German Primate Center

The brain is thought to optimise behaviour by generating predictions based on learned statistical regularities. Predictive processing seemingly explains expectation suppression (ES), the attenuation of neural activity in response to expected stimuli. However, the mechanisms behind ES are unclear, with conflicting evidence for alternative models. Sharpening models propose that expectations suppress neurons away from the expected stimulus, increasing the signal-to-noise ratio and boosting decoding for expected stimuli. In contrast, dampening models posit that expectations suppress neurons that are tuned to the expected stimuli, reducing overall response magnitude and decoding accuracy. The opposing process theory (OPT) suggests that both processes occur at different time points, namely that initial sharpening is followed by later dampening of the neural representations of the expected stimulus. Here we test this theory and shed light on the dynamics of expectation effects, both at single-trial level and over time. Thirty-one participants completed a statistical learning task in which a 'leading' image from one category predicted a 'trailing' image from a different category. Multivariate EEG analyses decoded stimulus information related to the trailing category. Within-trial, expectation increased decoding accuracy at early latencies and decreased it at later latencies, in line with OPT. However, across trials, stimulus expectation decreased decoding accuracy in initial trials and increased it in later trials. We theorise that these dissociable dynamics of expectation effects within and across trials support hierarchical learning mechanisms. While within-trial results support the OPT, across-trial results suggest that sharpening and dampening effects emerge at distinct stages of associative learning.

Quantifying animal movements is necessary for answering a wide array of research questions in ecology and conservation biology. Consequently, ecologists have made considerable efforts to identify the best way to estimate an animal's home range, and many methods of estimating home ranges have arisen over the past half a century. Most of these methods fall into two distinct categories of estimators that have only recently been described in statistical detail: those that measure range distributions (methods such as kernel density estimation that quantify the long-run behavior of a movement process that features restricted space use) and those that measure occurrence distributions (methods such as Brownian bridge movement models and the Correlated Random Walk Library that quantify uncertainty in an animal movement path during a specific period of observation). In this paper, we use theory, simulations, and empirical analysis to demonstrate the importance of appropriately using these two categories of distributions and their estimators. Conflating range and occurrence distributions can have serious consequences for ecological inference and conservation practice. For example, in most situations, home ranges estimated using estimators of occurrence distributions are too small, and this problem is exacerbated by ongoing improvements in tracking technology that enable more frequent and more accurate data on animal movements. We encourage researchers to use estimators of range distributions to quantify home ranges and estimators of occurrence distributions to answer other questions in movement ecology, such as when and where an animal crossed a linear feature, visited a location of interest, or interacted with other animals.

The diet of wild non-human primates is still largely unknown, but advances in molecular techniques using DNA metabarcoding allow obtaining such information much faster and in more detail than until recently. The genus Trachypithecus is the most speciose and most broadly distributed genus among Asian colobines, a group of highly folivorous primates. The genus contains four species groups of which three occur in rainforest habitats while the fourth, the T. francoisi group, is restricted to limestone habitat. To characterize the food plant composition of langurs living in different habitats, we employed a metabarcoding approach and analyzed monthly samples (n = 419) collected over a 1-year period from T. crepusculus and T. germaini, members of the T. obscurus and T. cristatus groups, respectively, and T. delacouri and T. hatinhensis, both members of the T. francoisi group. By identifying plant taxa primarily to the genus level, we found that langur species consume a large number of different plants, with diets comprising of 122 - 129 plant genera across 59 - 73 families. While both overall dietary diversity and the most common plants consumed differed among the four species, we found no clear distinction between rainforest and limestone langurs. The four langur species also differed in their reaction to seasonal changes, as some species consumed different plants during dry and wet season, whereas others showed little change in plant consumption over the year. This study improves understanding of Trachypithecus dietary composition and represents the first dietary inventory of T. crepusculus in Vietnam.

ABSTRACT Research characterises the child as an active learner who attends more to and selectively retains information they actively elicit better than information they passively receive. At the same time, children learn best from knowledgeable others who tailor information to children's learning progress. Bringing these disparate findings together requires examining children's active learning in social interactions. The current study examines whether the active learning advantage persists in social interactions with others and is influenced by the pedagogical status of their social partner (mother, father or friend). We tested 4‐ to 5‐year‐old children with their social partners ( N friend = 47, N mother = 44, N father = 53) during a word learning task using a novel setup where two participants can interact with visual objects on a transparent touchscreen while observing each other. Participants could either actively choose objects to hear their labels or passively observe their partner's choices. Early in the task, there was an overall active benefit, although this pattern appeared to be predominantly driven by interactions between peers. Later in the task, learning appeared to be dynamic and more influenced by the social partner with whom the child was interacting, especially when considering interactions with their peers and their fathers. Together, these findings underscore the temporal and social dynamics of an active learning benefit in children's social interactions.

Human-wildlife conflicts arise from increasing human populations and the growing demand for land for agriculture and urban development. In Saudi Arabia, these dynamics have increased the impact of baboons on human communities, as expanding settlements encroach upon the natural habitats of baboons, while rising baboon populations increasingly invade urban areas in search of food, shelter, and water. We aimed to assess the effects of human-baboon coexistence on residents in the Al-Baha region, Saudi Arabia. From October 2021 to April 2022, we administered a 43-item semi-structured online questionnaire addressing emotional, social, environmental and financial impacts of nearby baboons. A total of 318 residents of the Al-Baha region completed the survey and shared their experiences regarding interactions with hamadryas baboons (Papio hamadryas) near human properties. In addition, three semi-structured life interviews with residents aged over 70 explored historical perceptions. Respondents attributed increased baboon presence to urban expansion, accessible waste, and intentional feeding and strongly supported government-led mitigation plans. Human-baboon interactions in Al Baha produce emotional stress, social disruption, and economic burdens for residents. Findings support integrated management combining public education, improved waste management, non-lethal deterrents, and carefully planned population control measures, developed with community consultation. Limitations of the study include convenience online sampling and reliance on self-reported impacts; future work should quantify baboon abundance and objectively measure economic losses.

Social interactions in human and non-human primates are actively investigated in psychology, primatology, cognitive science, and neuroscience. Experimental investigations of such interactions could benefit from using human- or primate-like artificial

Abstract The common marmosets (Callithrix jacchus) are valuable non-human primate (NHP) animal models in biomedical research, including infectious diseases modelling. However, for in vitro studies only few immortalized cell lines have been generated, and additional lines are needed and will help to comply with the 3R principles or replacement, reduction and refinement. Here, we present the generation and characterization of three cell lines derived from kidney tissue, which were immortalized by transduction of SV40 large T antigen. The cell lines display an epithelioid morphology, show differential podoplanin expression and are likely of pericyte origin, as deduced from expression profiles of marker genes obtained by RNA sequencing analysis (RNA-seq). All cell lines had a functional interferon system, as shown by responsiveness to human IFNβ and marmoset IFNα14 and the induction of interferon-stimulated genes. Infection with retroviral pseudotypes demonstrated susceptibility to entry driven by glycoproteins from a wide range of human pathogenic viruses. Finally, these cell lines are highly permissive for Zika virus, for which marmosets are a model organism, and Herpes simplex virus 1, which causes a deadly disease in marmosets. We believe that these cell lines are a valuable resource for in vitro studies on marmosets.