The most compelling evidence for something approaching human-like visual self-recognition is seen only in great apes, despite an impressive range of sometimes highly original procedures employed to study many monkey species

Mirror Self-Recognition. James R. Anderson and David L. Butler. In The Cambridge Handbook of Animal Cognition, Allison B. Kaufman, Josep Call and James C. Kaufman, eds. Jul 2021. https://www.cambridge.org/core/books/abs/cambridge-handbook-of-animal-cognition/mirror-selfrecognition/E00B36F6CE100695BDF781881067D3B0

Summary: This chapter reviews five decades of research on reactions to mirrors and self-recognition in nonhuman primates, starting with Gallup’s (1970) pioneering experimental demonstration of self-recognition in chimpanzees and its apparent absence in monkeys. Taking a decade-by-decade approach, developments in the field are presented separately for great apes on the one hand, and all other primates on the other (prosimians, monkeys, and so-called lesser apes), considering both empirical studies and theoretical issues. The literature clearly shows that among nonhuman primates the most compelling evidence for something approaching human-like visual self-recognition is seen only in great apes, despite an impressive range of sometimes highly original procedures employed to study many monkey species. In the past decade, research has been shifting from simple questions about whether great apes can self-recognize (now considered beyond doubt), to addressing possible biological bases for individual and species differences in the strength of self-recognition, analysis of possible adaptive functions of the capacity for self-visualization, and searching for evidence of self-recognition in a range of nonprimate species.