Then there are the more complex original tendencies such as sucking, chewing, sitting up, and gurgling. Among the more general unlearned responses of children are fear, anger, pugnacity, envy, jealousy, curiosity, constructiveness, love of festivities, ceremonies and ordeals, sociability and shyness, secretiveness, etc. Thorndike, who quotes this list at length, has sought to give definiteness to its descriptions by clearly defining and distinguishing the character of the situation to which the behavior cited is a response. For example, to the situation, "strange man or animal, to solitude, black things, dark places, holes and corners, a human corpse," the native and unlearned response is fear. The original response of man to being alone is an experience of discomfort, to perceiving a crowd, "a tendency to join them and do what they are doing and an unwillingness to leave off and go home." It is part of man's original nature when he is in love to conceal his love affairs, and so forth.
It is evident from this list that what is meant by original nature is not confined to the behavior which manifests itself at birth, but includes man's spontaneous and unlearned responses to situations as they arise in the experience of the individual.
The widespread interest in the study of children has inspired in recent years a considerable literature bearing upon the original and inherited tendencies of human nature. The difficulty of distinguishing between what is original and what is acquired among the forms of behavior reported upon, and the further difficulty of obtaining accurate descriptions of the situations to which the behavior described was a response, has made much of this literature of doubtful value for scientific purposes. These studies have, nevertheless, contributed to a radical change in our conceptions of human nature. They have shown that the distinction between the mind of man and that of the lower animals is not so wide nor so profound as was once supposed. They have emphasized the fact that human nature rests on animal nature, and the transition from one to the other, in spite of the contrast in their separate achievements, has been made by imperceptible gradations. In the same way they have revealed, beneath differences in culture and individual achievement, the outlines of a pervasive and relatively unchanging human nature in which all races and individuals have a common share.