The Development of Sensorimotor Cognition in Common Ravens (Corvus corax) and its Comparative Evolution

Abstract

Citation-Jacobs, I., Kabadayi, C., & Osvath, M. (2019). The development of sensorimotor cognition in common ravens (Corvus corax) and its comparative evolution. Animal Behavior and Cognition, 6(3), 194-212. https://doi. Abstract-Evolution involves developmental change. Species comparisons play an important role in comparative cognition because they can uncover common patterns and shared principles in cognitive evolution. Developmental studies reveal foundational elements of cognitive abilities and how they are constructed and integrated. Sensorimotor cognition is such a key element that forms the foundation for later-developing cognitive skills, yet little is known about its development in animals. This study uses 37 behaviors and tasks to investigate the development of Piagetian sensorimotor abilities in five young ravens (Corvus corax) from ages two to eleven weeks. Their developmental pattern largely mirrored that of twelve other bird and mammal species, albeit at a markedly accelerated rate. They reached the final sensorimotor stage, which to date has been shown only in great apes. The onset and sequence of sensorimotor development was identical for all species. Absolute number of neurons in the pallium and rest of brain was associated with achieving a higher stage across these species. This was not the case for absolute or relative brain mass, or number of neurons in the cerebellum or whole brain. We discuss the independent evolution of sensorimotor cognition and the importance of developmental pace and pattern therein. These findings show that the study of sensorimotor development is a useful tool for comparative cognition research. A major challenge in comparative psychology lies in making reliable comparisons among species, which becomes particularly difficult when they differ in such respects as morphology and ecology. These challenges become more pronounced with the discovery of complex cognition in taxa phylogenetically distant from one another. However, studying development may reveal how fully functional cognitive abilities are composed of diverse elements and their interactions, which different taxa share to various degrees. Developmental studies are thus an important tool in comparative cognition. To date, however, relatively little research has been done on cognitive development across species. Tinbergen (1963) added ontogeny (development) to the other three major questions one must answer to get a complete understanding of a behavior: causation (mechanism), survival value (fitness), and evolution (phylogeny). Respectively, these questions ask how a behavior develops, how it works, what it evolved for, and how it evolved. All four questions are rarely answered, and the developmental perspective is especially lagging behind (Bateson & Laland, 2013). The development of human cognition has been a fruitful research area for a long time-with Darwin's (1877) study of his own children as a notable early example-but less is known about cognitive development in other species, despite the fact that it also evoked interest in the early days of comparative cognition (e.g., Mills, 1898; Morgan, 1896).