Multimodal signalling in wild and captive orangutans: redundancy versus complementarity

• Applicant: Dr. Marlen Fröhlich
• Subject Area: Sensory and Behavioural Biology ; Evolution, Anthropology
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 388558574

Animals communicate with con- and hetero-specifics using multicomponent signals in every sensory modality, employing visual, audible, olfactory and other signals. Despite growing evidence that the communication of nonhuman primates, our main model for the evolution of language, is intrinsically multimodal, most studies have focused on gesture or vocalization in isolation. However, why our closest living relatives should signal in single or multiple modalities is still poorly understood. So far we know very little about the function of multimodal signalling, and the evolutionary implications of the socio-ecological environment acting on communicative behaviour are poorly understood. Moreover, the ontogeny of multimodal signal production and perception is essential for an understanding of the proximate and ultimate mechanisms underlying communicative acts. Developmental research is however limited to multimodal signal perception, while signal production has been neglected. Given the growing evidence for a strong impact of social experience on communicative development, it is vital to understand the role of learning for multimodal signal production.The proposed project is designed to fill these gaps by examining how and why great apes use signal components of different modalities in intra-specific communication. In this study, I will for the first time systematically test the major competing hypotheses (‘backup signals’ versus ‘multiple messages’) in great apes. I will apply a multimodal-developmental approach to investigate function and ontogeny of multimodal communication in wild and captive orangutans (Pongo abelii/pygmaeus). Due to the orangutans’ intraspecific differences in sociability and their arboreality, I can examine to which extent social opportunities and ecological environment influence communicative behaviour. Specifically, I will investigate and compare the production of and responses to unimodal and multimodal signals in both species of orangutans in captivity and in the wild, allowing for the comparison between highly different social and ecological settings (2x2 comparison). In addition, I will compare the obtained results to corresponding data from the Pan species, chimpanzees and bonobos. With this threefold comparison (Borneo-Sumatra, Freiland–Zoo, Pongo-Pan), I can examine the extent to which the communicative behavior of great apes is linked to their socio-ecological lifestyle. In turn, this might provide novel insights on the evolution of human language as part of a multimodal system and the function of speech-accompanying signals like gestures, facial expressions and eye gaze.

• DFG Programme: Research Fellowships
• International Connection: Switzerland
• Host: Professor Dr. Carel P. van Schaik