The Janus-faced nature of comparative psychology--strength or weakness?

What is the nature of comparative psychology and how does or should it relate to evolutionary psychology? This is a time of reassessment of both fields and this article reviews the history of comparative psychology and its relationships with evolutionary psychology, ethology, and other approaches to behavior from the perspective of a former editor of the Journal of Comparative Psychology who has spent many decades engaged in research in animal behavior. Special attention is given to a reassessment of comparative psychology that was carried out in 1987. The various tensions and orientations that seem endemic to comparative psychology may, in fact, be both a strength and weakness as comparative psychology and evolutionary approaches to human psychology return to issues prominent in the late 19th Century, when both fields were just becoming established.