Chimpanzees have a curious way of grooming themselves: they simultaneously extend one arm above their head and hold their partner’s hand while licking themselves with the other arm.
In this regard, new research from the universities of Utrecht (Netherlands) and London (United Kingdom) analyzed these behavior patterns over more than 10 years of observation of these animals, and revealed that this iconic gesture can be transmitted through social networks. . learning biases, something thought to be characteristic of the human species.
“Dominant and older individuals influence the styles in which the chimpanzees adapt to a sociocultural costume, in this case, the need to tighten their hands to acclimate themselves”, tells SINC Dutch researcher Edwin van Leeuwen, one of the firmants of this job. Furthermore, as young people grow up, they adapt their styles to the specific way of shaking hands in the group, which indicates compliance processes.”
At the same time, “there’s a pattern in the style of some bands, and in some ways ‘imitation’ implies some kind of driving force, but we don’t know why,” he says.
The work is based on more than a decade of observations of two groups of 71 chimpanzees in semi-freedom at the Chimfunshi Wildlife Orphanage Trust in Zambia.
The study is based on observation from 2007 to 2019 of the behavior of two groups of 71 chimpanzees in semi-freedom in the Chimfunshi Wildlife Orphanage Fundt, an organization dedicated to the protection and welfare of these and other animals in Zambia (Africa).
In this way, the scientific team, coordinated by van Leeuwen and William Hoppitt, discovered that the different ways of holding hands during grooming exhibited by young chimpanzees were notably influenced by both majority bias and supremacy bias, often implying in unmatched pairs. matched and older.
Social learning strategies
“The social learning strategies provide important information about the implicit capacities of chimpanzees to develop what is supposedly a cultural characteristic of humans: cumulative cultural evolution”, point out the researchers.
“Older, dominant individuals influence the styles by which chimpanzees adapt a sociocultural habit, in this case, shaking hands to groom themselves”
Edwin van Leeuwen, one of the research coordinators
In this context, the researchers took into account that in humans there are multiple driving forces behind the formation and maintenance of group differences in cultural behavior.
So they studied the state of the art and wondered if perhaps similar ‘driving forces’ could influence the way some chimpanzees shake hands in the same way.
Along the same lines, the research points out that “mothers shape the behavior of young people, with whom some grow up assimilating that handshaking is part of chimpanzee life”. However, the authors argue that the specific style in which they do it seems to respond to a form of social learning.
Each one with their own style
And that’s it, each group has its own style of shaking hands during grooming, as explained by the researcher. “Those who have already incorporated this gesture have their own way of doing it, something that is learned as they grow up, however, many groups of chimpanzees never adopted this custom”, she clarifies.
But while it may seem that some chimpanzees exert influence over others, that doesn’t mean that those who don’t adopt this habit will be rejected or punished. “So far, we have no record of animals rejecting others for not adhering to social norms,” the Dutch expert told SINC.
While it may seem that some chimpanzees influence the rest, that doesn’t mean that those who don’t adopt this habit will be rejected or punished.
According to previous research, many animals use social learning strategies to transmit cultural traditions, through which individuals adopt patterns of behavior after observing and interacting with those around them.
However, these studies have mostly focused on different behaviors related to foraging, mating, and rearing or tool use, despite evidence that some animals have social customs like humans.
Human social interactions, like other traditions, are shaped by our cultures and through them behaviors, attitudes and beliefs can be transmitted and developed.
In this sense, human beings have two main predispositions to acquire social customs: on the one hand, the majority bias, where individuals conform to those around them, and, on the other hand, the dominance or supremacy bias, where they imitate the others. prestige or experience.
Routes of cultural transmission in the social life of animals
However, although chimpanzee behavior is explained by these biases in other contexts, so far it is unclear how the social custom of shaking hands during grooming is transmitted.
Here we show that this selective imitation is also present in the cultural life of other animals, in this case chimpanzees.
Edwin van Leeuwen
Furthermore, this does not necessarily mean that human cultural practices are shaped in the same way. “Some scholars argue that culture has played a decisive role in our biological success and that culture derives its adaptation through selective imitation of others or through individual learning” in the words of van Leeuwen.
“Here we show that this selective imitation is also present in the cultural life of other animals, in this case chimpanzees. Furthermore, if we want to know more about social learning in the contexts of material animal culture – for example, cracking nuts – this work could pave the way for further investigations that explicitly identify forms of cultural transmission in the social life of animals”, he concludes.
Reference:
Edwin JC van Leeuwen, Edwin JC van Leeuwen. “Culturally biased transmission of a social custom in chimpanzees”. Science (2023)
