260 



HEREDITY AND VARIATION 



Some Domesticated Animals. — Our domesticated dogs are 

 descended from a number of wolflike forms in various parts of the 

 world. All the present races of cats, on the other hand, seem to 

 be traced back to Egypt. Modern horses are first noted in 

 Europe and Asia, but far older forms flourished on the earth in 

 former geologic periods. It is interesting to note that America 

 was the original home of the horse, although at the time of the 



earliest explorers the horse 

 was unknown here, the 

 wild horse of the Western 

 plains having arisen from 

 horses introduced by the 

 Spaniards. Long ages ago, 

 the first ancestors of the 

 horse were probably little 

 ^, , , . r X, X . animals about the size of 



The four-toed ancestor of the present horse, t t 



restored from a study of its fossil skeleton, a foX. The earliest horse 



(After Knight in American Museum of Nat- ^^ have knowledge of had 



ural History.) r ^ ^^ r i 



tour toes on the tore and 

 three toes on the hind foot. Thousands of years later we find a 

 larger horse, the size of a sheep, with a three-toed foot. By 

 gradual changes, caused by the tendency of the animals to vary 

 and by the action of the surroundings upon the animal in preserv- 

 ing these variations, there was eventually produced our present 

 horse, an animal with legs adapted for rapid locomotion, with 

 feet particularly fitted for the life in open fields, and with teeth 

 which serve well to seize and grind herbage. Knowledge of this 

 sort was also used by Darwin to show that constant changes in 

 the form of animals have been taking place since life began on 

 the earth. 



The horse, which for some reason disappeared in this country, 

 continued to exist in Europe, and man, emerging from his early 

 savage condition, began to make use of the animal. We know the 

 horse was domesticated in early Biblical times, and that he soon 

 became one of man's most valued servants. In more recent 

 times, man has begun to change the horse by breeding for certain 

 desired characteristics. In this manner have been established and 



