49Q 



THE QUARTERLY REVIEW OF BIOLOGY 





He says : ' 'If it can be shown that instincts 

 do vary ever so little, then I can see no 

 difficulty in natural selection preserving 

 and continually accumulating variations 

 of instinct to any extent that was profit- 

 able. It is thus, as I believe, that all the 

 most complex and wonderful instincts 

 have originated." (zcj, 1:3x1). 



The evolution of intelligence was 

 explained on precisely the same basis — 

 variation, natural selection and heredity. 

 Darwin considered it absurd to deny a 

 low order of intelligence, including imagi- 

 nation, reason and will, to many of the 

 higher animals. He believed implicitly 

 that the mind of man with all its wealth 

 of emotional life and its moral sense had 

 developed naturally out of the mind of the 

 higher animals possessing these same 

 attributes in a rudimentary way. In The 

 Descent of Man, and in The Expression of the 

 Emotions, originally planned as a chapter of 

 this treatise, he attempted to illustrate 

 his own conception of how this develop- 

 ment had actually taken place. 



In his opinion, the conscience and the 

 moral sense constituted the greatest prac- 

 tical difference between man and the 

 higher animals. With keen insight he 

 perceived that insofar as these were 

 actually possessed by man they were the 

 natural accompaniment of his highly 

 developed intellectual and social life. 

 It seems highly probable, so he says, 

 that "any animal whatever, endowed 

 with well marked social instincts, would 

 inevitably acquire a moral sense or 

 conscience, as soon as its intellectual 

 powers had become as well developed, or 

 nearly as well developed, as in man." 

 (3 o, 1:68). 



In accounting for the development of 

 complex mental functions and moral 

 attributes Darwin applies the principle of 

 natural selection very broadly, placing 

 great emphasis upon the operation of 

 social and intellectual factors in the 



process. In a state of nature, perhaps, 

 selection may tend to the preservation of 

 one individual against another, but as 

 soon as the social instincts arise the. 

 preservation of the group becomes the 

 chief end to be attained. Utility to the 

 group, as well as mere individual strength 

 and endurance, becomes a factor in sur- 

 vival. Sympathy, mutual aid, parental 

 and filial affection, and other social 

 behavior as well as individual cunning, 

 discrimination capacity, etc., operate as 

 increasingly important determinants of 

 the course of evolution among the higher 

 animals. In man himself, the use of fire, 

 traps, tools, weapons, signs, language, 

 etc. are instances of how intelligent 

 behavior, making for group solidarity 

 and social organization, may dominate the 

 evolutionary trend. 



The anecdotal movement 



Although Darwin did not make an 

 explicit application of his theory to man 

 in the first publication of his views in The 

 Origin of Species, the point was sensed 

 immediately that man must be included in 

 any thoroughgoing evolutionary scheme. 

 The full implications of the theory, as 

 Wallace phrases them, were "that man's 

 entire nature and all his faculties, whether 

 intellectual, moral or spiritual, have been 

 derived from their rudiments in the 

 lower animals, in the same manner and 

 by the action of the same general laws 

 as his physical structure has been derived." 

 (88, page 461). Even such ardent sup- 

 porters of the theory of organic evolu- 

 tion as Huxley (59, 60) and Wallace (88) 

 did not accept completely the views of 

 Darwin, above expressed, concerning the 

 mental evolution of man. They insisted 

 that certain of the higher mental faculties, 

 and particularly the moral and spiritual 

 capacities, could not be accounted for on 

 Darwinian principles. 



The doctrine of mental evolution as 





