Chimpanzees and bonobos are often viewed as representing two opposite sides of human nature – the conflict-prone chimpanzee versus the peaceful bonobo. However, a new study published in the journal Current Biology challenges this perception by revealing that within their own communities, male bonobos are actually more aggressive than male chimpanzees. More aggressive males in both species were found to have more mating opportunities, shedding light on the complex nature of aggression within these primates.
The study, led by anthropologist Maud Mouginot from Boston University, is the first to directly compare the behavior of bonobos and chimpanzees using the same field methods. By analyzing rates of male aggression in three bonobo communities in the Democratic Republic of Congo and two chimpanzee communities in Tanzania, the researchers sought to gain insight into how aggression is utilized within each species for reproduction purposes. While previous research has explored aggression in these primates, this study takes a unique approach by focusing specifically on male aggression.
Through detailed observations conducted via “focal follows,” where individual behaviors were tracked throughout the day, the researchers found that male bonobos exhibited higher rates of aggression compared to chimpanzees. Bonobos engaged in nearly three times more aggressive interactions and physical aggressions than chimpanzees. Interestingly, male bonobos directed their aggression mainly towards other males, while chimpanzees were more likely to act aggressively towards females. Chimpanzee aggression also often involved male coalitions, which could potentially explain why aggression is less frequent in chimpanzee communities.
Despite the prevailing belief that bonobos exhibit more peaceful behavior compared to chimpanzees, the study’s findings challenge this notion by demonstrating that more aggressive male bonobos actually had greater mating success. This contrasts with chimpanzees, where male-dominated hierarchies often lead to coercion of females into mating by male coalitions. The results suggest that female choice in mate selection may not always favor the “nicer” males, as aggressive males in both species were observed to have higher mating success.
Although the researchers were unable to assess the severity of aggressive interactions in terms of resulting injuries, future studies aim to collect this data and explore variations in aggressive behavior among different communities and subspecies of bonobos and chimpanzees. Mouginot emphasizes the importance of complementing the study with data from other field sites to obtain a more comprehensive understanding of aggression within and between species. Ultimately, the study highlights the complexity of aggression in these primates and challenges previous assumptions about the peaceful nature of bonobos compared to chimpanzees.
