It is not clear why iron should not have been the earliest metal to be used by man, but the Iron Age dates from about the middle of the second millennium B.C. From Egypt the usage spread through the Mediterranean region to North Europe, or it may have been that discoveries made in Central Europe, so rich in iron-mines, saturated southwards, following for instance, the route of the amber trade from the Baltic. Compared with stone, the metals afforded much greater possibilities of implements, instruments, and weapons, and their discovery and usage had undoubtedly great influence on the Ascent of Man. Occasionally, however, on his descent. Retrospect Looking backwards, we discern the following stages: (1) The setting apart of a Primate stock, marked off from other mammals by a tendency to big brains, a free hand, gregariousness, and good-humoured talkativeness. (2) The divergence of marmosets and New World monkeys and Old World monkeys, leaving a stock--an anthropoid stock--common to the present-day and extinct apes and to mankind. (3) From this common stock the Anthropoid apes diverged, far from ignoble creatures, and a humanoid stock was set apart. (4) From the latter (we follow Sir Arthur Keith and other authorities) there arose what may be called, without disparagement, tentative or experimental men, indicated by Pithecanthropus "the Erect," the Heidelberg man, the Neanderthalers, and, best of all, the early men of the Sussex Weald--hinted at by the Piltdown skull. It matters little whether particular items are corroborated or disproved--e.g. whether the Heidelberg man came before or after the Neanderthalers--the general trend of evolution remains clear. (5) In any case, the result was the evolution of _Homo sapiens, the man we are_--a quite different fellow from the Neanderthaler. (6) Then arose various stocks of primitive men, proving everything and holding fast to that which is good. There were the Palaeolithic peoples, with rude stone implements, a strong vigorous race, but probably, in most cases, supplanted by fresh experiments. These may have arisen as shoots from the growing point of the old race, or as a fresh offshoot from more generalised members at a lower level. This is the eternal possible victory alike of aristocracy and democracy. (7) Palaeolithic men were involved in the succession of four Great Ice Ages or Glaciations, and it may be that the human race owes much to the alternation of hard times and easy times--glacial and interglacial. When the ice-fields cleared off Neolithic man had his innings. (8) And we have closed the story, in the meantime, with the Metal Ages. [Illustration: _After the restoration modelled by J. H. McGregor._ PILTDOWN MAN, PRECEDING NEANDERTHAL MAN, PERHAPS 100,000 TO 150,000 YEARS AGO] [Illustration: _After the restoration modelled by J. H. McGregor._ THE NEANDERTHAL MAN OF LA CHAPELLE-AUX-SAINTS