Lifespan Psychology in Great Apes: The Development of Tool Use

• Applicant: Sonja Ebel, Ph.D.
• Subject Area: Developmental and Educational Psychology ; Sensory and Behavioural Biology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 454726751

The field of comparative psychology studies the cultural differences and evolutionary origins of human cognition. It compares the cognitive abilities of humans from different cultures or humans and non-human primates to each other. A common problem with primate studies is that sample sizes are usually small (N<10 per group) and that the apes have a different age than the children (e.g., apes: 3-50 years, humans: 3 years). The age difference is problematic because one would also expect developmental trajectories for cognitive abilities in apes. In this project, I will bring together longitudinal and cross-sectional data to establish a comparative lifespan psychology. To do so, I will use data from nearly 20 years of research on great ape cognition from the Wolfgang Köhler Primate Research Center (Zoo Leipzig & Max Planck Institute for Evolutionary Anthropology). The apes regularly participate in cognitive (non-invasive) behavioral experiments. The data comprises 100 individuals from four great ape species (bonobos, chimpanzees, gorillas, orang-utans). The project focuses on the development of flexible tool use across the lifespan and its cognitive basis. Flexible tool use is a milestone in human evolution, and only few animals have the capacity for it. It allows an individual to adapt to diverse habitats and to exploit new resources. It is essential to study the cognitive basis of flexible tool use and the developmental trajectories of the underlying cognitive processes, because the same test results in young and old apes could be based on different processes (e.g., young apes potentially have better executive functions, whereas old apes have more knowledge by experience). Three key questions will be examined in this project: (Q1) How does an individual become a flexible tool user?; (Q2) What is the cognitive basis of flexible tool use?; (Q3) How does the social network influence the development of flexible tool use? The first two questions will be answered by using the experimental data from the published studies. Models will be formulated based on hypotheses, and then the data will be accumulated and analyzed. To answer the third question, video material will be coded that was collected each week from the apes in their social groups (‚focal observations‘). The behavioral data will be linked to the experimental data to examine the relationship between tool use and social dynamics. This project will establish the young discipline of comparative lifespan psychology in Germany. The longitudinal and cross-sectional data offer a unique opportunity to study developmental trajectories across the lifespan in four species of great apes. This data set is the only one of its kind. Since this project is unique, a significant output can be expected. The project faces low risks because the data has already been collected and is saved in an archive. This project has the potential to shape the field of comparative psychology substantially in the long run.

• DFG Programme: Research Grants