mcgke] THE TREND OF HUMAN PROGRESS 421
pithecoid and the human types; for they warrant the inference that the lines of ascent diverged somewhere below the plane rep- resented by the modern simian. If this inference be correct, it would follow that the representatives of the human line must have either fallen in the transitional struggle or risen well into the ennobled type in long-past ages, not yet noted in the chro- nology of any continent or clearly fixed in the scale of paleon- tology. The inference and its corollary are in line with the conspicuous facts of both human and animal realms ; for the law of humanity is convergence in blood and brain to a degree over- shadowing environment, and the law of animality is divergence into varieties and species and genera adapted to environment, while no trustworthy observation suggests that even the highest apes can blend with even the lowest savages — they may be domes- ticated and indeed artificialized in some measure (though less completely than horse and dog, so far as the records go), yet there is no real interchange of culture-i-much less of blood — such as characterizes the human realm.
The testimony of function-shaped structures concerning the infancy of the race is extended by that of various vestigial func- tions and structures ; these are especially conspicuous in tree- climbing tribes, yet hardly less notable in early infancy among advanced peoples. According to Hilder, the Tagbanua tribes- man of the Philippines is almost quadrumanous; the hallux is nearly as completely opposable as the pollex, a knife or pin is readily picked up with the foot, while, in climbing, branches are grasped with the toes so firmly as to support the weight of the body ; the average Caucasian infant shares character with the Tagbanua and the bestial quadrumane to the extent of measur- ably opposable hallux and prehensile feet ; and when the heredi- tary pedal power is perpetuated by exercise, as in Unthan, the armless German (who is a fine marksman and fair penman despite his infirmity, and who uses knife and fork, or cigar and match, or comb and brush, with no less dexterity and delicacy than other
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