VARIATION IN DOMESTIC ANIMALS 461 



now represented by the Mongolian or Prejvalsky horse, was a fleet, 

 active horse of about 13 hands height, perhaps most distinctively 

 characterized by its large head and Roman nose. The modern Shire and 

 Clydesdale exh : bit this type of head, and evidently trace along one line 

 to steppe ancestors, as do other Roman-nosed breeds. The Siwalik horse 

 of India was a tall finely built horse of racing type. Horses of this type 

 may have been over 15 hands high, and they had a peculiar promi- 

 nence between the eyes which is still met with among some Arabian and 

 Indian horses. Some Thoroughbreds today exhibit characters which 

 connect them with ancestors of the Siwalik type. The evidence, there- 

 fore, is very strongly in support of the belief in the polyphyletic origin 

 of modern breeds of horses. In the characters of these ancient ancestors 

 of the horse we may find represented practically all the characters of 

 modern horses. 



In historic times there is abundant evidence that mixing of distinct 

 types of horses was a very common practice. In Europe the fleet, finely 

 built horses of the Oriental desert type, particularly the Arab and the 

 Barb, have been used freely in perfecting practically all modern breeds 

 of horses. At about the beginning of the 18th Century, three Ori- 

 ental stallions, the Godolphin Barb, the Byerly Turk, and the Barley 

 Arabian were used extensively in England, and from this foundation 

 stock sprang the Thoroughbred and Hackney, and later in America the 

 Standard bred. As late as 1820 two gray Arabian horses Godolphin and 

 Gallipoli were used on draft mares in La Perche, and they had a remark- 

 able influence in the direction of superior quality and action in Percheron 

 horses. And this is only one side of the story of diversity in the founda- 

 tion stock of modern breeds of horses, for without exception they all have 

 a comparatively short history of strict matings confined to the breed 

 standards. 



The horse has been chosen merely as an example; other kinds of 

 livestock show just as striking ancestral diversity. Among cattle there 

 is evidence of zebu ancestry in some breeds like the Shorthorn, whereas 

 the Aberdeen-Angus seems to trace to an ancient Syrian race. As in 

 horses so in cattle there has been much mixing of types within historical 

 times. In the case of the domestic fowl, the opinion is usually defended 

 that there is evidence of monophyletic origin, the wild jungle fowl, 

 Gallus bankiva being regarded as the common ancestor. But there is 

 evidence that the Malay breeds have descended from another species, 

 and in view of the freedom with which the Malay breeds cross with other 

 breeds of fowl, it may be wise to reserve judgment of the monophyletic 

 origin of barnyard fowls. It is, however, proper to state that many of 

 the breeds of fowls do show differences which are of the value of simple 

 factor differences, or recombinations of a few such original differences; 



