When we were kids, we had more friends than we do at the present. There are only few true friends left when we grow up. These kinds of friendship focus on maintaining positive and meaningful relationships. Based on it, we have future-oriented cognition.
But with chimpanzees, their friendships may not actually be tied to thinking about the future, a recent study published in Science on the wild chimpanzees living in Uganda’s Kibale National Park suggests. Because we are so closely related to chimpanzees, these findings in the wild chimps might also apply to people.
In this study, a team of researchers analyzed 78,000 hours of observations of 21 male chimpanzees made between 1995 and 2016 at the Kibale National Park. According to Rosati, a unique feature of this study is the value that exists in the long-term collection of data. “We used 20 years of data for this paper. [It] lets us look at this really detailed information about what’s going on in these chimpanzees’ social lives,” Alexandra Rosati, an evolutionary psychologist at the University of Michigan and one of the study’s lead investigators, says. The findings surprised her.
Like humans, as these chimpanzees grew older, they increased the number of mutual friendships and decreased the number of one-sided friendships they maintained. In these mutual friendships, aged chimpanzees were more likely to groom each other, and they engaged in grooming for longer periods of time. This suggests these friendships were of high value to the chimpanzee.
It almost goes without saying that trust is a defining element of genuine human friendship. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, suggest that the same holds true among chimpanzee pals. Their findings suggest that friendship based on trust has evolved much earlier than previously thought and is not unique to humans.
“Humans largely trust only their friends with crucial resources or important secrets,” said Jan Engelmann of the Max Planck Institute for Evolutionary Anthropology. “In our study, we investigated whether chimpanzees show a comparable pattern and extend trust selectively toward those individuals they are closely bonded with. Our findings suggest that they do indeed, and thus that current characteristics of human friendships have a long evolutionary history and extend to primate social bonds.”
The findings suggest that human friendship is not so unique. “Human friendships do not represent an anomaly in the animal kingdom,” Engelmann said. “Other animals, such as chimpanzees, form close and long-term emotional bonds with select individuals. These animal friendships show important parallels with close relationships in humans. One shared characteristic is the tendency to selectively trust friends in costly situations.”