Can behavioral evolution be measured on a staircase? A commentary.

The serious, comparative study of behavioral complexity that Greenberg et al. advocate is a progressive direction for the field, but their proposal to separate comparative psychology from its roots in evolutionary biology seems regressive. Modern evolutionary theory has been broadened within biology to include development and paleontology alongside natural selection, making closer integration with that discipline particularly timely. Such an integrated evolutionary approach in psychology would offer a useful alternative to the adaptationism popularized by evolutionary psychology. Although the differences between comparative psychologists and biologists may be blurred in the process, the behavioral sciences will be better served by a rich biological approach to evolution than by a uniquely psychological approach.