Pleasure in mammals is associated with a release of the neurotransmitter dopamine. The behavior of dolphins and whales in captivity indicate that these animals experience pleasure. Dr. Sam Ridgway, president of the National Marine Mammal Foundation and renowned whale and dolphin expert for 50 years, and colleagues are the first to offer physical evidence that dolphin and beluga whales experience pleasure. The research was published in the Journal of Experimental Biology on Aug. 13, 2014.
Dolphins and whales are trained to perform activities with a food reward in captivity. In time the food reward is replaced with a sound signal that indicates the animals will receive a food reward at a time in the future. In both situations, dolphins and beluga whales respond with a characteristic vocalization or squeal.
Sam Ridgway’s wife Jeanette noticed that the squeals made by dolphins and whales when they received a food reward were very similar in pattern and context to the squeals of delight that human children make in similar situations. Ridgway searched the archives of whale and dolphin vocalizations that he and his colleagues have recorded for almost 50 years to discover evidence that whales and dolphins experience and express pleasure. Ridgway has produced the first physical evidence that these animals experience pleasure and make that pleasure known by vocalizations.
Dopamine release takes about 100 milliseconds regardless of species. If an animal makes a vocalization in response to a food reward after the release of dopamine then the vocalization would be considered to be an expression of pleasure. The researchers found that the squeal of delight upon receiving a food reward took an average of 151 milliseconds in dolphins and 250 milliseconds in beluga whales. The delayed response time indicates these animals experience pleasure and express it in vocalizations.
The brain structure and brain chemistry of humans, whales, and dolphins are not extremely different. While whales and dolphins may not be as “smart” as people the research indicates that they experience pleasure and express that pleasure on a routine basis. The study makes one wonder just what their cat or dog may be expressing with the variety of antics that these animals engage in.