MENTAL EVOLUTION IN THE PRIMATES 1 25 



to which foresight leads to preparedness for a contingency. 

 All that we may safely say Is that the beginnings of foresight 

 and preadaptation are obviously discoverable In the anthro- 

 poid apes. 



To summarize, adaptation by trial and error, inslghtless 

 effort, appears In all existing types of primate and throughout 

 the course of Individual development. By contrast, adapta- 

 tion with Insight has not been discovered in the lemur or 

 tarsler, perhaps Is present In rudimentary form In the 

 monkeys, clearly manifests Itself In the man-Hke apes, and is 

 conspicuously Important in adult man. Its development 

 may be traced in the course of individual history, for whereas 

 the newborn Infant is incapable of selective adaptation, 

 the young child commonly exhibits it, and the manifestations 

 of Insight become increasingly numerous and complex as 

 the individual approaches maturity. Likewise there is 

 marked contrast from type to type and from stage to stage 

 of development In evidences of foresight and resulting pre- 

 adaptation. It appears reasonably certain that this mode of 

 behavioral adaptation does not appear in lemur, tarsier, or 

 monkey, that it is discoverable in the anthropoid apes, 

 and from this evolutional beginning becomes preeminently 

 important in adult man. Like selective adaptation. It may be 

 traced in individual development, originating during infancy 

 and becoming increasingly conspicuous through child- 

 hood and maturity. It seems Indeed as though the story of 

 our own development were traceable through the following 

 modes of adaptation or habit-formation: From the "blind 

 trial" of fetal life and infancy, through the selective adapta- 

 tions of late Infancy and childhood, with their extending 

 and enriching insights, to the foresights and preadaptations 

 of adolescence and maturity. 



If at any point our description has given the impression 

 that in either development or evolution one of these prin- 

 cipal modes of adaptation tends to replace or supplant 

 another, we should correct it, for the more primitive or 

 simpler type always, it seems, tends to persist after the 

 appearance of a psychoblologlcally more complex and more 

 efficient mode of adaptation. 



