AND PERSONALITY 



As man's brain evolved, he bred those horses that had 

 the greatest endurance, speed, and courage and that could 

 best meet with the vicissitudes of food and climate. Even 

 at that early day man must have glimpsed the principle of 

 inheritance. He must have noticed that the horses of highest 

 speed reproduced their kind and that slow and inefficient 

 horses reproduced their kind. Thus the advance of the brain 

 of man carried with it the advance of the speed and endur- 

 ance of the horse. 



It would naturally follow that the greater advance of the 

 horse would occur among the people who depended most 

 completely on it, in particular those who represented high 

 intelligence. This would be among the desert people who 

 had to fight for the water hole and travel long distances for 

 pasture. The desert belt runs across North Africa and 

 Arabia, the domain of the Barbs, the Arabs, and the Turks. 

 It is here that the horse was advanced by natural selection 

 and breeding. The fertile plains and valleys of the far 

 north could not have produced as much human need 

 for the highly developed horse as was provided by the 

 desert. 



Thus, with the rise of man came the rise of the horse, 

 until finally the desert-bred stallions were transported to 

 the British Isles. Here they were bred with native mares 

 whose brains, hearts, blood volume, and thyroid glands 

 through the influence of the cold, blustering northern 

 climate, had been advanced in size. 



Dr. W. J. Stewart McKay, in his study of the thorough- 

 bred, cites evidence that the thoroughbred horse owed an 

 important debt to the native English mares. 



The Shetland pony is an example of a horse whose 

 energy system has been modified by cold. The ratio of the 

 weight of the brain and the thyroid gland to the body 

 weight of a Shetland pony that we collected was 1:294; 

 the ratio of the weight of the brain and thyroid gland to the 

 body weight of Equipoise, the famous thoroughbred, was 



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