Psychology encompasses not only the study of human behavior, but also of other species. Research often focuses on studying psychological characteristics shared between different animals and which are exclusive to each species. This allows us to better understand human psychology and the world around us.
Within these investigations, more in the specific branch of social psychology and ethology, different human cultures, and those of other animals, are studied. But do other animals also have culture? Yes, much simpler, but yes.
Chimpanzees are the non-human species with the richest and most extensive culture. For this reason and their high similarity to humans, they have been one of the most studied animals in psychology. In this article I describe what chimpanzee cultures are like and the debate around cumulative culture.
What are the different cultures of chimpanzees like?
The first important thing is to define what we consider cultures: a stable set of characteristic and shared customs, ideas, social hierarchies, technologies, norms, skills and forms of communication by a social group. Among humans, there are cultural differences depending on the region in which we have grown up.
Well, the same thing happens with chimpanzees. Depending on the family or society in which chimpanzees live, there are differences in their skills, customs and technologies. These differences may be in terms of courtship methods, hygiene and grooming habits, places to establish their home…
But the majority of differences studied are in obtaining food and the instruments used for it. Some families of chimpanzees crack nuts with utensils to eat them, but each one does so with tools of different materials and sizes and even some who live nearby don’t.
This is just an example, but there are also differences in how they fish for termites with rods, how they hunt ants by submerging them in water, how they obtain honey using a stick… As for how these cultures are learned, there is quite a bit of controversy. It is known that it is not due to genetics, because they are all of the same species and there are even differences between families linked by blood.
In the case of humans, it’s pretty established by research: we have what’s called cumulative cultural transmission. On the other hand, as for chimpanzees, it is not so clear whether this type of cultural transmission occurs or whether it is simpler learning.
Cumulative culture: what is it?
We call cumulative culture the phenomenon by which skills and technologies are passed along through generations when they are learned socially. In this way, new ones are added, “accumulated” and the complexity and efficiency of existing ones are increasingly increased. This type of culture is characteristic of humans, and thanks to it we have a high degree of evolution.
The accumulation of skills and technology occurs thanks to social learning through imitation and the high-fidelity transmission of this knowledge. This type of learning happens when An individual sees a behavior of another being of the same species and decides to replicate it, assuming that it has a utility. Because of this principle, children often imitate everything their parents do.
On the other hand, improvement with the passage of generations happens because ideas to innovate techniques are more likely to arise if it passes through different minds, than if only a single individual has created it or tries to improve it. This produces the ratchet effect, whereby a skill or technology can only get better, but cannot get worse.
Debate around cumulative culture
After the definition of cumulative culture, the doubt arose as to whether cumulative culture is exclusive to human beings or, on the contrary, is shared with non-human species. Today this debate continues to exist, in which there are two points of view.
The first is that there are non-human species that also have a cumulative culture, such as some apes that have an extensive culture of skills and techniques. Specifically, there are studies that support that chimpanzees (our closest living relatives along with bonobos) learn to use tools through social imitation. This leads them to have the potential to create a cumulative culture.
ZLS: Chimpanzees do not have a cumulative culture
The other point of view defends that cumulative culture is exclusive to human beings. From this view, it is considered that The transmission of culture between the generations of these animals does not have that high degree of fidelity that characterizes cumulative culture.
This group supports the zone of latent solutions (ZLS) hypothesis. According to this hypothesis, cumulative culture produces what are called “culture-dependent traits,” that is, behaviors that can only be acquired through learning through social imitation, because they are too complex to occur to us spontaneously and individually.
Well, this hypothesis supports that in the culture of non-human apes, including chimpanzees, only “latent solutions” exist and there are no “culture-dependent traits.” Latent solutions are behaviors that are innovated individually, although they may sometimes be imitated by apes from the same culture.
However, these techniques and skills do not accumulate in the culture, but may be repeated only because another individual has had the same innovation or is imitating it. This happens because Their skills and technology are simpler and it is easier for different individuals to come up with them separately because the “solution” is actually already there, it is easy to imagine.
This is supported by some studies, with experiments called island tests or latent solution tests. They are experiments with chimpanzees in captivity without the ability they want to analyze, in order to evaluate whether certain behaviors can be invented by individuals, without the need to observe a model. For this reason, there are several studies that show that they can be reinvented.
Which side is winning in the cumulative culture debate?
In the last decade, there are several studies that disprove the hypothesis of the zone of latent solutions with complex behaviors of chimpanzees. I’ll tell you two of them that are especially interesting and representative.
In a recent study from 2022, an experiment was done in which a group of wild chimpanzees, who did not do the nut-cracking technique, were expected to acquire this behavior as a latent solution. However, No individual in the entire area managed to reinvent this technique within their family so it has not shown evidence in favor of the hypothesis of the zone of latent solutions.
Another study from the same research group in 2024, in this case with chimpanzees in captivity, taught a single individual in a group to open a puzzle to obtain food. It was expected that the rest of the chimpanzees in the group would learn from this chimpanzee by imitation, which happened after 9 months. They concluded that social learning is sufficient and necessary to acquire complex skills.
In conclusion to these theories, I would like to highlight that neither of the two theories can be accepted as absolute truth, since there is still not enough evidence to corroborate either. Therefore, this subject can be a relevant object of study for different behavioral and societal sciences, such as social psychology, sociology, anthropology or ethology.
