" ARBOREAL MAN " 229 



evolution on the part of symbiotic cross-feeders. It is not for 

 nothing that the author again instances fruits and fruit-eating 

 species. What he has to say about " change of conduct," applies 

 with special force to change of " biological " conduct, in which 

 conduct moderation and refinement of feeding habits must be 

 accorded pride of place. Very truly the author says : 



The evolution is evidently harmonious in its details. The more the 

 fore-limb becomes emancipated, the less is the hand called upon for menial 

 duties which in other stocks necessitate the development of skin thickenings, 

 pads, callosities, or hoofs. It is the freed hand which is permitted to 

 become the sensitive hand which now, so to speak, goes in advance of the 

 animal and feels its way as it climbs through life. 



The freedom referred to is virtually that which Huxley 

 appreciated, namely, that to do right, though herein the biological 

 sense. Evidently the result cannot be obtained without a 

 fairly high degree of " refinement " and restraint, without 

 commensurate biological conduct. We have discovered that 

 without a sufficiency of duly altruistic activities, the necessary 

 refinement and restraint and the very stimulus to psychical 

 progress are wanting, whilst there is wanting also the physiological 

 groundwork requisite for a high degree of plasticity of 

 the brain. Although this plasticity is a great factor in human 

 evolution, Prof. Wood Jones would not seem to have made 

 sufficient provision for it. He tells us : 



The very fact that the sense of touch becomes lodged, to so large an 

 extent, in the emancipated hand of the arboreal animal becomes a guar- 

 antee that this hand will be called upon to discharge its tactile function 

 in a variety of ways. All sorts of uses, previously quite foreign to it, will 

 be demanded of it in virtue of its possibilities as a tactile organ. The 

 combination of the increasing tactile perceptions, and the freedom of move- 

 ment, creates a condition which ultimately leads to the most important 

 developments. 



All this is quite true ; but we have found the author originating 

 the refined sense of touch (in the emancipation of the hand), with 

 the evident appeal made to the animal by the spare products 

 of the plant, namely, fruits ; and the significance of this appeal 

 is more than mechanical. 



The whole case, in fact, is but an integral part of the correlated 

 evolution of plant and animal. 



The sensory stimuli (Professor Wood Jones goes on to say), streaming 

 from the hand towards the central nervous system must become associated 

 in the most intimate way with the motor impulses streaming to the mobile 

 fingers. 



