Our personalities are at the foundation of who we are. But as unique as we might feel in that mix of positive and negative qualities which makes us individuals, the complex structure of traits that comprise our personalities is not possessed by humans alone.
As it turns out, our closest primate cousins share a nearly identical set of personality traits as we do, and they're structured in the same way, too.
Primatologists have long used a test called the Chimpanzee Personality Questionnaire to assess chimps' temperament, answering questions in different categories about the animals' observed behavior. A research team made up of psychologists, neuroscientists and primatologists closely analyzed the results from 174 chimpanzees and found a familiar pattern.
Chimps could be divided into two basic types: Alpha, who are more dominant and aggressive, or Beta, more social and inclined to play. Within each category, researchers found that sub-traits paired in a statistically similar way they do in people. Much like in humans, five distinct personality factors could be identified in the chimps, traits that blend to form an individual: conscientiousness, agreeability, dominance, intellect and extraversion.