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New junior research group explores cooperative behavior

Which ecological and social factors influence group dynamics of chimpanzees and bonobos?
Chimpanzees maintain close social bonds within their group and collectively fight neighboring groups. Photo: Liran Samuni/Taï Chimpanzee Project
Dr. Liran Samuni beobachtet das Sozialverhalten einer Gruppe Bonobos im Kokolopori-Bonobo-Reservat in der Demokratischen Republik Kongo. Foto: Dr. Erin Wessling
Dr Liran Samuni observes the social behavior of a group of bonobos in the Kokolopori Bonobo Reserve in the Democratic Republic of Congo. Photo: Dr Erin Wessling
Dr. Liran Samuni ist seit Anfang Mai Leiterin der Nachwuchsgruppe „Kooperative Evolution der Primaten“ am DPZ. Foto: Karin Tilch
Dr Liran Samuni is head of the junior research group "Primate Cooperative Evolution" at the DPZ since the beginning of May. Photo: Karin Tilch

In the section Organismic Primate Biology, a junior research group led by the behavioral ecologist Liran Samuni started their work at the beginning of May. Their research is funded by the Emmy Noether Program of the German Research Foundation (DFG) for a period of presumably six years. The planned projects focus on social and ecological factors that influence the social dynamics and cooperation in chimpanzees and bonobos. More precisely, the researchers will initially explore three questions: How do environmental challenges and competition impact the survival and wellbeing of chimpanzees and bonobos? Do cooperation and innovation allow them to overcome these challenges? And how does environmental variation and competition between groups shape the social strategies of these two species?

Hormones and behavior
To approach these questions, Samuni and her team are planning comparative studies on free-living chimpanzees and bonobos. To do this, the researchers will observe the animals' behavior directly in the field and also evaluate footage from camera traps. In addition to the behavioral data, urine, faeces and hair samples will be collected for hormonal and genetic analyses. "I am particularly interested in linking behavioral data of social interactions with hormonal biomarkers," Samuni emphasizes. She hopes to uncover the underlying physiological processes that support cooperative and prosocial behavior among individuals within a group.

Barren savanna, lush forest
Samuni will undertake her first research trip from the DPZ in June: Her destination is a previously almost unexplored chimpanzee population in the savanna landscape of the Moyen Bafing National Park in Guinea. She suspects that the chimpanzees in Guinea cooperate particularly closely with their group mates and pass on cultural knowledge in order to survive in the savanna. For example, the juveniles learn to fish nutrient-rich algae from pools and streams with the help of processed stick tools. Chimpanzees in the rich rainforest of the Taï National Park on the Ivory Coast do not show such behavior. Now, for the first time, the behavioral strategies of chimpanzees in the savanna and in the forest will be systematically compared.

War and peace
Furthermore, there are plans to study wild bonobos in the Kokolopori Bonobo Reserve in the Democratic Republic of Congo. Unlike chimpanzees, bonobos are usually friendly towards neighboring groups and their territories overlap considerably. Sometimes even individual animals of both groups groom each other’s fur – this is a drastic contrast to the systematic warfare with fatalities among chimpanzees. However, unlike chimpanzees, bonobos are mainly restricted to densely forested areas with presumably high food availability and do not use tools for foraging. Samuni remarks: “With their different behavioral strategies, our closest living relatives provide us with a window into our own evolutionary past".