The Times (UK): Dolphins have been declared the world's second most intelligent creatures after humans, with scientists suggesting they are so bright that they should be treated as 'non-human persons.'
Studies into dolphin behavior have highlighted how similar their communications are to those of humans... These have been backed up by anatomical research showing that dolphin brains have many key features associated with high intelligence.
The researchers argue that their work shows it is morally unacceptable to keep such intelligent animals in amusement parks or to kill them for food or by accident when fishing. Some 300,000 whales, dolphins and porpoises die in this way each year...
Dolphins have distinct personalities, a strong sense of self and can think about the future... They are 'cultural' animals, meaning that new types of behaviour can quickly be picked up by one dolphin from another... In one recent case, a dolphin rescued from the wild was taught to tail-walk while recuperating for three weeks.. After she was released, scientists were astonished to see the trick spreading among wild dolphins who had learnt it from the former captive...
One study showed that bottlenose dolphins could recognize themselves in a mirror and use it to inspect various parts of their bodies... In another, captive animals also had the ability to learn a rudimentary symbol-based language.
Dolphins can solve difficult problems, while those living in the wild co-operate in ways that imply complex social structures and a high level of emotional sophistication... Dolphins living off Western Australia learnt to hold sponges over their snouts to protect themselves when searching for spiny fish on the ocean floor... [They] co-operate with military precision to round up shoals of fish to eat... Such observations have prompted questions about the brain structures that must underlie them.
Size is only one factor... When it comes to intelligence, brain size is less important than its size relative to the body... The brain cortex of dolphins [has] the same convoluted folds that are strongly linked with human intelligence. Such folds increase the volume of the cortex and the ability of brain cells to interconnect with each other...
[Zoologist Lori] Marino and [psychologist Diana] Reiss will present their findings at a conference next month... concluding that the new evidence about dolphin intelligence makes it morally repugnant to mistreat them. Thomas White, professor of ethics... who has written a series of academic studies suggesting dolphins should have rights, will speak at the same conference. 'The scientific research... suggests that dolphins are 'non-human persons' who qualify for moral standing as individuals,' he says.