"For those who study the development of intelligence in the animal kingdom, self-awareness is an important measurement. An animal that is aware of itself has a high level of cognitive ability.
Awareness can be tested by studying whether the animal recognizes itself in a mirror. Many animals fail this exercise miserably, paying scant attention to the reflected image. Only humans, apes and, more recently, dolphins, have been shown to recognize that the image in the mirror is of themselves.
Now another animal has joined the club. In The Proceedings of the National Academy of Sciences, researchers report that an Asian elephant has passed the mirror self-recognition test.
“We thought that elephants were the next important candidate,” said Diana Reiss of the Wildlife Conservation Society, an author of the study with Joshua M. Plotnik and Frans B. M. de Waal of Emory University. With their large, complex brains, empathetic and altruistic behavior and elaborate social organization, Dr. Reiss said, elephants “seemed like cognitive cousins to apes and dolphins.”
The researchers tested Happy, Maxine and Patty, three females at the Bronx Zoo, where the conservation society is based. They put an eight-foot-square mirror on a wall of the animals’ play area (out of view of zoo visitors) and recorded what happened with video cameras, including one embedded in the mirror.
The elephants exhibited behavior typical of other self-aware animals. They checked out the mirror, in some cases using their trunks to explore what was behind it, and used it to examine parts of their bodies.
Of the three, Happy then passed the critical test, in which a visible mark was painted on one side of her face. She could only tell the mark was there by looking in the mirror, and she used the mirror to touch the mark with her trunk.
Dr. Reiss said it was not unusual that only one of the three elephants passed this test; with other self-aware species, large numbers of individuals don’t pass the test either.
But the result with Happy, she said, is a “beautiful case of cognitive convergence” with other self-aware animals. “We knew elephants were intelligent, but now we can talk about their intelligence in a more specific way.”