BIOLOGICAL EVOLUTION 79 
existence of all human qualities is to be explained, if at all, on 
the assumption that they have been of value on the whole in the 
struggle for existence. 
Some modern genetic psychologists and sociologists, working 
on the above premises, and studying the behavior of animals and 
infants to get a clue to the behavior of man, have formulated the 
following conclusions which may well be included with the 
above: — 
When unconscious reactions were not adequate to survival, 
consciousness, in some cases, seems to have arisen as an adaptive 
response to this need, and having arisen, developed rapidly.! 
Every organism tends to respond positively to stimuli that 
are favorable and negatively to those that are unfavorable, and a 
favorable reaction tends to be repeated. In this way innate 
tendencies are modified and habits formed.* 
In higher organisms endowed with feeling, reactions that are 
favorable to the individual or species are accompanied, on the 
whole, by pleasurable sensations, those that are unfavorable, by 
painful sensations.* 
With the development of the human intellect giving man the 
power of selection among satisfiers of felt needs arose the possi- 
bility of a selection that was detrimental to the organism and to 
the species.‘ 
With the rise of conscious, purposeful choice, came the power of 
active adaptation, —i.e., the purposeful modification of the 
individual or group to make it better adapted to life conditions, or 
the purposeful modification of the life conditions to make them 
more favorable to the individual or group.® 
1 Ellwood, Sociology in its Psychological Aspects, p. 98. 
2 Tbid., pp. 106 f.; Thorndike, Original Nature of Man, ch. IX. 
2 Parmelee, of. cit., pp. 232 £.; Ward, Pure Sociology, p. 130: ‘‘ All pleasure is 
mandatory and all pain is monitory. ... So long as feeling and function are 
adapted pleasure means life and health and growth and multiplication, while pain 
points to danger, injury, waste, destruction, death, and race extinction.” 
4 Miller, op. cit., pp. 44 f. 
5 Ellwood, op. cit., pp. 104 f. 
