THE FACTORS OF EVOLUTION 143 



preceded by the chase and capture of animals in the wild state. 

 At first they were probably captured without any idea of domesti- 

 cating them for the purpose of deriving certain advantages, and 

 only gradually primitive man began to perceive the uses to which 

 animals might be put. Thus there developed out of an originally 

 hostile relationship in the course of time an alliance from which 

 both parts derived advantages. Man gave to certain animals 

 shelter and food and derived in return certain services. In true 

 perception of the high value of domestic animals to civilization, 

 their treatment, with a few deplorable exceptions, has always 

 been humane ; in many countries they have even been regarded 

 with feelings of veneration and worship. 



The majority of the species of our domestic animals are very 

 old, many thousand years having elapsed since they began to 

 1 live with man/ We are, therefore, unable to judge of the pro- 

 cess of domestication by direct observation and shall be in most 

 cases referred to tradition, hypotheses, and experiments in order 

 to obtain a clear view of their history. A familiar exception is 

 the African ostrich, which has recently been thoroughly domes- 

 ticated, whilst gradually becoming extinct as a free-living bird. 

 It is, therefore, no matter of surprise that of a few domesticated 

 animals we know only their wild prototypes. Nevertheless, it 

 would be a mistake to assume that as a result of a long period 

 of domestication the wild ancestors have either become extinct 

 or have been gradually gathered up into man's stock of domesti- 

 cated animals, for research has been able to prove the existence 

 of wild ancestors in many cases where they were thought to 

 have become extinct, and it was also shown that the different 

 races of many domesticated animals, as for instance dogs, do 

 not descend from only one wild ancestor but from several. The 

 exact number of such ancestors investigation has not been able 

 to ascertain. In other cases the numerous breeds of domestic 

 animals have been traced back to one wild ancestor. 



Darwin has proved that, for instance, our domesticated 

 pigeons have all descended from the rock-pigeon (Columbia 

 livia). If we glance at the coloured plate (Plate V.) and notice 

 the sharply differentiated birds, we find it difficult to agree with 

 this statement. Nevertheless, it has been clearly proved by the 

 fact that in the crossing of widely differentiated races of pigeons, 



