Elephants can recognize themselves in a mirror, joining only humans, apes and dolphins as animals that possess this kind of self-awareness, researchers now report.

"This would seem to be a trait common to and independently evolved by animals with large, complex brains, complex social lives and known capacities for empathy and altruism, even though the animals all have very different kinds of brains," researcher Diana Reiss, a senior cognitive research scientist at the Wildlife Conservation Society in Brooklyn, N.Y., told LiveScience.

The researchers began their experiment by introducing three adult female Asian elephants to a mirror [image] eight feet wide by eight feet high constructed in a private area of their yard at the Bronx Zoo. Making the jumbo-sized mirror as "elephant-resistant" as they could was a challenge, given that "elephants love to constantly push with their heads and manipulate anything they can," explained researcher Joshua Plotnik, a graduate student at Emory University in Atlanta.

"We used a mirror made of plastic -- if we used glass, it would have broken very easily -- and framed it with steel and bolted it to the wall, but we were still worried they'd bring it down," Plotnik told LiveScience. "Luckily that didn't happen. We never saw them attempt to rip the mirror off. They seemed too interested in it to do that."

One of the first things animals capable of recognizing themselves in mirrors do is try exploring the other side of the mirror. Elephants Maxine and Patty did this [video]: they swung their trunks over and behind the wall on which the mirror was mounted, kneeled in front of it to get their trunks under and behind it, and even attempted to physically climb the wall. Remarkably, the elephants did not appear to at first mistake their reflections as strangers and try to greet them, as many animals that can recognize themselves normally do.