Many animal communities have traditional ways of doing things. Some of these cultural traditions have bearing on the survival of their adherents. For example, some Capuchin Monkey and Chimpanzee populations are better at cracking open nuts with stone tools than others. Similarly, some Chimpanzee populations are better than others at scooping out ants/termites from holes in trees or the ground using sticks.
However, some cultural traditions provide no material benefits. Yet, they remain distinct because all individuals in a group conform to their group’s traditions to fit in. Sometimes, tendency to conform is so strong that when individuals migrate from one community to another, they abandon the traditions of their previous group readily and adopt traditions from the new group.
Chimpanzees in West Africa are known to abandon their previous tool preference and adopt the tool preference of their new community after migrating. They do so regardless of their proficiency in using tools of the old or new group. Rule #1 in chimp communities seem to be - fall in line or get kicked out.
According to a recently published paper, chimpanzee communities in Zambia have unique group-preferences when it comes to handclasps. In some communities during grooming, both chimpanzees “raise an arm overhead and then either one clasps the other’s wrist or hand, or both clasp each other’s hand”. They then groom each other with the other arm. Researcher Edwin van Leeuwen found that this behavior (known as handclasp) is surprisingly similar within groups, but strikingly dissimilar between groups.
There are various styles of handclasps, including palm-to-palm, wrist-to-wrist, and forearm-to-forearm. Van Leeuwen observed two groups of chimpanzees over a period of 12 years (N=71) to study which handclasp styles were preferred by individuals.
One group preferred palm-to-palm handclasps, with the preference remaining unchanged for the whole duration of the study. Individuals in this group were 2.93X more likely to engage in a palm-to-palm handclasps compared to the other.
Even though group compositions kept changing with time, due to immigrations and emigrations, group preferences remained the same. Chimpanzees who emigrated into a group adopted the group’s preferred handclasp.
The tendency to conform has created stable social cultures, the kind we normally see in human communities.
According to van Leeuwen, “these findings indicate that human culture, including its arbitrary social conventions and long-term stability, is rooted in our evolutionary history”.
Read more about the study here.
