MENTAL POWERS. 91 



have lost in wariness and suspicion, yet they have pro- 

 gressed 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 describes these 

 two latter cases, attributes the victory of the common rat 

 over the large Mus coning a to its superior cunning; and 

 this latter quality may probably be attributed to the habit- 

 ual 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 possessed 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 evo- 

 lution 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, 

 somewhat like a walnut, with a stone, f Rengger J; easily 

 taught an American monkey thus to break open hard palm- 

 nuts; and afterward of its own accord it used stones to 

 open other kinds of nuts, as well as boxes. It thus also 

 removed the soft rind of fruit that had a disagreeable 

 flavor. Another monkey was taught to open the lid of a 

 large box with a stick, and afterward it used the stick as a 

 lever to move heavy bodies; and I have myself seen a young 

 orang put a stick into a crevice, slip his hand to the other 

 end, and use it in the proper manner as a lever. The 

 tamed elephants in India are well known to break off 

 branches of trees and use them to drive away the flies; and 

 this same act has been observed in an elephant in a state of 



* "Proc. Zoolog. Soc," 1864, p. 186. 



f Savage and Wvman in "Boston Journal of Nat. Hist.," vol. iv, 

 1843-44, p. 383. 



X " Saugethiere von Paraguay," 1830, s. 51-56. 



