into consideration, we concluded that the differentiation of the human species took place during tertiary times. Reasoning in like manner from the geographical situation of the discovery, we may suppose Indo-Malaysia to have been the cradle-land of mankind. The assumption is further substantiated by the fact that this tropical region is still the home of many of the higher apes, and was probably the point of departure for the dispersion of the other anthropoids. If we turn, now, to the evidences of quaternary culture we shall find a multitude of human relics buried in the pleistocene or post-pleistocene deposits of every continent of the globe. The widespread diffusion of these remains proves beyond peradventure the existence of man in every quarter of the earth at the beginning of the prehistoric epoch. Obviously, then, the descendants of the pliocene precursor must have wandered far and wide from the original abode during the long geological era that elapsed between the pliocene and post-pleistocene periods. It is incumbent on us, therefore, to determine how this migratory movement was effected. Close upon the problem of the differentiation of the human species comes, in other words, that of the dispersion of mankind over the face of the earth.
Subjectively speaking, there were evidently no difficulties in the way. The human prototype was, as we know, structurally fitted to walk, and his omnivorous manner of life must in itself have led him further and further forth in search of subsistence. In so far as physical capacity and psychic motive are concerned we may, therefore, think of the pliocene precursor as an ambulatory, omnivagant animal. It is only when objective conditions are taken into account that obstacles appear to arise. Granting primeval man's ability and desire to wander, how are we to imagine he endured the vicissitudes of climate that met him on the march? and how are we to suppose he crossed the seas that separate the several continents? Before the great antiquity of the human race was assured, it was necessary to assume an almost miraculous power of adaptation on man's part, and furthermore to endow him, somewhat inconsequently, with an innate knowledge of navigation; but now that science has succeeded in tracing man's ancestry back to tertiary times, we may more logically accept the explanation that geology affords. Instead of proceeding upon the presumption that the climate and configuration of the earth was then as it is now, we must reckon with the geological changes that have since occurred and work out our conclusions accordingly. In so doing we shall find that during these early ages of his existence on earth, environmental influences opposed no insuperable barriers before the dispersive propensities of man.
If, as we have supposed, the prototype was differentiated from the apes in Indo-Malaysia during the pliocene period, and arrived in re-
