US: Humans, chimps and dolphins are not the only species struck by their own image staring back at them. Research in America demonstrates that the list of self-observers has become longer, writes Thomas Maugh
Cats might try to pick a fight with their image in a mirror. Dogs might bring a gift of food to what they think is a new-found friend. But humans and chimpanzees - and maybe dolphins - have been thought to be the only species that primp and groom before the mirror because they recognise themselves.
Now elephants can be added to the list, researchers from the US Yerkes Primate Center and the Wildlife Conservation Society (WCS) have reported in the online version of the Proceedings of the National Academy of Sciences.
Three female elephants at the Bronx Zoo in New York examined the insides of their mouths, studied their ears and showed other signs of self-awareness, said Yerkes graduate student Joshua Plotnik, a co-author along with Frans de Waal of Yerkes and Diana Reiss of the WCS.
Most importantly, an elephant named Happy used her trunk to touch a mark on her head that she could see only in the mirror - a standard test of self- awareness developed 35 years ago by biologist Gordon Gallup of the State University of New York at Albany.
The experiment provided what was deemed "compelling" evidence that the animals have a strong sense of self, said Gallup, who was not involved in the research.
That self-recognition might underlie the social complexity elephants exhibit. It also might be associated with other traits common among large-brained animals: empathy and selflessness.
Previous experiments had failed to produce such recognition, but they used small mirrors out of the animals' reach. The new study used a 2.5m by 2.5m (8ft by 8ft) "elephant-proof" mirror made of plastic framed in steel.
The animals initially tried to look behind the mirror, swinging their trunks over the mirror and wall, kneeling in front to look under it and even attempting to climb the wall holding the mirror. Such behaviour is typical for self-aware animals, said de Waal.
That was followed by an eerie sequence in which the animals made slow, rhythmic movements while tracking their reflections. Then, like teenagers, they got hooked.
As a result of this study, de Waal said: "The elephant now joins the cognitive elite."
All three animals conducted oral self-examinations. Maxine, a 35-year-old female, even used the tip of her trunk to get a better look inside her mouth. She also used her trunk to slowly pull her ear in front of the mirror so she could examine it - these were "self-directed" behaviours the zookeepers had never seen before.
Moreover, Happy (34) passed the most difficult measure of self-recognition: the mark test. The researchers painted a white X on her left cheek, visible only in the mirror.
Later, after moving in and out of view of the mirror, Happy stood directly before the reflective surface and touched the tip of her trunk to the mark repeatedly - an act that, among other insights, requires an understanding that the mark is not on the mirror but on her body.
The researchers also placed a transparent "sham" mark that could not be seen in the mirror on Happy's right cheek, to see if the feel of that mark on the skin alone might cause her to touch that spot. It did not.
Marc Hauser, a Harvard biologist who has studied self-recognition in cotton-top tamarins, said that the mirror test is valuable but that other tests can also shed light on "what kinds of thoughts animals have about themselves and others".
Monkeys do well on other tests of self-awareness, for example, including some that measure their awareness of gaps in their knowledge. "They're good at knowing what they don't know," Hauser said.
Some birds are especially good at knowing what other animals know about them: jays will move hidden food if they realise another bird has been watching them hide it. - (LA Times-Washington Post service)