The research also shows some of those traits have a neurobiological basis, and that those traits vary according to the biological sex of the individual chimpanzee.
“Our work also demonstrates the promise of using chimpanzee models to investigate the neurobiology of personality processes…The analysis showed that:
- the most fundamental personality trait for chimpanzees is dominance
- that is, whether an animal is a generally dominant and undercontrolled “Alpha,”
- or a more playful and sociable “Beta.”
But those two big categories can be broken down statistically into smaller personality traits in ways that echo the personality structures researchers have repeatedly found in child and adult human subjects.
- Alpha personalities, for example, statistically break down into tendencies toward dominance and disinhibition.
- Beta personalities, on the other hand, show low dominance and positive emotionality.
Further analysis shows these lower order traits also can be statistically broken down into their constituent parts. The research team identified five personality factors that combine differently in each individual chimpanzee:
This echoes a well-known five-factor model of the human personality, although the specific factors are slightly different.
Now, for the neurobiology: many of those chimpanzee traits statistically correlate with the function of a neuropeptide called vasopressin. Chimps who were born with a common variant in the genes that control vasopressin behaved differently than their peers, the males showing more dominance and more disinhibition, but the females less of both.
This research shows:
- not only a neurobiological basis for personality
- but an evolutionary basis as well.
The neurobiological bases of personality can vary according to the biological sex of the subject, at least in chimpanzees. Chimpanzee personality appears to have almost the same ingredients as human personalities, and that similarity seems to arise from the species’ similar neurobiology.
“These results are particularly significant in light of the striking parallels between the major dimensions of personality found between chimpanzees and humans,”