Adrian Soldati

Research interests

Vocal communication, evolution of language, vocal development, social behaviours, primatology.

Research project

How do our closest living relatives, the chimpanzees, learn to communicate with each other? How flexible and socially mediated is their vocal development and behaviour?

The main aim of my PhD project was to investigate the ontogeny of pant-hoots, a multi-phase vocal sequence typically used to maintain contact and coordinate movements between individuals and groups over long distances. The question of how this complex and flexible vocal signal develops is key for a better understanding of how chimpanzees navigate dynamic social interactions in fission-fusion societies from both an ontogenetic and a comparative perspective. I focused on how the ontogeny of vocal production, usage, and comprehension are affected by individual and social factors in immature individuals. I collected data on the chimpanzees of the Sonso community living in the Budongo forest (Uganda).

Results from my thesis show that chimpanzees produce rudimentary pant-hoot sequences since birth, suggesting that vocal repertoires are largely innate. However, these sequences presented some structural and acoustic differences when compared to those of older individuals, suggesting they also undergo ontogenetic changes. In immature chimpanzees, behavioural and vocal responses to others’ pant-hoots was enhanced by greater vocal and social exposure to key group members, such as the mother and adult males, when compared to the development of less gregarious immature individuals. In adult chimpanzees, social context modulated the use of pant hoot phases during vocal displays, likely enhancing the communicative capacities of a species with limited vocal production learning and relatively small vocal repertoire. Taken together, findings from my thesis suggest that the ontogeny of complex chimpanzee vocalisations is socially mediated and that chimpanzee vocal communication is flexibly adjusted depending on the social environment.

During my PhD, I also adopted different methods of data collection, including novel infrared thermography and playback experiments, combined with natural observations. The ultimate goal of my study is to provide new insights in the domain of non-human primate communication as well as in the emergence and evolution of human language using a comparative approach. My research project was a cotutelle between the University of Neuchâtel and the University of St Andrews. My supervisors were Prof Klaus Zuberbühler and Prof Josep Call. Previously, I worked on gestural and multi-signal communication in the Waibira and Sonso chimpanzee communities with Dr Catherine Hobaiter (University of St Andrews).

Publications

2023. Badihi, G., Graham, K., Fallon, B., Safryghin, A., Soldati, A., Zuberbühler, K., Hobaiter, C. Dialects in leaf-clipping and other leaf-modifying gestures between neighbouring communities of East African chimpanzees. Scientific Reports. https://doi.org/10.1038/s41598-022-25814-x

2023. Jiang, Z., Soldati, A., Schamberg, I., Lameira, A. R., & Moran, S. Automatic Sound Event Detection and Classification of Great Ape Calls Using Neural Networks. arXiv (preprint). 10.48550/arXiv.2301.02214

2022. Péter, H., Laporte, M., Newton-Fisher, N. E., Reynolds, V., Samuni, L., Soldati, A., Vigilant, L., Villioth, J., Zuberbühler, K., Hobaiter, C. Recognition of Visual Kinship Signals in Chimpanzees (Pan troglodytes) by Humans (Homo sapiens). Journal of Comparative Psychology. https://doi.org/10.1037/com0000327

2022. Eleuteri, V., Henderson, M., Soldati, A., Badihi, G., Zuberbühler, K., & Hobaiter, C. The form and function of chimpanzee buttress-drumming. Animal Behaviour. https://doi.org/10.1016/j.anbehav.2022.07.013

2022. Soldati, A., Muhumuza, G., Dezecache, G., Fedurek, P., Taylor, D., Call, J., & Zuberbühler, K. The Ontogeny of Vocal Sequences: Insights from a Newborn Wild Chimpanzee (Pan troglodytes schweinfurthii). International Journal of Primatology, 1-24. https://link.springer.com/article/10.1007/s10764-022-00321-y

2022. Soldati, A.*, Claire, B.*, Hobaiter, C., Stephen, M., De Moor, D., Zuberbühler, K.*, Dezecache, G.* Infrared thermal imaging as a window into primate social cognition: Insights from social feeding in wild chimpanzees. Philosophical Transactions of the Royal Society B. https://royalsocietypublishing.org/doi/10.1098/rstb.2021.0302

2022. Soldati, A., Fedurek, P., Crockford, C., Adue, S., Akankwasa, J. W., Asiimwe, C., Asua, J., Atayo, G., Chandia, B., Freymann, E., Fryns, C., Muhumuza G., Taylor, D., Zuberbühler, K., Hobaiter, C. Dead infant carrying by chimpanzee mothers in the Budongo Forest. Primates. https://link.springer.com/article/10.1007/s10329-022-00999-x

2022. Soldati, A., Fedurek, P., Dezecache, G., Call, J., Zuberbühler, K. Audience sensitivity in chimpanzee display pant hoots. Animal Behaviour. https://www.sciencedirect.com/science/article/pii/S0003347222001439?via%3Dihub

2022. Wilke, C.*, Lahiff, N. J.*, Badihi, G., Donnellan, E., Hobaiter, C., Machanda, Z., Mundry, R., Pika, S., Soldati, A., Wrangham, R., Zuberbühler, K., Slocombe, K.E. Referential gestures are not ubiquitous in wild chimpanzees: alternative functions for exaggerated loud scratch gestures. Animal Behaviour. https://www.sciencedirect.com/science/article/pii/S0003347222001014?via%3Dihub

2022. De Vevey, M., Bouchard A., Soldati, A., Zuberbühler, K. Thermal imaging reveals audience-dependent effects during cooperation and competition in wild chimpanzees. Scientific Reports. https://www.nature.com/articles/s41598-022-07003-y

2019. Kersken, V., Gómez, J. C., Liszkowski, U., Soldati, A., & Hobaiter, C. A gestural repertoire of 1-to 2-year-old human children: in search of the ape gestures. Animal Cognition. https://www.sciencedirect.com/science/article/pii/S0003347222001439?via%3Dihub

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