The project, which studied 134 bottlenose dolphins from around the world, has helped researchers understand how certain human personality traits have developed independently of immediate environments.
Lead author Dr Blake Morton said it is the first time dolphins’ personalities have been studied in this way.
Dr Morton, a psychology lecturer at the University of Hull, told the PA news agency that the team chose dolphins because, like primates, they are intelligent animals who live in social groups but are very different in many other ways.
He said the research has identified a convergence of certain personality traits – especially relating to curiosity and sociability – despite dolphins evolving in a completely different environment from primates and their last common ancestor living around 95 million years ago.
Dr Morton said: “Dolphins, like many primates, have brains that are considerably larger than what their bodies require for basic bodily functions; this excess of brain matter essentially powers their ability to be intelligent, and intelligent species are often very curious.”
He said: “Dolphins were a great animal for this kind of study because, like primates, dolphins are intelligent and social. We reasoned that if factors such as intelligence and gregariousness contribute to personality, then dolphins should have similar personality traits to primates.”
Dr Morton explained that the most widely accepted model of human personality is defined by five traits – summarised as openness, conscientiousness, extraversion, agreeableness and neuroticism. These are replicated everywhere in humans, regardless of environment.
He said that extensive studies have looked at the extent to which these traits are shared by primates but his team wanted to look at intelligent animals in a completely different setting.
“Scientists still do not fully understand why our behaviour comes down to those five traits, so one way of doing that is to compare ourselves to other animals – what we share in common and why,” Dr Morton said.
He said: “Most research has been done on primates so we decided to do something different and look at dolphins.
“No one’s ever studied personality in dolphins before in the way we have.”
He said: “We’ve known for some time that dolphins are similar to us in other respects – for instance, you can just watch dolphins on television and see they’re very obviously smart and social.
“We see those characteristics mirrored in our own behaviour.
“But even on top of that, their personalities are also similar to our own in some respects.”
Dr Morton said: “I don’t want people to misinterpret that and say human and dolphins have the same personality traits – they don’t. It’s just that some of them are similar.”
He said: “It is vital researchers conduct further studies because not only will it lead to a better appreciation for species living within the depths of our oceans, it will lead to a better understanding of ourselves.”
The authors collected data on 56 male and 78 female dolphins, from different facilities across eight countries, including Mexico, France, the United States, Curacao, the Netherlands, Sweden, the Bahamas, and the Cayman Islands.
They assessed each dolphin’s personality using questionnaires given to staff from each facility who knew them well.
The study, Personality Structure In Bottlenose Dolphins, began in 2012 and is published in the Journal of Comparative Psychology.
The team also included Dr Lauren Robinson from the University of Veterinary Medicine Vienna and Georgia State University, Ms Sabrina Brando from AnimalConcepts, and Dr Alexander Weiss from the University of Edinburgh.