Commentary. The impact of humans on the environment is causing a loss of cultural diversity among chimpanzees, according to a new study. What can we learn from this?

The lost culture of the chimpanzees

Until quite recently, it was believed that only human beings developed a culture and passed it on from generation to generation. However, research by ethologists has shown that a number of animal species, even far removed from humans on the tree of life, possess cultural traditions and pass them on, and, in some cases, behave every bit like real teachers do.

Among the species that are able to develop local traditions are the chimpanzees, which are, together with bonobos, the species genetically closest to Homo sapiens. A study headed by zoologist Ammie Kalan of the Max Planck Institute in Leipzig, Germany, published in the latest issue of Science magazine, has shown that impacts from human activity are closely related to the disappearance of cultural diversity among chimpanzees.

But what is “culture” after all? To establish the existence of cultures in species other than ours, we need to find a fairly universal definition that we could also apply to monkeys, whales, birds or insects. For zoologists, culture means the transmission of customs, techniques and behaviors between individuals in a community who belong to the same generation and those who belong to subsequent generations. If we define it thus, culture is not something confined exclusively to humans: for instance, the use of sticks to catch termites among chimpanzees is a cultural tradition that members of a community learn from each other.

The most widespread mechanism for transmission is imitation: in most known cases, a new strategy spreads simply because individuals are copying behavior that appears to be beneficial. However, in some species one can find real “education”—meaning that individuals are able to adopt behavior that is disadvantageous to them in the short run in order to teach others a technique that, in the long run, will brings benefits to both student and teacher. This happens, for instance, with orcas that intentionally beach themselves in order to teach their young to hunt seals, or with cats who don’t kill their prey in order to let their young play with them. Among such animals, we often find some we don’t usually think of as having extraordinary intelligence: we find both cheetahs and bees among the ranks of animals who teach. On the other hand, species that are believed to be among the most “intelligent,” like chimpanzees, seem to rely exclusively on imitation.

However, it is not always true that the adoption of complex behavioral strategies is the result of “culture”: sometimes a new behavioral trait emerges through genetic means and is transmitted from one generation to another via DNA. Such a seemingly advanced task as the intentional cultivation of another species (which happens in some species of ants that grow fungi) can be passed on without any particular social learning mechanisms. For humanity, on the other hand, this was a very recent social achievement.

It is never easy to distinguish the genetic from the social component. One of the peculiarities of culture, however, is the existence of local traditions, customs and usages within one particular community that are not found in others, although they are genetically identical. Different clans of orcas make distinct sounds, comparable to our dialects, and have their own particular dietary preferences.

Similar things are happening among chimpanzees as well. In the aforementioned study, scientists at the Max Planck Institute surveyed 31 cultural traditions observed among 144 chimpanzee communities located in Central and Western Africa, in areas around the Equator. These involved various techniques useful to survival and thriving, such as the use of stones to break fruit shells, the making of sponges to extract water and drink it, the use of bathing or the shade of a cave to cool off in the summer, or building a bed of leaves for the night. Such customs are not present in all the communities of chimpanzees, but only in some of them. There are communities that use all of them, or nearly all, and others where certain of these customs are absent. Why is it that some communities appear to be culturally richer than others?

To understand this, the zoologists compared the cultural heritage of each community with the level of external impact on the environment in which the community lives. They found that the communities most affected by human presence are also the poorest in terms of cultural traditions. As is well known, human activity is eroding the most delicate ecosystems, especially in African countries with the highest population growth. As a result, between 1990 and 2014 the population of chimpanzees declined by as much as 80%, with an average annual decline of 6%. This has fragmented communities, hampered communications and hindered the spread of cultural traits across different communities.

Given the fact that the demographic decline of the great apes began a long time ago (it is thought that orangutans were driven out of Asia 30,000 years ago), the loss of cultural heritage could be very significant in explaining this process. As a remedy, scientists are now suggesting creating protected sites for the preservation of the cultural heritage of chimpanzees, and corridors of communication that would facilitate its spread.

After all, a similar process happened to people living in the West: the knowledge of the Greeks had been almost completely lost in the Middle Ages, and were recovered largely through the Arabic translations of the ancient manuscripts, copied by scribes in the monasteries.

Indeed, when it comes to learning, what is going on among great apes should also teach Homo sapiens a lesson: namely that cultural achievements, which include science and technology, are not acquired once and for all, and do not simply accumulate in a process of linear and infinite growth. On the contrary: when communities are fragmented and the ecosystem begins to deteriorate, material impoverishment and cultural impoverishment go hand in hand.

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