The comparative psychology of marsupials

Outdated views on behavioural evolution held that marsupials should be less "smart" than standard laboratory mammals. Changing attitudes, based on ecological, physiological, and phylogenetic considerations, led to the conclusion that marsupial mammals represent an alternative rather than an inferior mammalian design. We review the available research on marsupial psychology and conclude that the most studied marsupial, the American opossum, may be one of the most successful nonhuman animals ever tested on many standard psychological tasks. The traditional eutherian bias in psychological research on mammals has resulted in most of the few analyses of marsupials being conducted as comparative sidelines to eutherian research. However, the two evolutionary radiations of marsupials (in the Americas, and in Australia) represent a natural experiment that offers great potential for comparative analysis of the relationship between ecological pressures and psychological skills.