Psychologists can get a pretty clear picture of someone's personality by evaluating to what degree they express traits known as the "Big Five" — openness, conscientiousness, extroversion, agreeableness and neuroticism. These factors are thought to be rooted in biology and to transcend cultural differences, but a new study of an indigenous Bolivian society shows the traits might not be universal after all.

Researchers spent two years studying more than 1,000 Tsimane forager-farmers, who live in isolated communities, each ranging from 30 to 500 people. Most are not formally educated, and they live in extended family clusters, sharing food and labor and limiting contact with outsiders.

The team first surveyed adults in the villages with a standard questionnaire (translated into the Tsimane language) that assesses the Big Five personality traits. Next the researchers asked Tsimane participants to evaluate their spouse's personality. This second part revealed that the subject's personality as reported by his or her spouse also did not fit with the Big Five traits. The researchers found that their results held true even when they controlled for education level, Spanish fluency, gender and age.

The team instead discovered evidence of a pair of broad traits that could be considered the Tsimane "Big Two." The researchers labeled one prosociality — socially beneficial behavior, which among the Tsimane, looks like a mix of items under the extroversion and agreeableness portions of the Big Five. The other trait is industriousness, which blends the efficiency, perseverance and thoroughness found in the conscientiousness portion of the Big Five, the researchers said.

The team says their results don't support the universality of the Big Five, and they speculated that the social structure of the Tsimane could have resulted in a trait structure different from the Big Five.

"Individuals in all human societies face similar goals of learning important productive skills, avoiding environmental dangers, cooperating and competing effectively in social encounters, and finding suitable mates. In small-scale societies, individuals have fewer choices for social or sexual partners and limited domains of opportunities for cultural success and proficiency. This may require abilities that link aspects of different traits, resulting in a trait structure other than the Big Five," the team wrote.

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The research was detailed online in December in the Journal of Personality and Social Psychology.

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