing the thumb against each of the fingers, is the one character which is lacking in every one of the anthropoid apes and which was early developed among the ancestors of man.