C4 Mia, a young bonobo female from the Fekako community, vocalizing in response to distant group members. Credit: Martin Surbeck, Kokolopori Bonobo Research Project.
Daily interactions are based on expectations, implicit rules and social categories that help us interpret other individuals' behaviours and coordinate our actions. Investigating how such social categories, norms and values contribute to social coordination is among the goals of The Normative Roots of Social Kinds — NORSK project, which is coordinated by the Department of Philosophy of the University of Milan and financed by the Italian Science Fund (FIS).
NORSK is an interdisciplinary project spanning across philosophy, cognitive science and empirical research. This is where Mélissa Berthet's work comes in. A researcher at the University of Milan, Ms Berthet has studied communication in primates for a long time and was even interviewed by CNN about her field research on bonobos in the Democratic Republic of the Congo, where she sought to understand how signals, expectations and interactions contributed to inter-individual coordination. Her work observing primates will be one of the core contributions of the new project of the University of Milan.
"Humans are just one of the many social species on Earth," explained Francesco Guala, Professor of Political Economy and Principal Investigator of the NORSK project. "NORSK aims, among other things, to investigate the communication mechanisms used by certain non-human species to develop forms of cooperation based on normative mechanisms. Mélissa Berthet's work is part of this line of research."
"Mélissa's research on how gorillas signal their commitment within joint actions will enable us to identify the basic mechanisms that we share with other species, and, at the same time, to understand which abilities are a distinctive feature of humans," added John Michael, Professor of Logic and Philosophy of Science at the University of Milan.
We recently interviewed Mélissa Berthet, who has also been selected as a finalist for the Coller-Dolittle Prize, to learn more about her observation of bonobos in the Democratic Republic of the Congo.
Tupac, a young male bonobo scratching its head. Lukas Bierhoff, Kokolopori Bonobo Research Project.
How was the work carried out in the Democratic Republic of the Congo to record bonobo calls, and how long did the fieldwork last?
I conducted my research at the Kokolopori Bonobo Research Project in the Democratic Republic of the Congo, a long-term field site where three bonobo communities have been habituated to human observers. What makes Kokolopori particularly interesting is that the project was initiated and is still strongly supported by local communities, who began habituating the bonobos around 15 years ago. Thus, the bonobos we study are habituated, which means that researchers can observe natural behaviour at close range without disturbing the animals. Overall, we do not interfere with the animals at all (i.e., no feeding, no touching, limited gaze interactions, we remain silent as much as possible etc.) so that we do not disturb them. The point is to try as much as possible to make them forget that we are here so that we can observe behaviours that are as natural as possible.
In total, I spent about eight months in the Congo working alongside both local assistants and international researchers. The field site is extremely remote: after flying to Kinshasa, we took a small charter plane to a regional town, drove a motorbike for about six hours to the nearest village, and then walked for an hour through the forest to reach camp.
What was a typical field day like?
A typical field day started around 3:30 or 4:00 am. We would walk between 30 minutes and two hours to reach the bonobos before they left their sleeping nests. We then followed them throughout the day until they built new nests in the late afternoon, usually around 4:00 or 5:00 pm. Depending on the day, we could walk 15–20 kilometres through the forest while observing them.
We lived in a simple camp in the middle of the rainforest, sleeping in tents and relying on solar panels to power our research equipment. There was no mobile phone coverage or Internet access. We would shower in the river and drink filtered river water. Food was prepared at camp mostly from local ingredients — anything more industrialized had to be brought by plane, and given that charter planes only fly every 2-3 months to there, we did not really have basic western food — aside from pasta, which we could eat about once or twice a week!
How did you collect and analyse bonobo calls?
Collecting data on wild bonobos is extremely challenging. To maximise the number of vocalisations I could collect, I carried a microphone throughout the day and recorded continuously. One difficulty is that bonobos can remain silent for hours and then suddenly produce vocalisations in a chorus, with several individuals calling all together. This makes it difficult to identify which individual produced which call. As a result, some days after 8–12 hours in the forest, I would return to camp with 50 recorded vocalisations, while on other days I might come back with none at all.
Whenever I was able to record a vocalisation and confidently identify the caller, I described the context in as much detail as possible by saying out loud everything into the microphone I observed around the individual at the time of the call. Because bonobos typically spend much of their day in relatively small groups of six to eight individuals, it is often possible to observe most ongoing social interactions, although this requires extensive training and good observation skills.
After returning to camp, I processed the recordings. This work was also extremely demanding: for two days of data collection with the bonobos, I needed at least one full day of data processing at camp. This involved locating the good-quality vocalisations in the very long recordings. For each call, I then coded its context of emission by answering more than 300 questions. These included actions from the caller (e.g., whether the caller was feeding, grooming, travelling, interacting with another bonobo), reactions from the other bonobos (what they started, kept or stopped doing), and external events (e.g., the presence of prey, rain, other animals etc.). This contextual information was extracted from the verbal notes I had recorded in the field.
How was the large amount of data managed?
We collected about 1,000 vocalisations of bonobos, which we then analysed once I returned to the University of Zurich. In particular, I conducted statistical analyses to find whether some vocalisations were systematically associated with one or several contextual parameters. This allowed me to determine, for each call type of bonobos, what happens when this vocalisation is emitted, i.e., what the meaning of this vocalisation is.
Gorilla group: Credits: Martha M. Robbins/MPI-EVA.
Are there any initial results on the social dynamics of bonobos?
I don't work on social dynamics. However, I can tell you a bit more about my past research.
Last year we published an article on the vocal communication of wild bonobos, which has been selected for the Coller-Dolittle Prize (hence the media coverage). The Coller-Dolittle Prize is an international scientific initiative that offers up to 10 million dollars to anyone who can develop a system to decipher and translate communication between humans and animals. In a nutshell, we have shown that the calls of bonobos have meaning, and that they can combine them in sequences that look like human sentences. This suggests that the ability to construct complex meanings from smaller vocal units was already present in our ancestors at least 7 million years ago, if not earlier.
How does your work contribute to the NORSK project?
Within the NORSK project, I will investigate joint commitment in wild mountain gorillas. To study this, I will conduct fieldwork in Uganda's Bwindi Impenetrable Forest, which is home to around half of the world's mountain gorilla population. There, I will collect detailed behavioural and communication data, including vocalisations, gestures, facial expressions, and body postures. In particular, I will film gorillas during joint activities and analyse whether they communicate to initiate or coordinate these activities.
My contribution to the project builds on more than 13 years of experience studying communication in wild primates. I have conducted fieldwork on several species, including howler monkeys in Mexico, titi monkeys in Brazil, and bonobos in the Democratic Republic of the Congo, spending a total of around three years collecting data on wild primates in remote field sites. This expertise is essential for investigating how gorillas coordinate their behaviour and whether they exhibit joint commitment. The gorilla research is conducted with the long-term gorilla project of the Max Planck Institute for Evolutionary Anthropology.
Potrebbero interessarti anche