The chimpanzee in the photo was called Frodo and was a stalker, an aggressive and despotic individual who abused the other members of his group, what we could call a real 'bad guy'. He lived in Gombe National Park in Tanzania until he died in 2013 at the age of 37 due to kidney failure. That famous chimpanzee, protagonist of scientific papers and books for his aggressive behavior, both within his community and during attacks on other groups, was for five years the male alfo of his group, a mandate that he exercised brutally until a disease weakened him.
It is one of the animals whose behavior has been documented in more detail, as they observed it throughout their lives. It was Jane Goodall herself who named it after (after the hobbit in The Lord of the Rings), so they could witness how it went from being a mischievous chimpanzee who took the notebooks of the primatologist to throwing stones and beating scientists and tourists who approached. He reached the social pinnacle and had a great offspring: he fathered with six different females eight children, more than any other male in Gombe except another named Wilkie (who had 10).
Frodo is the best example of the conclusions of new research published Monday in the journal PeerJ Life and Environment: Male chimpanzees with more aggressive, greedy and irritable personalities reach the highest rungs on their social ladder and are more successful at siring offspring than other males in their group. Threatening, intimidating, stealing from peers, having tantrums... According to the authors of this study, "science reconfirms that brutal behavior can be an effective path to power." And not only in humans, but also in chimpanzees, as highlighted by this team of scientists from the universities of Edinburgh and Duke, in the United Kingdom.
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- Writing: TERESA GUERRERO Madrid
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But if this is so, the researchers raise the question: why aren't all chimpanzees bullies? Why are there differences in personality? Freud, a brother of Frodo, for example, used other strategies to gain the support of his group, such as grooming (a typical primate social approach behavior called grooming) in what appeared to be efforts to gain their support.
28 chimpanzees observed
The researchers base their study on 37-year observations of the behavior of 28 chimpanzees in Tanzania's Gombe Park. Previous research on these same Gombe chimpanzees, led by Alexander Weiss of the University of Edinburgh and Professor Anne Pusey of Duke University, showed how some chimpanzees are more sociable and others more solitary. Some prefer to be calm while some individuals are authoritarian and tend to provoke fights. Although within the great primates, chimpanzees are the ones that show the most aggressive and territorial behavior (particularly compared to bonobos), there are significant differences between individuals.
The researchers saw that male chimpanzees with certain personality traits — in this case, dominant, unscrupulous individuals — tended to reach more advantageous positions in their lives than other members of their group.
"Personality matters," summarizes one of the leaders of the research, Joseph Feldblum, a researcher in evolutionary anthropology at Duke University, in a press release. For this scientist, the question of why not all males behave this way "is an evolutionary puzzle".
A long-standing theory is that different personality traits pay off at different times in animals' lives. For example, if being aggressive is an advantage for young males, such behavior could backfire when chimpanzees are older. Or maybe certain traits are a disadvantage in youth but an advantage in old age.
But when the team tested this idea, using those 37 years of observational data dating back to some of Jane Goodall's early work at Gombe in the 1970s, they found that the same personality traits were linked to high rank and reproductive success throughout life. That is, what ethologists call "a behavior of high dominance and low consciousness" was associated with a higher social rank, but that type of behavior did not vary throughout his life. And regardless of the social rank that the chimpanzee had at the time of fatherhood, greater dominance and less conscientiousness were related to greater reproductive success and with it, to perpetuate their genes.
The findings suggest that there are other factors that must explain the diversity of personalities in chimpanzees. It could be that what is considered the "best personality" varies according to environmental or social conditions, or that a trait that is beneficial to males turns out to be negative for females, as he suggests Feldblum.Si that were true, then "the genes associated with those behavioral traits would remain in the population," says Alexander Weiss.
The scientists decided to focus on male chimpanzees, who compete vigorously for a position in a dominance hierarchy that influences reproductive success, and not females because, as they explain, "although the range of female dominance is also associated with reproductive success, in the Gombe community it seemed to depend little on the competitive interactions they made on a daily basis. The range of male dominance changes more dynamically and seems more likely to be influenced by variation in personality traits."
The personality of animals, a taboo
As the authors recall, we must not forget that until not many years ago, the mere suggestion that animals have a personality was considered a taboo. Jane Goodall was accused of anthropomorphism when she described some of Gombe's chimpanzees as "bolder" or "more fearful" than others, or defined them as "affectionate" and "cold."
But the research carried out in the following decades has proved the British primatologist right. Since then, ethologists who study the behaviors of all kinds of animals have found different personalities among members of the same species. Weiss says animal personality ratings have been shown to be as consistent from observer to observer as similar measures of human personality.
- Articles Teresa Guerrero
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