Aggressive behavior helps male chimpanzees climb the social ladder and maintain influence across their lives. This analysis summarizes a PeerJ study on the topic.
Chimpanzees are widely recognized for their rough social dynamics. They can injury rivals during conflicts, and dominant individuals often curb the actions of those beneath them. Yet, scientists still question why some individuals display aggression while others stay milder in demeanor.
Researchers from Edinburgh University and Duke University studied 28 male chimpanzees living in Gombe National Park, Tanzania. Earlier work by the same team revealed that chimpanzees vary greatly in personality, ranging from social and solitary types to those who are both cooperative and prone to confrontations. The researchers evaluated each chimpanzee’s character through long-term field observations of their interactions and daily behaviors within the troop.
Their findings show that aggressive personalities coupled with a tendency to be less conscientious can lead to greater success, with these individuals often rising higher in the social hierarchy. Although this idea had been proposed before, it puzzled biologists: if aggression is advantageous, why do nonaggressive individuals persist in the population? Prior theories suggested that different behaviors confer benefits at different life stages, such as displaying aggression in youth and calming in adulthood.
The current study challenges that view by indicating that aggressive behavior aided male chimpanzees in dominating and achieving reproductive success throughout life. This raises an evolutionary puzzle about behavioral diversity: some species, like the elephant seal, show high aggression and pronounced dominance strategies to monopolize mating opportunities, with little to no evidence of a cooperative temperament. The study notes that nonaggressive behavior might still offer advantages under certain social or environmental conditions, or could be beneficial for females if these traits cannot be biologically shared between sexes.
Researchers emphasize that more observations are needed to fully understand the balance of traits that shape chimpanzee social structure and reproductive outcomes. (PeerJ study, Edinburgh University and Duke University, cited as the source of these findings.)