This book focuses on sensing and the evolution of animals. Using the five senses (visual, auditory, and olfactory perception, and taste and touch), animals can receive environmental stimuli and respond to them. Changes in these sensitivities might cause changes in aspects of animals' lives such as habitat, activity timing, and diet-and vice versa. Recent advances in genome and molecular analysis enable us to investigate certain changes in the receptors or mechanisms involved in sensing and provide clues for understanding the evolution of animals related to those changes. The first chapter deals with the molecular evolution of opsins. In addition to the well-known function of opsins as visual receptors, opsins can be related to non-visual photoreception such as photoentrainment of circadian rhythm, photoperiodism, and background adaptation. Molecular phylogenic studies reveal that all opsin genes have evolved from one ancient opsin gene. The evaluation of the functions of each extant opsin protein based on the molecular features enables us to predict the molecular evolution and diversification of opsins during the evolution of animals. These studies shed light on which amino-acid substitutions cause the functional diversification of opsins and how they have influenced the evolution of animals. The second chapter has to do with bitter taste perception, a key detection mechanism against the ingestion of bioactive substances. Genetic and behavioral evidence reveal the existence of "non-taster" Japanese macaques for specific bitter compounds, which originated in a restricted region of Japan. This finding might provide a clue for elucidating the ecological, evolutionary, and neurobiological aspects of bitter taste perception of primates. The third chapter presents an extreme example of the evolution of olfaction, namely, that fully aquatic amniotes have generally reduced their olfactory capacity considerably compared to their terrestrial relatives. Interestingly, the remaining olfactory abilities are quite different among three fully aquatic amniotes investigated: toothed whales have no nervous system structures that mediate olfaction, but baleen whales can smell in air, and it has been suggested that sea snakes smell underwater.

This book introduces to the reader unfamiliar with primatology in Japan three research projects representative of the unique multidisciplinary approach carried out by scientists at Kyoto University, the country’s premier institution for primate studies. The projects are all aimed at understanding the age-old questions, where did we come from, and what makes us unique or similar to our primate ancestors? The first chapter, by Naofumi Nakagawa, focuses on the cultural diversity of social behavior in the Japanese macaque. This chapter reviews research on primate culture, in particular the work on Japanese macaques, then presents what is arguably the first example of a culturally transmitted social convention in the species, called “hug-hug”. The second chapter, by Michael A. Huffman, introduces our current knowledge of self-medication in primates, based largely on a long-term study of wild chimpanzees at Kyoto University’s longest ongoing chimpanzee field in Africa, Mahale, in Tanzania. The suite of behavioral adaptations to parasite infections in chimpanzees is compared with our current knowledge of self-medication in other primates and other animal species. The third chapter, by Yasuhiro Go, Hiroo Imai, and Masaki Tomonaga, describes the ambitious efforts to combine cognitive science and genomics into a new discipline called “comparative cognitive genomics”. This chapter provides an overview of recent advancements in chimpanzee comparative cognition, the construction of a chimpanzee genomic database, and comparative genomic studies at the individual level, looking into factors affecting personality and individuality.