8 MAN THE ANIMAL 



by doubling or repeated redoubling, in short. He then concluded 

 that the reason for this progression by doubling of the brain 

 volume was to be found in "the natural property of (most) 

 living beings or tissues to grow by bipartition of cells. It is thus 

 that the number of nerve cells increases and brings about the 

 progression of brain organization." The most interesting thing 

 about this progression is its discontinuity — its doubling jumps — 

 if the results and deductions of Dubois be accepted at their face 

 value. Brain volume, and inferentially mental capacity, have 

 not progressed evolutionally to their present pinnacle in man 

 by gradual travel up a smooth ramp, but rather by climbing a 

 flight of stairs in which each riser is twice as high as the one 

 next below it. When we come near to the top of the stairs 

 Dubois finds, as already mentioned, that there are two degrees 

 of difference instead of one between the existing anthro- 

 pomorphous great apes and man in respect of encephalization. 

 One step in the old staircase is left out. That missing step Dubois 

 triumphantly assigns to Pithecanthropus ^ whose coefficient of 

 encephalization he figures out to be "exactly double that of the 

 anthropomorphous apes, and exactly half the human coefficient." 

 Insofar then, but only insofar, the Trinil ape-man may be 

 regarded as the "missing link." 



All this makes a fascinatingly interesting story, and whether 

 or not it be fully accepted at the valuation attached to it by 

 Dubois, it is based upon long, patient, and, in the best scientific 

 sense of the word, imaginative research. It almost compels 

 speculation about a theoretically possible, even though long 

 distant future. Suppose it to be the case that the evolutionary 

 process has not yet ended for all eternity with man. And suppose 

 further that man is able to survive as a species for a sufficiently 

 long further period so that a gene mutation or alteration occurs 

 of such sort as to lead the nerve cells of the brain each to make 

 one more division than is now the case before ceasing to divide 

 at all. Then, provided this hypothetical mutation did not alter 

 the dividing behavior of any other cells of the body except 

 those of the brain, the world would find itself possessed of a 



