Dolphins May Seek Selves in Mirror Images
Bower, B., Science News
In Greek mythology, the lad Narcissus wasted away because he couldn't bear to stop staring at his reflection in a pool of water. Although people have a stranglehold on such narcissistic pursuits, dolphins recognize their own reflections much as folks do, according to a new study.
The findings, published in the May 8 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, support a theory that the neural capacity for at least a basic type of self-awareness evolved separately in dolphins and humans.
"We've documented a level of self-awareness in bottlenose dolphins that occurs rarely in the animal world," says psychobiologist Diana Reiss of Columbia University. Reiss conducted the new experiments with psychologist Lori Marino of Emory University in Atlanta.
Before these trials, two captive-raised dolphins had ignored sham ink applications that left no visible marks. After the investigators marked with temporary ink on various parts of the dolphin's bodies, the animals began perusing the marks by positioning themselves in front of mirrors in their enclosure.
After the dolphins repeatedly viewed reflections of the real ink marks, the researchers repeated the sham marking. This time, the dolphins tried to find mirror images of the sham marks, confirming the presence of a self-aware curiosity, Reiss and Marino argue.
The researchers videotaped the adult dolphins during a series of 30-minute sessions after application of either a visible mark or a later sham. Mark locations varied from one trial to the next. Examples include just above the right eye, behind the top fin, and below the left, bottom fin.
Each dolphin repeatedly maneuvered his body in front of the mirrors to scrutinize visible marks and hunt for ensuing sham marks, the researchers say. This self-directed behavior, including neck stretching and body turning, lasted for periods ranging from 10 seconds to the entire videotaped period.
While searching for marks, the dolphins didn't display any social behaviors, such as threatening squawks, that might be expected if they regarded the reflection as another dolphin. …