CONNECTING AND MISSING LINKS
sense he is a connection, but he is not a common ancestor. Heidelberg man and his lineal successor, the man of Neanderthal, constitute the first and last links of another chain whose slow change is unrecorded for three hundred and fifty thousand years. But these forms are evidently not in the line that led to modern man, although the Neanderthal type was yet alive when Man appeared on the European stage, 25,000 years ago. What lies back of our own species is still unrevealed, but we are probably out of an unknown though extremely ancient Asiatic stock. That Asia is the birthplace of humanity most authorities now agree, except the few who, because of the primitive character of the African natives and the antiquity that was Egypt, infer an African origin for the higher races. This inference seems unwarranted, for, although the negroes are primitive in most respects, in others they show a higher specialization than either the yellow or the white races. Fossil forms are now coming to light, especially in the Siwalik region of India, which could be ancestral to the great apes, and possibly to man, but one looks for the final solution of this problem farther to the north, in the comparatively unknown Asiatic plateau.
That there are gaps in our revealed record of the continuity of life—gaps due in part to incomplete exploration, in part to natural causes—is manifest; but that the record is sufficient to uphold the principle of continuity is equally manifest. Sedimentary rocks form the repository of this record, and sedimentation is always locally discontinuous because of the wearing down of the earth's surface until the force and carrying power of the streams have well nigh ceased. This wearing down of the land is followed periodically by its re-elevation through crustal movement, with consequent rejuvenation of the streams, which begin once
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