In what part of this sequence did man appear? In answer to this, I think it is now generally admitted that he is not certainly known earlier than the Post-glacial period. Various supposed indications of his presence in “Inter-glacial” Glacial, Pliocene, and even Miocene deposits have proved on examination to be unreliable. America has recently put forth claims to have been inhabited by man in the Pliocene, on the faith of remains found in auriferous gravels in the West. But the facts that the implements and bones found are modern in type, that the gravels were deeply mined by the Indians, and that the objects found, as mortars for dressing gravel, etc., are in many cases such as they would be likely to leave in their excavations, have discredited these supposed discoveries. Still more recently, chipped flints found in gravels in New Jersey, by Abbott, have been supposed to carry back the Indians of the East coast to the Glacial period. It is evident, however, from the description of these deposits by the late Mr. Belt and by Professor Cook, director of the Survey of New Jersey, that they are really Post-glacial, that their age must be estimated by study of the local conditions, and that there is no good ground for correlating them with the upper members of the true Glacial drift to the northwards, with which they had been somewhat rashly identified. Irrespective of the doubtful character of many if not all of the so-called implements, the deposits in which they are found is confessedly not a product of the ice of the Glacial period proper, whether that was, as some maintain, a period of land glaciation as far south as New Jersey or not. It belongs to a time of denudation by water, aided perhaps by floating ice, and is not necessarily older than the river gravels of the Somme, which, like it, contain boulders and imply conditions of torrential action and climate which have long since passed away. If, however, these implements are genuine, they would imply the presence of Palæocosmic or Antediluvian man in America. This would in itself be an important discovery.
For the present, therefore, man is geologically a Post-glacial species, and there is nothing unreasonable in supposing that he dates no farther back, since several animals his contemporaries are in the same case; and by supposing him to have originated after the Glacial age we avoid the difficulties attendant on his survival of that great revolution. The only necessity for supposing an earlier appearance arises from the requirements of the hypothesis of evolution. Those, however, who hold this theory, may with Haeckel take refuge in that shadowy continent supposed to have extended from Africa to Australia,[85] and to have sheltered man in his transition from the ape to humanity, in the Tertiary period. The name Lemuria is taken from the Lemurs, supposed ancestors of the Apes, which still haunt the margin of the Indian Ocean; but it may be taken also in its old Latin sense of ghosts of the evil dead; and as we are not likely to obtain any more tangible evidence of the old natives of Lemuria, perhaps we may hope that some spiritualist may succeed in charming them from the vasty deep for our enlightenment. Should this be so, it is to be hoped that no “drum ecclesiastic” will be beaten to drive them away till they have revealed all they can tell.
It may be well to add that, in addition to the negative evidence, there is at least one positive evidence of the recent origin of man which has been well urged by Le Conte. It is this: animals have continued long in geological time in the inverse ratio of their rank. Some Mesozoic protozoa still survive. So do many early Tertiary mollusks. But the mammals are of much less duration. No living species goes back farther than the Pliocene. Few extend farther than the Glacial age. On the same principle it is not to be expected that man, the highest of all animals, should extend far back in geological time.
Accepting the Post-glacial age as that of the advent of man, it may be interesting to ask what we know of the condition of our continents when he appeared. In Western Asia, in Europe, except in its more northern portions, and it would now seem also in America, man had been introduced at a time closely following the emergence of the land from the Glacial sea. At this time the land area of both continents was larger than it is at present, and the character of the fauna shows that much of the surface was occupied with great steppes or prairies, over which migration would be easy; while there were probably connections by land or chains of islands between the continents of the northern hemisphere. The land animals of the continents were more numerous and of greater stature than at present. Several species of elephants ([Fig. 186]) and a rhinoceros roamed over the plains. The formidable Elasmotherium ([Fig. 187]),[86] an animal allied to the rhinoceros, but more fleet and active, and of immense size, inhabited Asia and Europe. Hippopotami, wild horses, the gigantic Irish stag, several species of wild cattle, and bisons of greater size than their successors, haunted the streams and steppes. The cave bear, the cave lion, the spotted hyæna, and possibly the Machairodus, were among the beasts of prey even in the temperate latitudes. The climate must have been a continental one, ranging through considerable extremes; but the conditions favoured migration of animals on the great scale, so as to avoid these extremes, and hence species of types now comparatively restricted enjoyed a wide distribution.
Fig. 186.—Elephas primigenius. Post-glacial.
To establish themselves in such a world, the primitive men must have been no puny race, either in mind or body, and they must have been sheltered in some Eden of plenty and comparative safety till, by increase of numbers, invention of weapons and implements, and domestication of useful animals, they became able to cope with the monarchs of the waste. But this position once attained in the original seats of the species, the wide continents presented great facilities for their movements, and there were ample stores of food for wandering tribes subsisting by the chase.