200 MENTAL EVOLUTION IN ANIMALS. 



CHAPTEE XIII. 



Instinct (contimced). 



Blended Origin, or Plasticity of Instinct. 



From the foregoing discussion it may, I think, be taken as 

 established : — 



1st. That propensities or habitual actions may originate 

 and be inherited without education from parents or other- 

 wise, as in the case of " tricks of manner," peculiar disposi- 

 tions, tumbling of tumbler pigeons, &c. ; in such cases there 

 need be no intelligence concerned in the propensity or action, 

 but if such propensities or actions occur in nature (and, as we 

 have seen, there can be no doubt that they do), those which 

 happen to be of benefit to the animals performing them, will 

 be fixed and improved by natural selection ; when thus fixed 

 and improved they constitute what I have called instincts of 

 the primary class. 



2nd. That adjustments originally intelligent may by 

 frequent repetition become automatic, both in the individual 

 and in the race ; as instances of such " lapsed intelligence " 

 in the individual I have given the highly co-ordinated and 

 laboriously acquired actions of walking, speaking, and 

 others ; as instances of the same thing m the race I have 

 dwelt on the hereditary character of handwriting, artistic 

 talent, &c., and in the case of animals, on peculiar habits — 

 such as grinning in dogs, begging in cats — being transmitted 

 to progeny, as well as the more instructive facts with regard 

 to the loss of wildness by certain domesticated animals, and 

 the gradual acquisition of this instinct by animals inhabiting 

 islands previously unfrequented by man. All these and 

 other such cases have been chosen as illustrations, because in 

 none of them can the principle of selection have operated in 

 any considerable degree. 



