Biology subjects

Zuberbuehler, K.

Publications and source records attributed to Zuberbuehler, K..

5 recordsLinked to original sources

bioRxiv2025

Rule-based sequences in sooty mangabey vocal communication

Investigating how non-human animals produce call sequences provides key insights into the evolutionary origins of meaning in vocal communication, including syntax. Many species combine calls into structured sequences, often following specific rules, yet most studies focus on only a few sequences per species. This limits our understanding of their ability to combine calls and convey meaning through sequences. Our study addresses this gap by documenting the vocal sequence repertoire and underlying rules of sooty mangabeys (Cercocebus atys), a West African monkey species. We collected and analysed 1,672 recordings from two wild groups in the Tai National Park, Ivory Coast. Sooty mangabeys frequently combine calls but rely on a limited set of sequences. Within these, we identified rules of call ordering, recurrence and hierarchical structuring. Notably, they produced hierarchically structured sequences using only two call types, a previously unreported system in animal communication. Our findings suggest that sooty mangabeys use both structured and unstructured sequences, likely encoding different types of information. While context of production remains essential for determining meaning, our results highlight how a whole-repertoire approach reveals the full range of rule-based sequences and their potential for meaning expansion beyond the number of individual calls available in the repertoire.

animal behavior and cognition↗

bioRxiv2025

Toxoplasma in a natural population of chimpanzees

Toxoplasma gondii is a unicellular parasite that can infect most warm-blooded animals. In humans, it is linked to schizophrenia and other neurological disorders. It is also responsible for congenital toxoplasmosis, which can be lethal or cause severe neurological damage in the developing foetus. More subtle behavioural effects have been observed in various species, including humans, in particular increased risk-taking, which is thought to increase the parasites transmission to feline predators, the definitive hosts. We investigated the prevalence of Toxoplasma gondii in wild eastern chimpanzees (Pan troglodytes schweinfurthii) in the Budongo Forest, Uganda. We tested 45 individuals of two communities, one of which (Sonso) has a home range overlapping with human settlements. In this community, the prevalence was 22.7% (N=5 of 22), whereas in the neighbouring, but more isolated, Waibira community none of the 23 individuals tested were infected. The majority of infected Sonso individuals were adult males and/or high-ranking group members, attributes associated with increased risk-taking behaviour in chimpanzees and other animals. While further work is necessary to reveal the causal relation between infection and behaviour, our findings open new avenues of research for the neural impact of parasites on primate social behaviour.

zoology↗

bioRxiv2023

Primate origins of human event cognition

Human language relies on a rich cognitive machinery, partially shared with other animals. One key mechanism, decomposing events into causally-linked agent-patient roles, however, has remained elusive with no known animal equivalent. In humans, agent-patient relations in event cognition drive how languages are processed neurally and expressions structured syntactically. We compared visual event tracking between humans and great apes, using stimuli that would elicit causal processing in humans. After accounting for attention to background information, we found similar gaze patterns to agent-patient relations in all species, mostly alternating attention to agents and patients, presumably in order to learn the nature of the event, and occasionally privileging agents under specific conditions. Six-month-old infants, in contrast, did not follow agent-patient relations and attended mostly to background information. We conclude that event role tracking, a cognitive foundation of syntax, evolved long before language but requires time and experience to become ontogenetically available. Significance statementHuman adults and great apes, but not human infants, track natural events as agent-patient relations, a cognitive foundation for syntax.

animal behavior and cognition↗

bioRxiv2021

Non-genetic maternal effects shape individual differences in cortisol phenotypes in wild chimpanzees

Glucocorticoids, such as cortisol, mediate homeostatic processes, allowing individuals to adjust to fluctuating environments. The regulation of circadian cortisol responses, a key homeostatic function, has been shown to be heritable. However, to understand better the role of parental care in shaping physiological functioning in long-lived mammals with protracted parental care, there is a need to disentangle genetic and non-genetic parental contributions to variation in glucocorticoid phenotypes. We used a dataset of 6,123 cortisol measures from urine samples from 170 wild chimpanzees spanning 18 years of data collection. We found consistent inter-individual differences in circadian cortisol phenotypes, with differences most apparent when considering average cortisol levels given the effect of time of day. Maternal effects explained around 10% (2-18%) variation in these average cortisol levels, while variation attributable to genetic factors was not distinguishable from zero. Our results indicate, relative to genetic effects, a qualitatively stronger influence of mothers, whether via epigenetic processes or via behavioral priming for coping with stressors, in shaping cortisol phenotypes in this species. This provides novel insight into the vital role of mothers in the developmental plasticity of long-lived mammals and, more generally, the selective pressures shaping physiological plasticity.

zoology↗

bioRxiv2019

An information-theory approach to geometry for animal groups

One of the hardest problems in studying animal behaviour is to quantify patterns of social interaction at the group level. Recent technological developments in global positioning system (GPS) devices have opened up new avenues for locating animals with unprecedented spatial and temporal resolution. Likewise, advances in computing power have enabled new levels of data analyses with complex mathematical models to address unresolved problems in animal behaviour, such as the nature of group geometry and the impact of group-level interactions on individuals. Here, we present an information theory-based tool for the analysis of group behaviour. We illustrate its affordances with GPS data collected from a freely interacting pack of 15 Siberian huskies (Canis lupus familiaris). We found that individual freedom in movement decisions was limited to about 4%, while a subjects location could be predicted with 96% median accuracy by the locations of other group members, a pattern mediated by dominance, kin relations, sex, the relative time of the day and external events, such as feeding. We conclude that information theory-based approaches, coupled with state-of-the-art bio-logging technology, provide a powerful tool for future studies of animal social interactions beyond the dyadic level.

animal behavior and cognition↗