EVOLUTION OF MAN SMITH. 567 



in acquiring this fuller appreciation of the meaning of events taking 

 place around the animal '? The state of consciousness awakened by a 

 simple sensory stimulation is not merely an appreciation of the 

 physical })roperties of the object that suppUes the stimulus; the 

 object simply serves to bring to consciousness the results of experience 

 of similar or contrasted stimulations in the past, as well as the feehngs 

 aroused by or associated with them, and the acts such feelings excited. 

 This mental eni-ichment of a mere sensation so that it acquires a very 

 precise and complex meaning is possible only because the individual 

 has tliis extensive experience to fall back upon; and the faculty of 

 acquirmg such experience applies the possession of large neopaUial 

 areas for recording, so to speak, these sensation factors and the 

 feehngs associated with them. The "meaning" which each creature 

 can attach to a sensory impression presumably depends, not on its 

 experience only, but more especially upon the neopalhal provision in 

 its brain for recording the fruits of such experience. 



Judged by this standard, the human brain bears ample witness, in 

 the expansion of the great temp oro -parietal area, which so obviously 

 has been evolved from the regions into which visual, auditory, and 

 tactile impulses are poured, to the perfection of the physical counter- 

 part of the enrichment of mental structure, which is the fundamental 

 characteristic of the human mind. 



The second factor that came into operation in the evolution of the 

 human brain is merely the culmination of a process wliich has been 

 steadily advancing throughout the primates. I refer to the high 

 state of perfection of the cortical regulation of sldlled movements, 

 many of which are acquired by each individual in response to a com- 

 peUing instinct that forces every normal human being to work out 

 his own salvation by perpetually striving to acquire such manual 

 dexterity. 



This brings us to the consideration of the nature of the factors that 

 have led to the wide differentiation of man from the goriUa. Why is 

 it that these two primates, structurally so similar and derived simul- 

 taneously from common parents, should have become separated by 

 such an enormous chasm, so far as their mental abihtics are concerned ? 



There can })c iio doubt that this process of differentiation is of the 

 same nature as those which led one branch of the Eocene tareioids 

 to become monkeys while the other remained prosimise; advanced 

 one gi'oup of primitive monkeys to the catarrhine status, while the 

 rest remained platyrrhine; and converted one division of the Old 

 World apes into anthropoids, while the others retained their old 

 status. Put into this form as an obvious truism, the conclusion is 

 suggested that the changes which have taken place in the brain to 

 convert an ape into man are of the same nature as, and may be 

 looked upon merely as a continuation of, those processes of evolution 



