Behavior: An Introduction to Comparative Psychology

upon them. On the other hand, one cannot for a moment assume that the Paramecium responds to light ; that the rat learns a problem more quickly by working at the task five times a day than once a day, or that the human child exhibits plateaux in his learning curves. These are questions which vitally concern behavior and which must be decided by direct observation under experimental conditions. This attempt to reason by analogy from human conscious processes to the conscious processes in animals, and vice versa, to make consciousness, as the human being knows it, the center of reference of all behavior, forces us into a position similar to that which existed in biology in Darwin's time. The whole Darwinian movement was judged by the bearing it had upon the origin and development of the human race. Expeditions were undertaken to collect material which would establish the position that the rise of the human race was a perfectly natural phenomenon and not an act of special creation. Variations were carefully noted and along with them the evidence that they might be heaped up along lines which would be of service to the animal ; for in this and the other Darwinian mechanisms were to be found factors sufficiently complex to account for the origin and race differentiation of man. The wealth of material collected at this time was considered valuable largely in so far as it tended to develop the concept of evolution in man. It is strange that this situation should have remained the dominant one in biology for so many years. The moment zoology undertook the experimental study of evolution and descent, the situation immediately changed. Man ceased to be the center of