Page:Popular Science Monthly Volume 42.djvu/46

36 and beliefs; showing the effect of environment upon mental constitution, and in endless ways contributing to the natural history of human endeavor—all this abundant material has been ably canvassed, but needs to be rearranged upon a psychological basis to form the science of Anthropological Psychology.

It is so obviously impossible within the present limits to consider the facts and generalizations of these departments of science, that no justification is necessary for confining our attention to some consideration of the relations of these three paths of development to one another, and particularly to the psychological position of man. In so doing excursions into each of the fields will be made, and some glimpses be obtained of the several departments of Comparative Psychology.

To appreciate the comparison of infant with animal traits, one must bear in mind some important characteristics differentiating the young of the human kind from the young of other animals. The series of changes of which an individual life consists indicate that the individual enters life in a condition simpler than that which it eventually attains. These changes diminish in extent as we descend the scale of organisms, until in the lowest organisms the newly born and the adult are almost indistinguishable. Whether we consider the embryonic preparatory stage of life, or whether we regard as the beginning of existence the entrance to the environment of Nature, and speak of the preparatory stage as that which intervenes between birth and maturity, we shall find it measurably true that in proportion to the complexity of mental development to which the individual may eventually attain will this pre-adult period be lengthened. An aspect of this law, of special psychological interest, is the resulting difference in the powers present in the newly born of different species: the lower organism has a larger share of its powers ready at birth, has less to learn, less to be modified by and adapted to its environment than has the higher organism. Many of the marvelous instincts characteristic of the insect tribe seem to be at the service of the new-born individual. "With such creatures as the codfish, the turtle, or the fly-catcher, there is . . . nothing that can be called infancy" (Fiske). The most complete experiments bearing upon this point are those of Mr. Spalding. In the first minutes of life chickens follow "with their eyes the movements of crawling insects, turning their heads with the precision of an old fowl. In from two to fifteen minutes they pecked at some speck or insect, showing not merely an instinctive perception of distance, but an original ability to judge, to measure distance, with something like infallible accuracy." A chicken hooded as it emerged from the shell was unhooded when three days old; six minutes later "it