Here's looking at me

Mirrors have revealed an interesting and exclusive property within the animal kingdom: only humans and their closest great-ape relatives appear able to recognize themselves when confronted with a mirror. Even in humans, it is an ability that does not appear reliably until around two years of age. But new research suggests that a very distant species from our own great-ape family may have developed this ability.Diana Reiss at Columbia University and Lori Marino at Emory University now believe they have evidence that the bottlenose dolphin may be capable of self-recognition in a mirror. In the May 8 issue of Proceedings of the National Academy of Sciences USA (2001, 98:5937-5942), the two researchers describe an extensive series of tests with two captive-born dolphins which revealed that the animals used mirrors to view themselves after being marked at various sites on their bodies.The researchers devised a series of trials to provide sufficient numbers of control and test situations to examine the dolphins’ reactions effectively. They also tested them under two conditions. As they were used to being in pools with some reflective surfaces they tested responses in such a pool and also in a pool with non-reflective surfaces which contained a mirror during certain sessions.The animals were either given a 6cm mark with temporary, non-toxic ink, sham-marked with the same tool containing no ink, or not marked. The researchers took video film of the dolphins’ subsequent behaviour.From the analysis of the videos, marked animals spent significantly greater time in self-directed behaviour at the mirror surface where they oriented themselves so that the mark could be visible to them, than when they were sham-marked or not marked at all.The researchers conclude that bottlenose dolphins, in spite of their markedly different brain structure and great evolutionary distance from the great apes, have the ability for self-recognitionself-recognition too.Fig. 1Eyes to themselves: new evidence suggests the bottlenose dolphin may be capable of self-recognition in mirrors. (Science Photo Library).View Large Image | View Hi-Res Image | Download PowerPoint Slide