MAN'S BRAIN 



499 



515. Tools and weapons. The natives of Madagascar say 

 that if a spear is thrown at a lemur, the animal will catch it 

 and throw it back with deadly precision. Monkeys will crack 

 nuts by pounding them against some hard object, and gorillas 



FIG. 260. Localization of functions in the cerebrum 



By studying human beings and other animals in which the brain had been injured, and 

 by making experiments, it has been ascertained that certain regions of the brain cortex 

 are related to receiving sensations from specific regions of the body, while other regions 

 initiate movements of specific muscles. Most of the sensory and motor nerves pass 

 through the spinal cord, SC. The thinking is carried on by the so-called association 

 areas, A-i and A-2. The frontal association area has to do with abstract thinking, self- 

 control, concentration, and making decisions. The hind association area has to do with 

 knowing and understanding concrete facts and relations 



will fight with a stick used as a club. But probably no gorilla 

 or monkey ever carried a club or a stone about with him for 

 use in possible emergencies, and that is something that man 

 has done. Even among the earliest remains of human activity 

 there are indications that man chipped stones to fit his hand, to 

 be used as weapons or perhaps for breaking shellfish (Fig. 261). 



