In a new study published in the Journal of Comparative Psychology, researchers from Spain propose that Orcas display personality traits similar to both humans and chimpanzees, including boldness, agreeableness, protectiveness, and playfulness. Because cetaceans and primates diverged from a common ancestor more than 90 million years ago, the new work adds further evidence to the theory that sophisticated emotions and interpersonal behaviors have evolved multiple times in intelligent social animals.

Lead author Yulán Úbeda and her colleagues assessed personality in 24 captive orcas housed at SeaWorld San Diego and the Loro Parque zoo in Tenerife, Spain, using an adapted version of the Five-Factor Model – a popular tool used to characterize a person’s unique personality structure based on the degree to which adjectives corresponding to Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism seem to apply to them. Past animal behavior investigations have used the Five-Factor Model to describe personality in non-human primates, horses, dogs, cats, rabbits, and many others.

"This is the first study to examine the personality traits of killer whales and how they relate to us and other primates," Úbeda, a doctoral student in psychology at the University of Girona, said in a statement. "These similar personality traits may have developed because they were necessary to form complex social interactions in tightly knit groups that we see in killer whales, humans and other primates."

To apply the Five-Factor Model to the cetaceans, Úbeda’s team asked 55 trainers and other park staff who worked closely with the animals to rate each animal in regards to 38 personality description adjectives. After analyzing for significant patterns among these ratings, the scientists revealed four orca personality factors.

The first factor, labeled "Extraversion", was described by the adjectives playful, social, active, cheerful, and gregarious; some of the same adjectives used in the Extraversion factor of the classic Five-Factor Model (FFM) used in humans and chimpanzees. The second factor was labeled as "Conscien-agreeableness" due to raters consistently describing orcas with adjectives – such as patient, predictable, gentle, and generous – that are used in a chimpanzee FFM bracket of the same name. A third factor, defined by the traits associated with the words bold, brave, dominant, protective, intelligent, and laborious, was named "Dominance" (this also corresponds to a chimpanzee label). Finally, based on category-defying adjectives such as helpful, sympathetic, sensitive, organized, and prudent, the authors titled a fourth factor "Careful".  

“Given the small sample size of our study, we must be cautious in our conclusions,” the authors wrote, adding that personality in wild orcas may also differ greatly. “However, the similarity of personality structure across primate species and killer whales suggests evolutionary convergence. Perhaps this type of personality structure, and the distinct individual differences in behavior that this structure implies, are associated with complex sociality (including long-term dyadic relationships) and the cognitive abilities that go along with complex sociality.”

When discussing the link between cetaceans and some primates, Úbeda and her co-authors note that despite the considerable separation on the mammalian tree of life, adaptation to physically dissimilar environments, and wide differences in brain organization, the two clades show similar advanced cognitive abilities (including self-awareness) and relative brain sizes. Furthermore, like chimpanzees, killer whales live in shifting groups, engage in cooperative behavior, and possess cultural traditions and skills that are passed down to future generations.

The team hopes to apply a similar personality assessment to other types of cetaceans in future research.