- WASHINGTON (Reuters) - In
a reflection of their intelligence, bottlenose dolphins named Presley and
Tab at the New York Aquarium have displayed the ability to
recognize themselves
in a mirror -- a quality previously seen only in people and the great apes,
researchers said on Monday.
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- The two male dolphins were housed in a pool
with reflective
glass walls at the aquarium in Brooklyn. Researchers found the dolphins
reacted to their own reflections without the social responses
they displayed
when seeing other dolphins.
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- Testing whether they could distinguish themselves from
other dolphins, the researchers placed markings in non-toxic black ink
on various places on the bodies of 13-year-old Presley and 17-year-old
Tab. The dolphins then swam to the mirror walls and exposed the mark to
the reflective surface in order to look at it.
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- The location where they were marked changed from session
to session -- sometimes, for example, between the pectoral fins, on the
tummy, or on different parts of the head. The dolphins were indifferent
toward the markings on one another.
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- But they swam more quickly to the mirror after a black
mark had been left on their bodies, the researchers found. They spent more
time in front of the mirror after being marked than when they were not
marked, and the first behavior when arriving at the mirror was exposing
the black mark to check it out.
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- "One of the things we try to do is find ways of
characterizing and measuring and comparing intelligence in other animals
across species," Diana Reiss, a scientist in the Wildlife Conservation
Society's Osborn Laboratories of Marine Science located at the aquarium,
said in an interview.
-
- "So this is one of those nice studies that allows
us to say these abilities are not just found in primates, they are also
seen in dolphins. It lets us really get a better understanding of
the nature
of the dolphins' intelligence."
-
- Reiss conducted the study with Lori Marino of
Emory University
in Atlanta. The findings were published in the Proceedings of the National
Academy of Sciences.
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- "There are places in the world where these animals
are being slaughtered," Reiss said. "This perhaps may heighten
our awareness of the importance of conservation efforts and the need to
protect these animals."
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- The great apes -- chimpanzees, gorillas and orangutans
-- all have shown the mirror self-recognition ability in experiments. But
other animals have failed the test in various studies, including lesser
apes, monkeys and elephants.
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- "This is the first conclusive study that shows that
there seems to be a convergence in these abilities between the
large-brained
primates, including humans, and a very different animal (a dolphin) that's
come from a very different background and environmental history, and has
a very different body type and brain organization," Reiss said.
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- In people, the mirror self-recognition ability generally
arises between the ages of 18 months and 2 years and represents
the beginning
of a developmental process of achieving increasingly abstract psychological
levels of self-awareness, including introspection, the
researchers said.
-
- Experts are debating whether this self-recognition in
great apes and dolphins means they are capable of more abstract levels
of self-awareness -- for example, to conceive of their own identity.
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- Marine biologists already knew dolphins were among the
most intelligent animals.
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- "What we see is that they show a lot of the similar
cognitive processes that chimps do -- they have excellent skills
for memory,
they are able to learn and comprehend artificial codes,"
Reiss said.
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- "Their social behavior is quite complex," she
added. "They form long-lasting bonds. There's a great deal of social
learning that occurs between a youngster and its mother."
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- Copyright 2001 Reuters News Service. All rights
reserved.
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