The apes and monkeys already appear to have been differentiated at the beginning of the Cainozoic Age, and there are a number of Oligocene and Miocene apes whose relations to one another and to the human line have still to be made out. Among these we may mention _Dryopithecus_ of the Miocene Age, with a very human-looking jaw. In the Siwalik Hills of northern India remains of some very interesting apes have been found, of which _Sivapithecus_ and _Palæopithecus_ were possibly related closely to the human ancestor. Possibly these animals already used implements. Charles Darwin represents baboons as opening nuts by breaking them with stones, using stakes to prize up rocks in the hunt for insects, and striking blows with sticks and stones.[21] The chimpanzee makes itself a sort of tree hut by intertwining branches. Stones apparently chipped for use have been found in strata of Oligocene Age at Boncelles in Belgium. Possibly the implement-using disposition was already present in the Mesozoic ancestry from which we are descended.[22] § 2 Among the earliest evidences of some creature, either human or at least more man-like than any living ape upon earth, are a number of flints and stones very roughly chipped and shaped so as to be held in the hand. These were probably used as hand-axes. These early implements (“Eoliths”) are often so crude and simple that there was for a long time a controversy whether they were to be regarded as natural or artificial productions.[23] The date of the earliest of them is put by geologists as Pliocene--that is to say, _before the First Glacial Age_. They occur also throughout the First Interglacial period. We know of no bones or other remains in Europe or America of the quasi-human beings of half a million years ago, who made and used these implements. They used them to hammer with, perhaps they used them to fight with, and perhaps they used bits of wood for similar purposes.[24]