Do nonhuman primates (such as chimpanzees and orangutans) have personalities? And how similar are these personality to humans who share an evolutionary history with them?
Research looking at personality in humans has identified what is known as the Five-Factor Model of Personality with five broad personality factors describing personality. These factors (also known as the Big Five personality traits) are: openness to experience, conscientiousness, extraversion, , agreeableness, and neuroticism which appear to underlie the rich variety of ways that humans differ from one another. The Five Factor Model has inspired countless research studies as well as psychometric personality measures commonly used in psychology today. It also highlights the role of biological factors in shaping how personality grows and develops as we become more mature.
While research into the Five-Factor Model has shown that personality traits change over time, identifying personality changes in nonhuman primates has always been difficult. Since nonhumans are not capable of speech, measuring personality usually involves careful observation of how they interact with other nonprimates using a rating system. Based on behaviour ratings, different personality traits that appear equivalent to the Big Five Factors seen in humans have been identified in nonhuman primates as well. While some researchers remain skeptical about using behaviour ratings to measure personality in nonhumans, numerous research studies have shown intriguing similarities between humans and nonhumans in how personality changes develop across the lifespan.
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