186 THE PRINCIPLES OF HEREDITY 



natives have been exterminated within the area of settlement. 

 It is in sharp contrast to their conquests in Asia and Africa. 

 Both in the Old World and in the New the subjugation of the 

 natives was accompanied by many wars and much bloodshed, 

 and probably the conflicts in the former were more prolonged 

 and destructive than those in the latter. But in no part of 

 the Old World have the British exterminated the natives. 

 They do not supplant them, they merely govern them. 

 Southern Asia and East and West Africa are defended by 

 malaria. The British cannot colonize them, and the natives 

 have undergone such evolution against tuberculosis, that they 

 are capable, under favourable conditions, like the American 

 slaves, of resisting the hard conditions imposed by modern 

 civilization. In South Africa, where there is little malaria, 

 Europeans share the land with the natives, but the latter are 

 likely to remain in an overwhelming majority. 



310. If history teaches any lesson with clearness it is 

 this, that conquest to be permanent must be accompanied 

 with extermination ; otherwise in the fulness of time the 

 natives expel or absorb the conquerors. The Saxon conquest 

 of England was permanent ; of the Norman conquest there 

 remains scarcely a trace. The Huns and the Franks founded 

 permanent empires in Europe ; the Roman Empire and that of 

 the Saracens in Spain soon tumbled into ruins. It is highly 

 improbable, therefore, that the British will retain their hold 

 on their Old World dependencies. A handful of aliens can- 

 not forever keep in subjugation large and increasing races 

 that yearly become more intelligent and insistant in their 

 demands for self-government. But no probable conjunction 

 of circumstances can be thought of that will uproot the 

 Anglo-Saxons from their wide possession in the New World. 

 The wars of extermination are ceasing with the spread of 

 civilization. We have ransacked the world and now know 

 every important disease. Diseases cannot come to us as 

 they came to our forefathers and to the Red Indians, like 

 visitations from on high. All the diseases that are very 

 capable of travelling have nearly reached their limits, the 

 rest we are able to check. Even in the unlikely event of a 

 new disease arising it would affect other races equally. 

 Canada and Australasia like the United States may separate 

 from the parent stem, but the race will persist. If ever a 

 New Zealander broods over the ruin of London he will be a 

 New Zealander of British descent. 



311. The Natural History of Man is, in effect, a history of 

 his evolution against disease. The story unfolded by it is 



