19. THE PRIMATES 



IN THE primates and, particularly, in anthropoid apes, one 

 might expect to find the pattern of the human being 

 with respect to the relative size of the brain and the thyroid 

 and adrenal glands. We found in the 536 primates that we 

 dissected a larger ratio of brain to body weight than in any 

 other wild or domestic animal of comparable size, but the 

 ratio of the thyroid to adrenal glands in the primates other 

 than man did not follow the relation of the thyroid to 

 adrenal glands in man. 



The primates in the wild state in their tree life require an 

 energy mobilization exactly the opposite to that of walking, 

 thinking man. The surface area of the primates, with their 

 long arms and legs, endows them with exceptional facilities 

 for eliminating the internal heat resulting from their 

 extreme activity. 



One has only to consider the stealthy, tree-climbing 

 leopard, the enemy of the primates, to realize that if the 

 primates had the thyroid-adrenal equation possessed by 

 man they would be more intelligent but too slow to escape 

 the leopard. In such a dramatic existence, primates having 

 the energy pattern of walking, thinking man, with his 

 large thyroid gland, and small adrenal glands, would have 

 left no progeny. 



The physical prowess of the gorilla is overwhelmingly 

 superior to that of man and other primates, possibly even 

 to that of the lion. The size of the brain of the gorilla, the 

 degree of his intelligence, the fact that he can walk upright 

 and is a ferocious caricature of man, and the further fact 

 that the adrenal glands of the gorilla have been estimated 

 to be five times as large as the thyroid gland the formula 

 of the adrenal-thyroid relation of the human fetus suggest 

 the apelike ancestor of man. 



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