236 THE DESCENT OF MAN. Part I. 



ing the varying offspring ; but most of our races have 

 been formed, not intentionally from a selected pair, 

 but unconsciously by the preservation of many indi- 

 viduals which have varied, however slightly, in some 

 useful or desired manner. If in one country stronger 

 and heavier horses, and in another country lighter and 

 fleeter horses, were habitually preferred, we may feel 

 sure that two distinct sub-breeds would, in the course 

 of time, be produced, without any particular pairs 

 or individuals having been separated and bred from 

 in either country. Many races have been thus formed, 

 and their manner of formation is closely analogous with 

 that of natural species. We know, also, that the 

 horses which have been brought to the Falkland 

 Islands have become, during successive generations, 

 smaller and weaker, whilst those which have run wild 

 on the Pampas have acquired larger and coarser 

 heads; and such changes are manifestly due, not to 

 any one pair, but to all the individuals having been 

 subjected to the same conditions, aided, perhaps, by 

 the principle of reversion. The new sub-breeds in 

 none of these cases are descended from any single 

 pair, but from many individuals which have varied in 

 different degrees, but in the same general manner; 

 and we may conclude that the races of man have been 

 similarly produced, the modifications being either the 

 direct result of exposure to different conditions, or the 

 indirect result of some form of selection. But to this 

 latter subject we shall presently return. 



On the Extinction of the Races of Man. — The partial 

 and complete extinction of many races and sub-races 

 of man are historically known events. Humboldt saw 

 in South America a parrot which was the sole living 

 creature that could speak the language of a lost tribe. 



