Swimming with dolphins is an effective treatment for mild to moderate depression, the results of a new study indicate. According to the researchers, these findings support the theory of biophilia, which is concerned with how human health and wellbeing are dependent on our relationships with the natural environment.The study involved 30 patients diagnosed with mild or moderate depression. Half were assigned to an experimental group, while the other half acted as a control group.

Over a two-week period, those in the experimental group swam and snorkelled with dolphins for one hour a day. Those in the control group also swam and snorkelled for one hour a day, however without the presence of dolphins. Depression scores were measured before the study and at the end of the two week period. The researchers found that the average severity of depressive symptoms was more reduced in the experimental group. In fact, the effects exerted by the animals were 'significantly greater than those of just the natural setting'. "The echolocation system, the aesthetic value and the emotions raised by the interaction with dolphins may explain the mammals healing properties", they said.

The researchers also found that three months after the study, the participants reported lasting improvement and did not require treatment. "This suggests that in patients with mild or moderate depression, using drugs or conventional psychotherapy may not be necessary when biophilic treatment with animals is used", they concluded.

Details of this study are published in the British Medical Journal.