There was, moreover, a jaw-bone among these scattered remains, which was at first assumed naturally enough to belong to _Eoanthropus_, but which it was afterwards suggested was probably that of a chimpanzee. It is extraordinarily like that of a chimpanzee, but Dr. Keith, one of the greatest authorities in these questions, assigns it, after an exhaustive analysis in his _Antiquity of Man_ (1915), to the skull with which it is found. It is, as a jaw-bone, far less human in character than the jaw of the much more ancient _Homo Heidelbergensis_, but the teeth are in some respects more like those of living men. [Illustration: DIAGRAM TO ILLUSTRATE THE RIDDLE OF THE PILTDOWN SUB-MAN.] Dr. Keith, swayed by the jaw-bone, does not think that _Eoanthropus_, in spite of its name, is a creature in the direct ancestry of man. Much less is it an intermediate form between the Heidelberg man and the Neanderthal man we shall presently describe. It was only related to the true ancestor of man as the orang is related to the chimpanzee. It was one of a number of sub-human running apes of more than ape-like intelligence, and if it was not on the line royal, it was at any rate a very close collateral. After this glimpse of a skull, the Record for very many centuries gives nothing but flint implements, which improve steadily in quality. A very characteristic form is shaped like a sole, with one flat side stricken off at one blow and the other side worked. The archæologists, as the Record continues, are presently able to distinguish scrapers, borers, knives, darts, throwing stones, and the like. Progress is now more rapid; in a few centuries the shape of the hand-axe shows distinct and recognizable improvements. And then comes quite a number of remains. The Fourth Glacial Age is rising towards its maximum. Man is taking to caves and leaving vestiges there; at Krapina in Croatia, at Neanderthal near Düsseldorf, at Spy, human remains have been found, skulls and bones of a creature that is certainly a man. Somewhere about 50,000 years ago, if not earlier, appeared _Homo Neanderthalensis_ (also called _Homo antiquus_ and _Homo primigenius_), a quite passable human being. His thumb was not quite equal in flexibility and usefulness to a human thumb, he stooped forward, and could not hold his head erect, as all living men do, he was chinless and perhaps incapable of speech, there were curious differences about the enamel and the roots of his teeth from those of all living men, he was very thick-set, he was, indeed, not quite of the human species; but there is no dispute about his attribution to the genus _Homo_. He was certainly not descended from Eoanthropus, but his jaw-bone is so like the Heidelberg jaw-bone as to make it possible that the clumsier and heavier _Homo Heidelbergensis_, a thousand centuries before him, was of his blood and race. § 5