Marine biologists and philosophers have joined forces to support a controversial declaration of rights for whales and dolphins on the grounds that their astonishing intelligence and emotional empathy puts them on a par with humans.

Research into the complex behaviour of cetaceans – whales, dolphins and porpoises – is revealing that these sea mammals are so highly evolved and complex in terms of their behaviour that they deserve special protection with a universal bill of rights, they said.

Dolphins and whales have complex vocal communications and are able to learn an astonishing variety of behaviours when they come into contact with humans, such as cooperative fishing with native fishermen. The proponents of the bill of rights argue the cetacean mind is so advanced and self-aware that whales and dolphins should be classified as "non-human persons" who deserve the right to life, liberty and wellbeing. "A person needs to be an individual," said Tom White, a philosopher at the Hilton Centre for Business in Los Angeles. "If individuals count then the deliberate killing of individuals of this sort is ethically the equivalent of deliberately killing a human being.

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"The captivity of beings of this sort particularly in conditions that would not allow for a decent life is ethically unacceptable, commercial whaling is ethically unacceptable. You can't say its all about the size of the population. We're saying the science has shown that individuality, consciousness, self-awareness is no longer a unique human property. That poses all kinds of challenges."

The declaration of rights for cetaceans states that every individual dolphin, whale and porpoise has the right to life and liberty and that not only should they not be killed by hunting, but none should be kept in captivity or servitude or subject to cruel treatment. It states that no cetacean can be the property of any individual or government and calls for the legal protection of their natural environment and a ban on any activity that disrupts their "cultures", which could include underwater military sonar that disturbs their acoustic communications.

"The similarities between cetaceans and humans are such that, like us, they have an individual sense of self. We can look internally and say that we have emotions, personality and sense of self. They do as well," said Dr White. "What we see in cetaceans is that humans need individual freedom more than whales and dolphins. But dolphins need social life more. When I look at captive animals I don't say, 'gee, they've got no freedom', I say, 'they have no social life'."

Lori Marino, of Emory University in Atlanta, said people can support the call for a bill of cetacean rights by not going to sea life parks that keep dolphins, porpoises or whales. "Once you shift from seeing a being as a property ... to a person, an autonomous entity that has a right to life on his or her own terms, the whole framework shifts," she said.

Marine intelligence: brains of the oceans

* In self-awareness experiments, dolphins identify their reflections in a mirror.

* Wild orcas in Patagonia supported a member of the social group with a damaged jaw by feeding it for more than a year.

* Tests on captive dolphins show they have the ability to indicate "I don't know" when pressed to make a choice between two alternatives.

* A captive dolphin was found to have exploited a reward for picking up rubbish in its tank by hiding a sheet of paper and plucking off small segments when keepers with fish rewards were nearby.