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Published online on October 30, 2006, 10.1073/pnas.0608062103

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Psychology-Biological Sciences
Self-recognition in an Asian elephant

( cognition | mirror self-recognition | theory of mind | intelligence | empathy )

Joshua M. Plotnik *{dagger}, Frans B. M. de Waal *{ddagger}, and Diana Reiss {sect}¶||

*Living Links, Yerkes National Primate Research Center, and Department of Psychology, Emory University, Atlanta, GA 30322; {sect}Osborn Laboratories of Marine Sciences, New York Aquarium, Wildlife Conservation Society, Brooklyn, NY 11224; and Department of Ecology, Evolution, and Environmental Biology, Columbia University, New York, NY 10027

Contributed by Frans B. M. de Waal, September 13, 2006

Considered an indicator of self-awareness, mirror self-recognition (MSR) has long seemed limited to humans and apes. In both phylogeny and human ontogeny, MSR is thought to correlate with higher forms of empathy and altruistic behavior. Apart from humans and apes, dolphins and elephants are also known for such capacities. After the recent discovery of MSR in dolphins (Tursiops truncatus), elephants thus were the next logical candidate species. We exposed three Asian elephants (Elephas maximus) to a large mirror to investigate their responses. Animals that possess MSR typically progress through four stages of behavior when facing a mirror: (i) social responses, (ii) physical inspection (e.g., looking behind the mirror), (iii) repetitive mirror-testing behavior, and (iv) realization of seeing themselves. Visible marks and invisible sham-marks were applied to the elephants' heads to test whether they would pass the litmus "mark test" for MSR in which an individual spontaneously uses a mirror to touch an otherwise imperceptible mark on its own body. Here, we report a successful MSR elephant study and report striking parallels in the progression of responses to mirrors among apes, dolphins, and elephants. These parallels suggest convergent cognitive evolution most likely related to complex sociality and cooperation.

Author contributions: J.M.P., F.B.M.d.W., and D.R. designed research; J.M.P. and D.R. performed research; J.M.P., F.B.M.d.W., and D.R. analyzed data; and J.M.P., F.B.M.d.W., and D.R. wrote the paper.

The authors declare no conflict of interest.

{dagger}To whom correspondence may be addressed at: Department of Psychology, 532 North Kilgo Circle, Emory University, Atlanta, GA 30322.

{ddagger}To whom correspondence may be addressed.

||To whom correspondence may be addressed at: Osborn Laboratories of Marine Sciences, New York Aquarium, Boardwalk and West 8th Street, Brooklyn, NY 11224.

Joshua M. Plotnik, E-mail: jplotni{at}emory.edu
Frans B. M. de Waal, E-mail: dewaal{at}emory.edu
Diana Reiss, E-mail: dlr28{at}columbia.edu

www.pnas.org/cgi/doi/10.1073/pnas.0608062103
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