232 ORIGIN OF SPECIES 



acquired a long neck' and lofty stature, besides the giraffe, 

 and, in lesser degree, the camel, guanaco, and macrauchenia ? 

 Or, again, why has not any member of the group acquired a 

 long proboscis? With respect to S. Africa, which was for- 

 merly inhabited by numerous herds of the giraffe, the answer 

 is not difficult, and can best be given by an illustration. In 

 every meadow in England in which trees grow, we see the 

 lower branches trimmed or planed to an exact level by the 

 browsing of the horses or cattle ; and what advantage would 

 it be, for instance, to sheep, if kept there, to acquire slightly 

 longer necks? In every district some one kind of animal 

 will almost certainly be able to browse higher than the 

 others; and it is almost equally certain that this one kind 

 alone could have its neck elongated for this purpose, through 

 natural selection and the effects of increased use. In S. 

 Africa the competition for browsing on the higher branches 

 of the acacias and other trees must be between giraffe and 

 giraffe, and not with the other ungulate animals. 



Why, in other quarters of the world, various animals be- 

 longing to this same order have not acquired either an 

 elongated neck or a proboscis, cannot be distinctly answered; 

 but it is as unreasonable to expect a distinct answer to such 

 a question, as why some event in the history of mankind did 

 not occur in one country, whilst it did in another. We are 

 ignorant with respect to the conditions which determine the 

 numbers and range of each species ; and we cannot even con- 

 jecture what changes of structure would be favourable to 

 its increase in some new country. We can, however, see in a 

 general manner that various causes might have interfered 

 with the development of a long neck or proboscis. To reach 

 the foliage of a considerable height (without climbing, for 

 which hoofed animals are singularly ill-constructed) implies 

 greatly increased bulk of body ; and we know that some areas 

 support singxilarly few large quadrupeds, for instance S. 

 America, though it is so luxuriant; whilst S. Africa abounds 

 with them to an unparalleled degree. Why this should be 

 so, we do not know; nor why the later tertiary periods should 

 have been much more favourable for their existence than the 

 present time. Whatever the causes may have been, we can 

 see that certain districts and times would have been much 



