Ecological Significance of Imprinting and Early Learning

Recent years have seen a considerable expansion in the study of imprinting, both in the groups of animals studied and the motivational systems and the kinds of problems involved. Whereas early work on imprinting was restricted almost entirely to birds, some recent investigations have also been carried out with insects, fish, and mammals. And whereas the early findings referred only to the acquisition of object preferences in the social sphere, studies in the meantime have been extended to a wide variety of other behavioral characters (5, 40). Moreover, apart from collecting further data about the various aspects of the phenomenon of imprinting itself, research now also covers the physiological background of the imprinting process, e.g. its possible relationships with the maturation of sensory organs and pathways (8, 74), with brain maturation (49, 86), with biochemical changes in the brain (7, 37, 83), and with the maturation of hormonal systems (50). Finally, it is being realized more and more that imprinting may also be of considerable ecological and evolutionary significance. It is this aspect that has found increasing attention during recent years and that seems to justify a review in a series mainly devoted to the field of ecology.