How Humans Are Killing the Ingenuity of Chimpanzees
Cultures are indoctrination machines that teach us how to act in civilized society. For the most part, this is a great thing, especially when it pushes against some of our uncooperative and violent natural instincts. Cultures create many of the interesting irregularities that accumulate in human groups across the world. Some of us eat lahmacun rather than pizza, some of us speak Japanese rather than English, and some of us drive on the left rather than the right side of the road.
These differences are all examples of behavioral diversity, and this diversity emerges through learning and communication. When humans come together and target a common goal, they share their best ideas to improve their joint outputs. Today, the internet allows us to share ideas with people who live on entirely different continents. When we communicate our creative thoughts without diluting or compromising them too much, we contribute to expanding society’s problem-solving tools, and therefore enhance collective behavioral diversity.
In other words, when we communicate with people who have common interests, we end up developing and sharing new ways of manipulating the world around us. Every newborn doesn’t need to invent the wheel; they can simply be taught how to do it by previous generations, and then use their own creative mental energy to invent something entirely new. The more methods, strategies, and actions we accrue in our cultural toolkit, the more diverse our behavior becomes.
Behavioral diversity isn’t unique to humans. Chimpanzees, for example, also come up with intelligent strategies that help them forage and communicate more effectively. They then teach these strategies to other members of their social groups so that they can cooperate toward achieving shared goals. Chimpanzees can learn to throw stones to communicate, use sticks to eat ants from their nest, use stones to crack nuts, and even use chewed up leaves as a sponge for soaking up water to squeeze into their mouths.
Among non-human animals, the diversity in chimpanzee behavior is certainly remarkable and perhaps even humbling for humans to consider. But could the growing reach of humanity across the globe impact the behavioral diversity of chimpanzees? We already know that human intrusion can lead to declining numbers of particular species, and in some cases, even extinction. However, we don’t yet know how our intrusion may be changing the behavior and culture of animal groups.
As we speak, there are incredible worldwide conservation efforts that aim to prevent animal extinction and foster biological diversity. In combination with those efforts, it’s important to investigate any unforeseen consequences of environmental change that extend beyond population size. Biological diversity is important, but perhaps behavioral diversity also deserves our attention.
The end of March 2019 saw the publication of a Science paper analyzing the effects of human activity on behavioral diversity among chimpanzees. Researchers from around the world collaborated to understand whether human disturbances to chimpanzee communities, such as habitat loss and degradation, may lead to the decline of learned behaviors. When environments are split into fragments, it becomes harder for individuals within a group to share helpful behavioral strategies. That limited communication weakens the extent to which knowledge can be spread and strengthened.
The researchers monitored chimpanzee communities at 46 locations in Africa, across several months or years. They used cameras to study behavior, used fecal samples to examine ingested foods, and looked for artifacts of tool use scattered around the chimpanzee habitats. They also analyzed another 106 communities from existing studies on chimpanzee behavior to extend their datasets. What did they do with all this data? Their primary objective was to count how many learned behaviors — behaviors that spread culturally — they could find in each chimpanzee community.
To understand how the frequency of those learned behaviors might correlate with human activity, the researchers assessed the “human footprint” at each location: a composite measure made up of factors such as human infrastructure, population density, and the remoteness of the chimpanzee environments.
Chimpanzees living in areas with a large human footprint were 88% less likely to show learned behaviors than chimpanzees living in areas with a small human footprint. This general pattern held true regardless of whether the researchers looked at behaviors that required tools or merely ingenuity.
So the behavioral diversity of chimpanzees seems to take a hit as humans extend their reach further into wild environments. It’s not completely clear why this happens. It could relate to declining chimpanzee populations and weaker cultures for maintaining learned behaviors. Another possibility is that habitat loss blocks individual chimpanzees from spreading their message as far as they normally would in untouched territory. Or perhaps chimpanzees just get better at hiding their behavior and covering their tracks as human communities become more visible.
Chimpanzees and gorillas are both endangered, but conservation efforts continue to improve. When I visited Uganda and Rwanda in 2018, it was impressive to see the level of care and protection that some local organizations invested in keeping forest environments healthy, and wildlife safe. It pays to contribute to those efforts by visiting the countries and exploring the habitats for yourself with a dedicated guide.
Nevertheless, behavioral diversity is just one more problem for us all to worry about. Human impact doesn’t just slash population numbers, it may also reduce the quality of life for surviving animal communities. Imagine the dramatic drop in human quality of life if computers or engines suddenly disappeared from our communities. Chimpanzees may not have invented the internet yet, but losing tool skills and foraging wisdom may be their equivalent of losing the smartphone.
Our own lives may be impacting the lives of wildlife in ways we cannot fully appreciate. As we incrementally improve our knowledge about how human activity affects the climate and other organisms, we open up new opportunities to patch up the disastrous holes we leave behind. In addition to our existing focus on curbing extinctions and habitat destruction, it may be time to keep track of how human communities are subtly transforming the behaviors and cultures of fellow animals. It’s the only way to minimize the costs and externalities associated with the immediate flourishing of our own happy lives.