78 THE DESCENT OF MAN. 



first set up in any district, many birds kill themselves by flying 

 against the wires, but that in the course of a very few years they 

 learn to avoid this danger, by seeing, as it would appear, their 

 comrades killed.^- 



If we look to successive generations, or to the race, there is no 

 doubt that birds and other animals gradually both acquire and 

 lose caution in relation to man or other enemies ;=» and this 

 caution is certainly In chief part an inherited habit or instinct, 

 but in part the result of individual expei'ience. A good observer, 

 Leroy,'* states, that in districts where foxes are much hunted, 

 the young, on first leaving their burrows, are incontestably much 

 more wary than the old ones in districts where they are not much 

 disturbed. 



Our domestic dogs are descended from wolves and jackals,^^ 

 and though they may not have gained in cunning, and may have 

 lost in wariness and suspicion, yet they have progressed in 

 certain moral qualities, such as in affection, trust-worthiness, 

 temper, and probably in general intelligence. The common rat has 

 conquered and beaten several other species throughout Europe, 

 in parts of North America, New Zealand, and recently in Formosa, 

 as well as on the mainland of China. Mr. Swinhoe,^" who de- 

 scribes these two latter cases, attributes the victory of the com- 

 mon rat over the large Mus cominga to Its superior cunning; and 

 this latter quality may probably be attributed to the habitual 

 exercise of all its faculties in avoiding extirpation by man, as 

 well as to nearly all the less cunning or weak-minded rats having 

 been continuously destroyed by him. It is, however, possible that 

 the success of the common rat may be due to its having pos- 

 sessed greater cunning than its fellow-species, before it became 

 associated with man. To maintain, independently of any direct 

 evidence, that no animal during the course of ages has progressed 

 in intellect or other mental faculties, is to beg the question of 

 the evolution of species. We have seen that, according to Lartet, 

 existing mammals belonging to several orders have larger brains 

 than their ancient tertiary prototypes. 



It has often been said that no animal uses any tool; but 

 the chimpanzee in a state of nature cracks a native fruit, some- 



32 For additional evidence, with details, see M. Houzeau, 'Les Facultes 

 Mentales,' torn. ii. 1872, p. 147. 



23 See, with respect to birds on oceanic islands, my 'Journal of Re- 

 searches during the voyage of the "Beag-Ie" ' 1845, p. 398. 'Origin of 

 Species," 5th edit. p. 260. 



3* 'Lettres Phil, sur I'Intelligence des Animaux,' nouvellt edit. 1S02, 

 p. 86. 



"= See the evidence on this head in chap. i. vol. 1. 'On the Variation 

 of Animals and Plants under Domestication.' 



3» 'Proc. Zoolog. Soc' 1864, p. 186. 



