The orca (Orcinus orca), also known as the killer whale, has the second largest brain of all marine mammals. They have their own local dialects, coordinate each other in sophisticated hunting teams, teach one another specialized methods of hunting, and pass on behaviors that can persist for generations. These are really smart creatures, who are also extremely socially savvy. What’s more, according to a new study, orcas display distinct personality traits such as playfulness, cheerfulness, and affection, akin to chimps or even humans.

Researchers assessed the personalities of 24 captive orcas at  SeaWorld Orlando, SeaWorld San Diego and the Loro Parque zoo in Tenerife, Spain. The animals’ trainers and other staff that worked closely with the killer whales had to complete surveys that ranked each animal on a list of 38 personality traits. The traits were analyzed and then compared with previous studies of the same personality traits for chimpanzees and humans.

“This is the first study to examine the personality traits of killer whales and how they relate to us and other primates,” lead researcher Yulán Úbeda, a doctoral student in psychology at the University of Girona in Spain, 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.”

The psychologists measured personality traits with the ‘Big Five’ model, which describes personality across five dimensions: openness, conscientiousness, extraversion, agreeableness, and neuroticism. This simplified model describes personality traits using a combination of single adjectives and descriptive phrases.

The results suggest that killer whales have personality traits that are similar to both humans and chimpanzees, although they lean more towards chimps. Particularly, killer whales scored on par with chimps and humans for extraversion (e.g, playful, gregarious, sociable). Killer whales and chimps also shared personality traits for conscientiousness (e.g., constant, stubborn, and protective) and agreeableness (e.g., patient, peaceable and not bullying).

Killer whales live in tightly knit social groups known as pods. Individuals hunt together, share food, and communicate using sophisticated language.  Remarkably, orcas — which are actually a species of dolphins found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas — can also imitate sounds from bottlenose dolphins, sea lions, and even humans. The fact that orcas have personality is perhaps best illustrated by the heartbreaking case of a 20-year-old killer whale, known as J-35 or Tahlequah, who began pushing her dead newborn calf off the coast of Vancouver Island. The grieving mother kept the calf afloat for 17 days while swimming hundreds of miles. Other members of the pods helped the mother, even though this had hurt the pod’s ability to hunt. The behavior was recorded in July and gained international news coverage.

“It is unbelievably sad,” Brad Hanson, a wildlife biologist at the Northwest Fisheries Science Center, told The Seattle Times. “It reflects the very strong bonds these animals have, and as a parent, you can only imagine what kinds of emotional stress these animals must be under, having these events happen.”

Scientists are not sure if killer whales really do feel grief — a complex emotion that’s difficult to gauge, although it may be present in species that live in tight-knit groups, such as chimpanzees, elephants, and giraffes.

“Some previous studies suggest that the mother’s contact with the lifeless body could be important for the mother to make a psychological adjustment to the death of her offspring,” Úbeda said. “In any case, those behaviors show how complex these animals are.”

The current study suggests that the personality traits of killer whales and primates evolved independently of one another, as a byproduct of the advanced cognitive abilities required for complex social interaction — essentially convergent evolution in action.

As a caveat, the study, which was published in the Journal of Comparative Psychology, was performed solely on captive orcas, which have altered personalities like increased neuroticism and aggression. To the authors’ merit, it’s incredibly challenging to assess the personality traits of killer whales in the wild. That being said, the findings do not necessarily reflect the personality traits of killer whales found in the wild.