Overview of Brain Evolution: Lobe-Finned Fish vs. Ray-Finned Fish

Abstract

Recent advances in infrared eye-tracking technology have allowed researchers to examine social attention in great apes in great detail. In this chapter we summarize our recent findings in this area. Great apes, like humans, exhibit spontaneous interest in naturalistic pictures and movies and selectively attend to socially significant elements such as faces, eyes, mouth, and the targets of others' actions. Additionally, they follow the gaze direction of others and make anticipatory looks to the targets of others' actions; the expression of these behaviors is adjusted flexibly according to the social contexts, and the viewers' memories and under-standings of others' goals and intentions. Our studies have also revealed systematic species differences in attention to eyes and gaze following, particularly between bonobos and chimpanzees; several lines of evidence suggest that neural and physiological mechanisms underlying gaze perception, which are related to the individual differences within the human species, are also related to the species differences between bonobos and chimpanzees. Overall, our studies suggest that cognitive, emotional and physiological underpinnings of social attention are well conserved among great apes and humans.