Three of the "big five" personality traits may be rooted in great apes' personalities earlier than originally thought, according to a study in the March Journal of Personality and Social Psychology (Vol. 90, No. 3).
The study found that extraversion, agreeableness and neuroticism were positively correlated with well-being in orangutans-a finding that dovetails with previous research in chimpanzees and humans. The study suggests that the three personality traits, and their relationship to subjective well-being, were evident in a great-ape ancestor prior to chimpanzees and orangutans' evolutionary split, says researcher James E. King, PhD, a University of Arizona psychology professor.
In the study, King and his colleagues asked 125 employees at 41 different zoos to complete a 48-item personality questionnaire that assessed the degree that such adjectives as "timid" or "anxious" were applicable for each of their facility's orangutans. The survey defined each trait in the context of orangutan behavior. Each of the study's 152 orangutans was rated by at least two employees.
The raters then completed a four-item well-being questionnaire that asked raters to evaluate the orangutan's happiness by asking them to assess such characteristics as the orangutan's frequency of positive and negative moods and how pleasurable and satisfying it appeared to find social interactions with other orangutans. The questionnaire also asked the raters to imagine how happy they would be if they were the orangutan for a week.
King and his colleagues found that even though orangutans are semisolitary apes, those with high extraversion, high agreeableness and low neuroticism tended to be rated as happier. King suggests that the study could bolster the use of human-provided ratings to assess animals' well-being.
"People concerned about the welfare of captive animals should not be concerned about using subjective measures to ensure the animals' positive subjective well-being," King says. "It can be done scientifically-as long as there is strong interrater reliability."