The possibility of comparative cognitive science in fish from the view of behavioral ethology

Abstract

The field of comparative cognitive science has focused especially on mammals and some birds because of their phylogenetic closeness with humans and their larger brain compared to "lower vertebrates" such as fish. However, recent comparative analyses and conceptual models in the field of animal psychology and/or animal behavior propose that cognitive abilities have evolved in response to ecological and/or social factors. In addition, it has been shown that brain organization are largely conserved throughout the vertebrates, suggesting that lower vertebrates may have more sophisticated cognitive abilities than previously thought. Therefore, to reveal the phylogenetic distribution of cognitive abilities we should also examine lower vertebrates. In fact, ethologists have demonstrated diversity of social and ecological complexities in fish, which are good candidate for helping to reveal how cognitive abilities evolved. Therefore, I focus on fish cognition in this review. Recent studies have shown that some fish behave depending on the types of information they receive. As examples, I introduce studies about flexible decision-making and social cognitive abilities in cichlid fish in Lake Tanganyika, and cleaner wrasse. Finally, I discuss the evolution of cognitive abilities in different ecological contexts.