This is the VOA Special English SCIENCE REPORT.
Many people believe that dolphins are among the smartest animals on Earth. Dolphins are warm-blooded sea animals. Recently, scientists discovered that dolphins could do something that humans can do. They say dolphins can recognize themselves in a mirror, a shiny piece of glass.
Scientists Diana Reiss and Lori Marino discovered this special skill. They did separate studies with two bottlenose dolphins at the New York Aquarium in Brooklyn, New York. Their findings were published in a National Academy of Sciences publication.
The researchers say their study proves that dolphins have a high level of intelligence. Mizz Reiss and Mizz Marino say that dolphins have a level of self-knowledge because they are able to recognize themselves in mirrors. This level of self-knowledge has been identified only in humans and one other kind of animal - the great apes.
The two researchers discovered this by using a test created thirty years ago by scientist Gordon Gallop. Mr. Gallop placed a mark on animals. He wanted to find out if the animals were able to recognize themselves in a mirror. He found that when animals study the marking in a mirror, they show signs of self-recognition.
Mizz Reiss and Mizz Marino tested the two dolphins many times with two markers. They used one marker filled with ink that made real marks. They also used a marker filled with water that did not make a mark. Each dolphin repeatedly swam to the mirror to inspect the place where it had been marked with ink. The scientists say the dolphins turned and positioned themselves to get a better look in the mirror.
Mizz Reiss says that most animals either refuse to look at a mirror. Or they react aggressively as if the image were another animal.
Experts say this new research provides more information about how the brain develops. During the past sixty-million years, the brains of dolphins and primates have developed differently. Primates include humans, apes and monkeys. For example, dolphin brains lack a front part, or lobe, found in primate brains. Also, one area of dolphin brains is organized differently from that of primates. Mizz Reiss says that even though these animals have developed differently over time, their brains have developed a similar intelligence.
This VOA Special English Science Report was written by Jill Moss.