The Complex Social Nature of Chimpanzees

Hello to all you chimpanzee enthusiasts! We’re back with another article to talk to you about chimpanzees and their social lives! When it comes to the importance of sociality, chimpanzees are no less dependent on their friends as we are. That being said, there are some clear differences between humans and chimpanzees and the ways in which we live our social lives. Today’s article will look at those two sides of the coin in more detail.

For decades, scientists have debated on the subject of chimpanzee mental capabilities and to what extent they may possess theory of mind (Gallup, 1970). Theory of mind is an important social-cognitive skill that involves the ability to think about mental states, both of the self and of others. A recent study in the journal PNAS (Proceedings of the National Academy of Sciences) titled “Great apes use self-experience to anticipate an agent’s action in a false-belief test”(2019), is an important advance in efforts to determine to what extent our closest relatives can understand others’ perspectives. Indeed studying this topic in chimpanzees also helps to clarify which aspects of the human mind were already present 6-9 million years ago in our common ancestor and which evolved uniquely in the human lineage after the divergence from the other apes. There have been many such studies that have attempted to investigate similar topics, however all of these take place in captive settings where chimpanzees, though they may live long healthy lives, are ultimately not exposed to their natural, innate settings in which their brains and bodies were adapted for. Answering these questions in a natural setting is close to impossible because there are too many factors to control and the ethical questions that arise are numerous and indeed valid. In the wild however, over many decades of behavioral research, scientists have learnt much about our closest living relatives just by watching them go about their daily lives. We are constantly learning and discovering new information about the ways in which chimpanzee society functions and the way in which the chimpanzee mind works in their natural habitats. Chimpanzees are now well known for their cooperative skills, these are most notably observed in group hunting, territory defense and the formation of alliances (Boesch, 1994).

Another one of the many interesting topics of social cognition is social learning. Defined simply it is the ability to transfer information between individuals. In humans social learning has led to a diverse cultural world. Do you think our non-human primates have culture as well? This question has been a hot topic of debate for the past decades among primatologists, psychologists and anthropologists alike. The main findings are that even if not as starkly diverse as human culture, there are clear site-specific and even multi-generational “traditions” in chimpanzee populations. These cultural variations pertain to some of the first observations made by Jane Goodall herself. Some examples of current differences researchers have identified are: tool use, aimed throwing, nest building, grooming, rain dancing and courtship rituals. Differences can also mean a complete absence of a certain type of behavior amongst separate chimpanzee populations or even communities. One of the most interesting findings has been that chimpanzees belonging to one community sometimes develop different behavioral patterns from their neighboring communities even when they share the same habitat and have access to the exact same materials (Luncz et al., 2012). This in some cases could be due to “lessons” between mother and offspring, teaching the ways of the community. However chimpanzees learn all throughout their adolescence from all group members. To finish up the short briefing on chimpanzee culture we want to provide you with one more “hands-on” example. An interesting study studying one community of chimpanzees in the Kibale forest in Uganda showed that chimpanzees there use sticks to extract honey from a log whilst individuals in the Budongo forest of Uganda only 200km away use chewed up leaves as “sponge-like” tools to extract the sweet honey from logs (Brunette, 2020).

Chimpanzee Eating Tortoise (Site-Specific Behavior)

Now we will dive deeper into another aspect that is important and vital for social relationships to form and develop: Emotions. Emotions are said to be indicated via facial expressions (Ekman & Friesen, 1971). These expressions carry a variety of information about motivation and intention. In humans the study of and effort to make sense of these facial expressions has spanned decades (Ekman, 1997). Scientists have now even created a pretty impressive tool for facial coding for Chimpanzess called ChimpFACS, which can be used as a tool to help us understand them better. Identifying prototypical expressions can help propel the research of chimpanzee social cognition as it can provide a standard for scientific work (Parr et al., 1998). Nonetheless, there is still a major problem to get photographic data of emotional expressions as the situations they occur in are highly charged and involve fast movements. However despite these hurdles, research into emotions and social phenomena is producing interesting findings. For example, using these tools researchers have quantified chimpanzee empathy, showing that individuals look out for one another and provide help when needed. An example of this in a captive setting is at the Tchimpounga Chimpanzee Rehabilitation Centre where female chimps have been known to adopt orphaned infants. This also takes place in the wild, at Tai Chimpanzee Project in Cote d’Ivoire there is the amazing story of adult male Fredie and his band of orphans that he cared for and protected, most into adolescence. On a final note, it is important to note that chimpanzees who are deprived of social interactions or their normal living environment often succumb to depression and other negative emotional states. Though sanctuaries around the world do their best to create healthy living environments for chimpanzees, the best place for a chimp is in the wild where they belong.

Now that you know a bit about the mental and cultural capabilities of chimpanzees let’s take a look into social structure and the story behind hierarchies! Be warned the social structures of chimpanzees are not as simple as they appear and can sometimes even seem as interwoven as those in Game of Thrones (disclaimer: do not take this comparison too literal). Indeed the mixture of friends, foes, community and power dynamics at play make for a lot of interesting phenomena to study and understand.

Let's start at the top of the ladder - with the alpha-male. Becoming the alpha-male in a group does not come with a simple guaranteed approach, but rather it depends on the personality of the individual chimpanzee and the standing of that chimpanzee's mother throughout his life. However what most alpha-males do have in common is a strong coalition with other subordinate chimpanzees. These other individuals are vital in helping him both gain and then maintain the power he possesses. These allies can be playmates from juvenile years, brothers or even “new” friends looking to increase their standing in the group. Sometimes however there are new coalitions formed to overthrow an old leader. Much of a chimpanzee male’s life is dedicated to climbing up or being knocked down the chimpanzee social ladder (read about the ‘Fall of Ferdinand’ here). All in all it's an ever changing power struggle, and some of the most exciting moments to watch in chimpanzee society are when places on the hierarchy are challenged (Brittany Cohen-Brown, 2018).

Now what about female chimpanzees? How do they fit into the hierarchy? First of all, it's important to know that there is also an alpha-female. A major difference between male and female alphas is that females aren’t as likely to use aggression and violence to get to their goals. They rather prefer to use long-time relationships and personality traits to either maintain their place or gradually move up the hierarchy. However, this is not to say it's all calm and peaceful, female chimpanzees are capable of using their force, especially when displeased by lower-ranking females. One major benefit being the female alpha is that she is more likely to be more successful when it comes to reproduction and access to food. As mentioned before the offspring of higher-ranking females tend to achieve a higher status themselves than chimps born to lower-ranking mothers (Brittany Cohen-Brown, 2018).

Another interesting piece of information about chimpanzees is that they do not have nuclear families but are rather promiscuous. This comes with a certain advantage: Not being able to know who the father is. This reduces stress that females and their children are faced with and serves as an indirect protection for them. However in very rare cases in intra-community settings do male and sometimes even female chimpanzees kill the offspring of others, due to rivalry (males) or food competition (females). Another thing to note is that male chimpanzees stay in their natal community for their whole life, while females tend to leave and join other communities around puberty (de Waal, 2005).

As we are talking about males and females now let's quickly take a look at “parenting”. Firstly, it should not be understood in the same way that we humans see parenting. For the most part male chimpanzees are not involved in raising the offspring. This is due to the promiscuous dynamics in a community mentioned above. Yet, interestingly more recent studies that can identify paternity in the group show that some fathers seem to be able to identify their offspring and behave in a somewhat positively biased way towards them (Murray et al., 2016). However, the origins of that are not fully understood by research as of now. In general, mothers do all of the hard work! When it comes to mother-child relationships there are different degrees of parental care and mothering styles, comparable to us humans. Some mothers are very protective and others are more relaxed.

Mother and Child

With that all being said, let's take a look into one of the more sinister social aspects of chimpanzees by investigating a phenomenon that was once thought to be uniquely human – war. This phenomenon is common in all communities of chimpanzees that have neighbouring communities. There are several reasons that these aggressive interactions may occur or increase: territory defense, competition for food or territory, predation and more. One famous instance of this is the “Gombe War'' that waged for four years in the 1970’s. It commenced with the death of the original alpha-male which then split the community into two groups the “North” and the “South”. The larger of these two groups then began to invade the territory of the others - if and when they found a rival they attacked him and left him to die of his wounds. Ultimately, this led to the annihilation of the entire group.

Even rarer than this is interspecies violence. Here at Loango the first two observations of two separate encounters between chimpanzees and gorillas were made in 2019. In both situations the chimpanzees outnumbered the gorillas and instigated the attacks. The result: two infant gorillas were killed. What caused this outburst of violence against the gorillas? We assume that it might be due to interspecific competition, or the possibility that the infant gorillas were seen as prey or even that the chimpanzees saw the gorillas as intruders much in the way they view neighbouring chimpanzee groups. If you are interested in more information on that feel free to take a look at our publication in Nature: https://www.nature.com/articles/s41598-021-93829-x

We hope that all this information gives you a rough idea of how interesting and complex research into chimpanzees and their social structures is and how surprising some observations can be. Also, there is much uncharted territory still left to explore!

Thats all we have for you today. Stay tuned for upcoming articles!

Best wishes

The Ozouga-Blogging-Team

References:

1. Gallup, G. G., Jr. Chimpanzees: Self-recognition. Science 167, 86-87 (1970)

2. Kano, F., Krupenye, C., Hirata, S., Tomonaga, M., & Call, J. (2019). Great apes use self-experience to anticipate an agent's action in a false-belief test. Proceedings of the National Academy of Sciences of the United States of America, 116(42), 20904-20909. https://doi.org/10.1073/pnas.1910095116

3. Boesch, C. Cooperative hunting in wild chimpanzees. Animal Behavior 48, 653-667 (1994).

4. Luncz, L., Mundry, R., & Boesch, C. (2012). Evidence for Cultural Differences between Neighboring Chimpanzee Communities. Current Biology, 22(10), 922-926. doi: 10.1016/j.cub.2012.03.031

5. Matt Brunette, JGI Canada Volunteer (2020, June 9). Do Chimpanzees Have Culture? Jane Goodall. https://janegoodall.ca/our-stories/chimpanzees-and-culture/

6. Ekman, P., & Friesen, W. V. (1971). Constants across cultures in the face and emotion. Journal of Personality and Social Psychology, 17(2), 124–129. https://doi.org/10.1037/h0030377

7. Ekman P. Should we call it expression or communication?. Innovations in Social Science Research, 1997, vol. 10 (pg. 333-44)

8. Parr LA, Hopkins WD, de Waal FBM. The perception of facial expressions in chimpanzees (Pan troglodytes), Evolution of Communication, 1998, vol. 2 (pg. 1-23)

9. Cohen-Brown, B. (2018, July 11). From Top to Bottom, Chimpanzee Social Hierarchy is Amazing! Jane Goodall’s Good for All News. https://news.janegoodall.org/2018/07/10/top-bottom-chimpanzee-social-hierarchy-amazing/

10. de Waal, F. A century of getting to know the chimpanzee. Nature 437, 56–59 (2005). https://doi.org/10.1038/nature03999

11. Murray Carson M., Stanton Margaret A., Lonsdorf Elizabeth V., Wroblewski Emily E. and Pusey Anne E. 2016 Chimpanzee fathers bias their behaviour towards their offspring, R. Soc. open sci.3160441160441

12. https://releasechimps.org/chimpanzees/intellect-and-emotion

13. http://www.conservenature.org/learn_about_wildlife/chimpanzees/chimp_mothering.ht

Healthcare in Chimpanzees

There’s an old saying: Health is wealth! No doubt this holds true for each and every living species on the planet. With the recent classification of chimpanzees as endangered species, it goes without saying that healthcare plays a vital role in the survival of the species. So, in today's article let’s dive into the topic of Healthcare in Chimpanzees! We will ask some important questions such as: What are the reasons for the rise in their mortality rate? Did the global pandemic affect one of our closest living relatives as much as it did affect us? Do chimpanzees self-medicate in ways similar to humans? And finally what are the guidelines followed in our field site to protect the health of our special chimpanzees.

There are different causes for the increase in the mortality rate of chimpanzees, including natural causes of death, such as illness, intercommunity encounters, and intraspecific aggression which fluctuate at natural levels across time and field sites. Nevertheless, they are connected to habitat loss and poaching pressures which are intensified or more frequent due to knock-on effects mainly from a lack of space or resources. Overall, most chimpanzees still die due to natural onset illness. It is the most common cause of death, through all ages and sexes with respiratory illness causing the highest mortality (Williams and colleagues, 2008). It is important to note however that anthropogenic pressures can introduce novel strains of a virus or a new bacteria that chimpanzees cannot naturally combat. Another cause of death in infant chimps is when their mother dies. Then their chance of survival is also very low. (Williams and colleagues, 2008).

Intercommunity aggression has the greatest impact on male adults and both male and female infants (Mitani and colleagues, 2010). In these intercommunity aggressions, individuals eventually die usually due to sustained injuries. Furthermore, poaching is one of the most prominent threats for chimpanzees across Africa. While the presence of researchers reduces this threat, it can at the same time increase the risk of human-to-ape transmission of diseases (Köndgen and colleagues, 2008).

The ongoing pandemic has a major impact on humans, but how has it affected our closest living relatives? Can SARS-CoV-2 also be a threat for them? The answer is: Yes! Since there is close contact between humans and habituated apes there is a high potential for the transmission of diseases. Not only can this happen because of research groups, but also through tourism and poachers. This is a dilemma as "Great Ape Tourism" is an important source of income in some African countries. The reduction of this could limit the funding towards healthcare and support of chimpanzee lives. Furthermore, the presence of researchers has a strong positive effect in suppressing poachers (read our "Research means Protection" article to dive deeper into the topic). In Loango, we take extensive measures to protect and care for the health of chimpanzees.

Well! On the positive side, it’s not all bad news. It has been hypothesized that much of human’s traditional knowledge stems from our ancestors observing the medicative behaviors of non-human animals. Chimpanzees are just one example of a species that has been shown to self-medicate (Huffman and colleagues, 2001), they do so by making use of the natural resources in their habitats. This behavior is known as zoopharmacognosy (Daoudi, S., 2016). The two most notable types of this self-medicative behavior observed in the wild are leaf swallowing and bitter pith chewing. These behaviors were first observed at the field sites, Mahale and Gombe in Tanzania, and Kibale in Uganda (Huffman and colleagues, 2001). The first observation in 1983 that left the scientists puzzled was the swallowing of the Aspilia spp. leaves. It was intriguing to them because this leaf species lacked any nutritional value in their diet (Wrangham and colleagues, 1983). It was not until 1996, that this behavior was discovered to be associated with self-medication as a means to expel parasitic worms via their feces (Huffman and colleagues, 1996). The chimpanzees were swallowing the leaves to take advantage of their rough and bristly surface that hooked onto the worms as the leaves passed through their digestive system, in turn purging their intestines of certain parasites. Furthermore, the chewing of the bitter pith of Vernonia Amygdalina became known as a clear indication of poor health, as also evidenced by diarrhea, lethargy, weight loss. It was shown to combat nematode worm infection. From a study by Huffman and colleagues (2001), that recorded two cases in detail, recovery from such symptoms was evident 20–24 hours after the chimpanzees chewed the bitter pith. The plant species used for these medicative events vary in form (herb, vine, shrub, and tree), but the common property functionally linking all of these forms is their bristly, rough-surfaced leaves. An individual may swallow anywhere from one to 56 leaves in one bout.

Vernonia Amygdalina

Aspilia

Image Sources: João Medeiros & Forestowlet

Now, how do humans factor in? In our ever-changing world, humans and non-human animals are coming into contact ever more frequently. The majority of these interactions are negative and often result in losses to the non-human animal side. In regards to chimpanzees and the other African apes, these populations are becoming ever more threatened by encroachments from human development and the subsequent pressures this places on an environment. However, there are now a number of specific research and tourism guidelines that have been implemented to protect the health and safety of great-apes under these conditions. At the Ozouga study site, we actively enforce hygiene measures and follow the "IUCN Best Practice Guidelines for Great Ape Tourism" (2010) even though at present our community is not exposed to tourist visitors. These regulations apply to research sites globally that work with great apes and provide advice on how to ethically interact in these shared environments. The most important rule when it comes to interaction with non-human great apes is - distance! As a rule of thumb, our interference with their daily lives is always kept to the bare minimum. Further, there must always be a minimum distance of eight meters between the researchers and the chimpanzees (we have been practicing maintaining distance long before it was necessary for the current COVID-19 pandemic health and safety measures!). The second most important rule is the mandatory use of surgical face masks. Chimpanzee research and tourism projects have documented known human pathogens like human respiratory syncytial virus (HRSV), the human metapneumovirus (HMPV), and the human rhinovirus C, that can cause mortality in wild chimpanzees. The wearing of surgical face masks is feasible, inexpensive, and has been shown as an effective barrier to exhaled pathogens.

In addition to these enforced rules, another important aspect of working around chimpanzees is, following basic hygiene practices. In 2017, a ‘Hygiene Barrier’ was built at our research camp to serve as a transition point between the camp and our daily work in the forest. All our fieldwork clothes and equipment are stored in the hut, and everyone is required to change before entering the camp after a day of long work in the forest. Hand washing and the use of sanitizers is a common affair all throughout the day. Furthermore, there are strict rules about what can be left in the forest. For example, fecal matter cannot be left in the forest and must be transported hygienically back to the camp where it will be disposed of in a safe way. Additionally, all staff members and individuals who may potentially come into visual contact with chimpanzees must be healthy and have no symptoms of the disease such as a fever or a runny nose. If any member of the team becomes sick they quarantine themselves until no longer contagious and in serious cases leave the camp immediately.

Our Camp

Fieldwork

In the past years, a long-term health monitoring system has been implemented for all of our habituated community members. On a daily basis, the health conditions of the individuals are recorded and monitored for any signs of illness such as sneezing, coughing, or excessive diarrhea. The healing process of wounds when individuals become physically injured is also carefully monitored. In cases where an individual is observed showing symptoms of illness we follow this individual closely to monitor the progression of these symptoms and collect extra samples including urine, fecal, and blood matter when possible. This system allows us to create a database for monitoring the general health of the Rekambo community.

So far we have discussed all that is done to take care and protect our Ozouga Chimpanzees to the best of our abilities. Is there something that you, the general public, can do? Of course! You can share our objective and support us on our journey, to raise public awareness about our endangered relatives. We also very much appreciate any financial support to continue our efforts in the protection and conservation of this endangered species. If you’d like to join our cause you can donate to the Ozouga fund.

That’s all for today, we hope you enjoyed it!

Yours sincerely,

The Ozouga-Blogging-Team

References:

1. Daoudi, S. (2016, June 2). How other primates self-medicate – and what they could teach us. The Conversation. https://theconversation.com/how-other-primates-self-medicate-and-what-they-could-teach-us-59869

2. Wrangham, R.W., Nishida, T. Aspilia spp. Leaves: A puzzle in the feeding behavior of wild chimpanzees. Primates 24, 276–282 (1983). https://doi.org/10.1007/BF02381090

3. Huffman, M.A., Caton, J.M. Self-induced Increase of Gut Motility and the Control of Parasitic Infections in Wild Chimpanzees. International Journal of Primatology 22, 329–346 (2001). https://doi.org/10.1023/A:1010734310002

4. HUFFMAN, M. A. (2001). Self-Medicative Behavior in the African Great Apes: An Evolutionary Perspective into the Origins of Human Traditional Medicine. BioScience, 51(8), 651. https://doi.org/10.1641/0006-3568(2001)051

5. Köndgen, Sophie et al. “Pandemic human viruses cause decline of endangered great apes.” Current biology : CB vol. 18,4 (2008): 260-4. doi:10.1016/j.cub.2008.01.012

6. Williams, J M et al. “Causes of death in the Kasekela chimpanzees of Gombe National Park, Tanzania.” American journal of primatology vol. 70,8 (2008): 766-77. doi:10.1002/ajp.20573

7. Mitani, J. C., Watts, D. P., & Amsler, S. J. (2010). Lethal intergroup aggression leads to territorial expansion in wild chimpanzees. Current Biology, 20(12), R507–R508. https://doi.org/10.1016/j.cub.2010.04.021

8. Best practice guidelines for great ape tourism | IUCN Library System. (2010). Best Practice Guidelines for Great Ape Tourism. https://portals.iucn.org/library/node/9636

Why Research Means Protection!

Chimpanzees (Pan troglodytes) are amongst our closest relatives, sharing roughly 98% of our genetic code. Unfortunately, our relatives are dying at a rapid pace, with estimates suggesting that the number of chimpanzees left in the wild is between 170,000 - 300,000 and those counts are dropping.

Concerning the most prominent threats to the species, the majority can be traced back to a singular infamous species, Homo sapiens. The threats imposed by humans on chimpanzees are manifold; Poaching, loss of habitat, and (human-spread) diseases are currently the most severe.

Unfortunately, combating these threats is not as straightforward as it seems. The areas in which humans and wildlife, namely great Apes, live in close proximity, are often areas plagued by a lack of access to education and lower economic margins. This means that local populations become desperate and must search for other ways in which to provide for their families and communities in this ever-changing world.

Luckily, as it turns out, there seems to be another promising action that can help drive the fight to help chimpanzees: RESEARCH!

Various past studies suggest that the presence of researchers and research camps in wild areas can have a positive impact on wildlife stock. Pusey et al. (2007) for example present at least four distinct benefits Research has provided at Gombe National Park, Tanzania.

1. It was due to Jane Goodall’s groundbreaking research that showed us the urgent need to protect chimpanzees from extinction, and attention was drawn to the field site. This eventually resulted in Gombe being declared as a national park, with all of the environmental benefits for the ecosystem and its inhabitants.

2. Her findings also drew worldwide public attention to Gombe and Tanzania. Attention from tourists and donors who provide financial support for the region, the parks, and chimpanzee conservation in general.

3. The on-site research delivered crucial information on social structures and habitat use which is essential for effective chimpanzee conservation at Gombe and elsewhere.

4. Their research allowed a detailed tracking of the local chimpanzee population over time and helped to identify the chimpanzees' greatest threats.

Furthermore, another study showed that research presence seems to have a strong positive effect on the suppression of poaching in the area surrounding a research station (Köndgen et al. 2008).

As you can see, the effects of research tackle 2 out of the 3 main threats for chimpanzees, namely poaching and habitat loss. Unfortunately, on-site research, as well as ape tourism, increase the third major threat, the transmission of human diseases, since both inevitably bring humans and chimpanzees closer to each other (Köndgen et al 2008) - often with fatal consequences for chimpanzee communities.

We need to question whether the risks of research (and ape tourism) may outweigh the benefits. It was due to research that this threat was discovered and it is due to research that we may now find new ways to tackle these threats. For example, Köndgen et al. (2008) suggest controlling the human-ape interactions in ways that significantly decrease the risk of disease transmissions, such as the obligation for all humans to keep a safe distance when observing wild chimpanzees and always wear face coverings (surgical masks) when in proximity to the chimpanzees (something we are now more used to, thanks to 2020!)

Research provides knowledge and is arguably one of the most effective tools to help humans find solutions to problems. Knowledge enables education and education in turn can also leverage chimpanzee protection. This is why research means protection!

References

Köndgen, S., Kühl, H., N'Goran, P. K., Walsh, P. D., Schenk, S., Ernst, N., ... & Leendertz, F. H. (2008). Pandemic human viruses cause decline of endangered great apes. Current Biology, 18(4), 260-264.

Pusey, A. E., Pintea, L., Wilson, M. L., Kamenya, S., & Goodall, J. (2007). The contribution of long‐term research at Gombe National Park to chimpanzee conservation. Conservation Biology, 21(3), 623-634.

The IUCN Redlist, https://www.iucnredlist.org/species/15933/129038584