Understanding the emergence of behavioural and cultural diversity across the chimpanzee range
Group Leader: Prof. Christophe Boesch & Dr. Hjalmar Kühl
Over the last five decades, chimpanzees had been studied intensively at several long-term field sites. One of the major outcomes of this research was the documentation of a wide spectrum of behavioural and cultural diversity. In some populations, chimpanzees use for example sticks to fish for termites, combine hammer and anvil to crack nuts or use a set of branches and sticks to extract honey. What is puzzling about these observations is that not all populations use some food resources (termites, ants, honey, nuts etc.) in the same way, and with the same tools.
What are the factors, ecological or social, that influence the presence and form of such behaviours in chimpanzees? Similarly how does ecology affect social structure and grouping patterns?
Too many explanatory variables may play a role, including ecological differences, climate and weather conditions, historic effects and population dynamics, and that limits the explanatory value of the traditional approach with a limited number of long-term research sites. To overcome this strong limitation, we intend to use a wide spectrum of non-invasive techniques collected in a standardized and comparable way for 30-40 chimpanzee populations. Our techniques include camera traps for assessing local chimpanzee density, demographic and social structure, isotope analysis to assess hunting behaviour and nutritional status, genetics and a wide spectrum of ecological data collection related to plant, insect and prey resource availability.
Furthermore, such a more extensive approach will allow us to effectively discriminate between various explanatory hypotheses, such as
- Some chimpanzee populations have lost certain tool use behaviour in evolutionary times
- Behavioural and cultural diversity is a function of population size and connectivity
- Chimpanzee populations living in resource rich habitats tend to have a wider spectrum of cultural behaviour
- The frequency of hunting in a chimpanzee population is strongly dependent on the occurrence of suitable prey species