The human species must have made a beginning like the Aryans. Upon leaving their centre of creation, it was by slow stages, that the primitive colonists, ancestors of all existing races, marched forth to the conquest of the uninhabited world. They thus accustomed themselves to the different conditions of existence imposed upon them by the north, the south, the east, or the west, cold or heat, plain or mountain. Diverging in every direction, and meeting with different conditions of life, they gradually established a harmony between themselves and each one of them. Thus acclimatisation, advancing at the same rate as geographical conquest, was less fatal. The struggle, however, though mitigated indeed by the slowness of the advance, still existed, and many pioneers must have fallen upon the route. But the survivors had only nature to face, and, therefore, succeeded, and peopled the world. BOOK VII. PRIMITIVE MAN.—FORMATION OF THE HUMAN RACES. CHAPTER XXI. PRIMITIVE MAN. I. The primitive type of the human species must necessarily have been effaced, and have disappeared. The enforced migrations, and the actions of climate, must of themselves have produced this result. Man has passed through two geological epochs; perhaps his centre of appearance is no longer in existence; at any rate, the conditions are very different to those prevailing when humanity began its existence. When everything was changing round him, man could not avoid being changed also. Crossing, also, has certainly played its part in this transformation. I shall shortly return to these different points which I only allude to here. But, on the other hand, we shall see that the skull of the most ancient Quaternary race is repeated not only in some Australian tribes, but in Europe, and in men who have played an important part among their fellow-countrymen. The other races of the same epoch, judging from the skull, have many representatives amongst us. They have, nevertheless, passed through one of the two geological revolutions, which separates us from our original stock. It is then not impossible that the latter may have transmitted to a certain number of men, perhaps scattered in time and space, at least a part of its characters. Unfortunately, we do not know where to seek for reproductions, bearing more or less resemblance to the primitive type; and, for want of information it would be impossible to recognise them as such, if we were to meet with them. Here, therefore, observation alone can furnish no data. But, when it is aided by physiology, some conjectures are possible.