Il6 HUMAN BIOLOGY 



quite as strongly the observed psychobiological character- 

 istics of some other type or types of organism. The chim- 

 panzee, monkey, or in accordance with personal familiarity, 

 the horse, dog, or cat may come to mind. No longer then is 

 the picture distinctively and unmistakably human. "Why, 

 it might perfectly well be some other kind of being," exclaims 

 the amazed onlooker. 



And now as the record continues to unroll, surprises 

 crowd one another, for the suggestion or definite appearance 

 of the behavioral and mental characteristics of other types of 

 animal than the human become more insistent, and doubt 

 as to whether the record really represents human develop- 

 ment gives place to the conviction that one is being deceived 

 and that the picture really represents some stage in the 

 psychobiological development of a yet more lowly and 

 primitive mammal than the chimpanzee, monkey, or even 

 the lemur. Presently perhaps the behavior of the fish is so 

 definitely suggested that the observer again utters exclama- 

 tions of amazement and increduhty. 



Although such a pictorial record as we imagine never 

 has been made and could be obtained only with extreme 

 difficulty, it is not impossible. Were one to observe, instead 

 of our hypothetical record of mental development, a chrono- 

 logically comparable record of the development of the body, 

 the eff'ect on the lay observer would be very similar. No 

 description of the evolution of the human mind known to 

 us is more incredible, more difficult to understand as natural 

 process, or more at variance with certain well-estabfished 

 social traditions, including befiefs and superstitions, than 

 is the actually observable series of events between the 

 fertihzation of the ovum and the maturation of the human 

 personahty. 



Among the preconceptions, superstitions, or inadequately 

 founded befiefs which we should brush aside in order fairly 

 and profitably to examine the evidences of genetic relation 

 among different types and conditions of mind, is the assump- 

 tion that man possesses rational intelfigence, whereas other 

 animals are endowed with instinct. Critical and sustained 

 study of animal behavior indicates on the contrary that 

 although among existing primates man is the reasoner par 



