776 MAN 



developmental incentive, first choice would seem to fall most naturalK^ to 

 the specialized structure of the body best adapted to externalize the neural 

 energies of the brain. Such a flexible instrument as the human hand seems 

 preeminently fitted for these purposes. \\ ith the brain to direct its action, 

 to expand its usefulness, the upright posture to give freer range to its execu- 

 tion, with speech to make its accompfishments communal, to introduce the 

 benefits of cooperation, the hand became the master key opening all of the 

 ways leading through the new and vast domain of human behavior. 



