The GibbonFACS Project is a collaborative work conducted by researchers of the University of Portsmouth (UK), Freie Universität Berlin (Germany) and Duquesne University of Pittsburgh (USA). Video data was collected in different European Zoos. In collaboration with the Center for Digital Systems (CeDiS) from Freie Universität Berlin this Online Video Archiv was created.
The videos are provided with time-code based annotations. Facial expressions of the individuals were annotated using the Facial Action Coding System for hylobatid species (GibbonFACS). More information about this method can be found on: http://gibbonfacs.com/.
To understand human emotional expressions it is essential to investigate emotional expressions in animals using a cross-species approach. Given the strong association between facial movement and emotions, the aim of this project is to describe and classify facial expressions in gibbons and compare them with other great apes including humans.
Together with humans and great apes, gibbons belong to the primate superfamily Hominoidae (e.g. Geissmann 2002, Mootnick 2006). Among hominoids gibbons are the most diverse group with up to 16 species (Thin et al. 2010). Based on this special characteristic and their phlygenetic position between the great apes and Old World monkeys, gibbons provide a suited model for a multispecies comparative analysis in order to get new insight into the evolution and function of human and nonhuman primate facial expressions.
This video material of behavioural observations of five gibbon species (three genera), which was coded by the usage of a Facial Action Coding System for gibbon species (GibbonFACS – Waller et al. 2012). GibbonFACS is based on the anatomical dissections of gibbon faces (Burrows et al. 2011). We described the repertoire, the rate and the diversity of mimetic signalling and compared them between genera. We found a higher rate and diversity but no larger repertoire in Symphalangus compared to Hylobates and Nomascus.
Gibbons live in small family groups, usually consisting of one monogamous mated pair and their offspring. Recent observations in the wild found that the degree of monogamy between species can vary. Our aim was to explore whether the repertoire, rate and diversity of mimetic signalling in all five species correlate with socio-ecological factors like group size and degree of monogamy. We found no correlation of group size or of monogamy level with the three measurements.
Taken together, these results show that the genera of Symphalangus differ in some aspects of mimetic signalling from the genera Hylobates and Nomascus. However, the degree of sociality and monogamy of the observed species has no influence on the three important aspects of their signalling behaviour, namely the repertoire, rates and diversity.
Recording method
Focal observations (Altmann, 1974) of single individuals were conducted based on continuous (all occurrence) recording allowing the observation of social interactions between pairs of individuals. In this project we concentrated on situations in which the mated pair of a group (two adult individuals) interacts socially (social contexts; e.g. play, grooming, aggression, copulation etc.).
The total observation time contains ca. 21 hours. The total amount of video clips is 92 (mean recording time of each clip: ca. 15min.). We measured the following behavioural categories for each individual of the mated pair (N=16): Repertoire (all observed facial expressions), Rates of signalling, Presence of another individual except mated pair, Directedness of signalling and Context of signalling. We used Interact (company Mangold; video analysing software) to code the data.
References
Burrows AM, Diogo R, Waller BM, Bonar CJ, Liebal K (2011) Evolution of the muscles of facial expression in a monogamous ape: Evaluating the relative influences of ecological and phylogenetic factors in hylobatids. Anat Rec 294:645-663
Geissmann T (2002). Taxonomy and evolution of gibbons. In: Anthropology and primatology into the third millennium: The Centenary Congress of the Zürich Anthropological Institute (Evolutionary Anthropology Vol. 11, Supplement 1). Soligo, C.; Anzenberger, G. & Martin, R.D. (eds.), pp. 28-31, New York: Wiley-Liss.
Mootnick A R (2006). "Gibbon (Hylobatidae) species identification recommended for rescue or breeding centers". Primate Conserv 21: 103–138. doi:10.1896/0898-6207.21.1.103.
Van Ngoc Thinh, Mootnick AR, Geissmann T, Ming L, Ziegler T, Agil M, Moisson P, Nadler T, Walter L & Roos C (2010). Mitochondrial Evidence for Multiple Radiations in the Evolutionary History of Small Apes. BMC Evol. Biol. 10, e74.
Waller BM, Lembeck M, Kuchenbuch P, Burrows A, Liebal K (2012). GibbonFACS: a muscle-based facial movement coding system for hylobatids. Int J Primatol, DOI 10.1007/s10764-012-9611-6
