2. Izbor iz vojne ostavine Svetozara Borojevića od Bojne; 2.1.7. Razdoblje između Četvrte i Šeste bitke na Soči (sredina prosinca 1915. do početka kolovoza 1916.)

Ecological immunology proposes that the optimal immune defence, and the costs coming with it, vary across environments. In environments with higher pathogen load, the immune system should experience greater challenges and, therefore, investment in maintaining it should be higher. The biomarker neopterin allows monitoring of innate immune responses, and is therefore an ideal tool to investigate the effects of ecological variables on the immune system. Here, we compared urinary neopterin levels of apparently healthy chimpanzees without acute symptoms of sickness across two environments: in captivity (22 zoos) and in the wild (two populations)

Group-specific expressions of co-feeding tolerance in bonobos and chimpanzees preclude dichotomous species generalizations

Bonobos are typically portrayed as more socially tolerant than chimpanzees, yet the current evidence supporting such a species-level categorization is equivocal. Here, we used validated group-level co-feeding assays to systematically test expressions of social tolerance in sixteen groups of zoo- and sanctuary-housed bonobos and chimpanzees. We found that co-feeding tolerance substantially overlaps between the species, thus precluding categorical inference at the species level. Instead, marked differences were observed between groups, with some bonobo communities exhibiting higher social tolerance than chimpanzee communities, and vice versa. Moreover, considerable intergroup variation was found within species living in the same environment, which attests to Pan's behavioral flexibility. Lastly, chimpanzees showed more tolerance in male-skewed communities, whereas bonobos responded less pronounced to sex-ratio variation. We conclude that the pervasive dichotomy between the tolerant bonobo and the belligerent chimpanzee requires quantitative nuance, and that accurate phylogenetic tracing of (human) social behavior warrants estimations of intraspecific group variation

Group-level variation in co-feeding tolerance between two sanctuary-housed communities of chimpanzees (Pan troglodytes)

Social tolerance in group-living animals can be viewed as a counterweight against competitive interests necessary to obtain coexistence equilibrium and maintain group cohesion. As such, it forms an interesting phenomenon to study at the group level, but how can this be done most informatively? Here, we use three group-level co-feeding assays and social network analysis to study social tolerance in two groups of chimpanzees living under similar circumstances within a sanctuary to i) reassess whether social tolerance may be a group-specific parameter in chimpanzees and derive inferences about its long-term stability, and ii) compare the characteristics and resultant patterns between two established and one new assay. We show that the three assays expose the same (predicted) group-level differences in social tolerance as in the previous study eight years ago, thereby providing preliminary evidence for stability in group-specific levels of social tolerance in chimpanzees, despite changing group compositions. Furthermore, from an experimental point of view, we identify the new assay as more valid than the two established ones based on the consideration that resources may deplete at different rates across groups, which would consequently alter the need for tolerance differentially. We discuss implications for the study of social tolerance and highlight the importance of taking into account intraspecific variation in social animals

Social culture in bonobos

Van Leeuwen et al. found that two peculiar interactive behaviors (social scratching and groom slapping) transmitted socially through bonobo networks across six European zoos

Social culture in bonobos

Van Leeuwen et al. found that two peculiar interactive behaviors (social scratching and groom slapping) transmitted socially through bonobo networks across six European zoos

Bonobos and chimpanzees preferentially attend to familiar members of the dominant sex

Social animals must carefully track consequential events and opportunities for social learning. However, the competing demands of the social world produce trade-offs in social attention, defined as directed visual attention towards conspecifics. A key question is how socioecology shapes these biases in social attention over evolution and development. Chimpanzees, Pan troglodytes, and bonobos, Pan paniscus, provide ideal models for addressing this question because they have large communities with fission–fusion grouping, divergent sex-based dominance hierarchies and occasional intergroup encounters. Using noninvasive eye-tracking measures, we recorded captive apes’ attention to side-by-side images of familiar and unfamiliar conspecifics of the same sex. We tested four competing hypotheses about the influence of taxonomically widespread socioecological pressures on social attention, including intergroup conflict, dominance, dispersal and mating competition. Both species preferentially attended to familiar over unfamiliar conspecifics when viewing the sex that typically occupies the highest ranks in the group: females for bonobos, and males for chimpanzees. However, they did not demonstrate attentional biases between familiar and unfamiliar members of the subordinate sex. Findings were consistent across species despite differences in which sex tends to be more dominant. These results suggest that sex-based dominance patterns guide social attention across Pan. Our findings reveal how socioecological pressures shape social attention in apes and likely contribute to the evolution of social cognition across primates

Bonobos and chimpanzees preferentially attend to familiar members of the dominant sex

Social animals must carefully track consequential events and opportunities for social learning. However, the competing demands of the social world produce trade-offs in social attention, defined as directed visual attention towards conspecifics. A key question is how socioecology shapes these biases in social attention over evolution and development. Chimpanzees, Pan troglodytes, and bonobos, Pan paniscus, provide ideal models for addressing this question because they have large communities with fission–fusion grouping, divergent sex-based dominance hierarchies and occasional intergroup encounters. Using noninvasive eye-tracking measures, we recorded captive apes’ attention to side-by-side images of familiar and unfamiliar conspecifics of the same sex. We tested four competing hypotheses about the influence of taxonomically widespread socioecological pressures on social attention, including intergroup conflict, dominance, dispersal and mating competition. Both species preferentially attended to familiar over unfamiliar conspecifics when viewing the sex that typically occupies the highest ranks in the group: females for bonobos, and males for chimpanzees. However, they did not demonstrate attentional biases between familiar and unfamiliar members of the subordinate sex. Findings were consistent across species despite differences in which sex tends to be more dominant. These results suggest that sex-based dominance patterns guide social attention across Pan. Our findings reveal how socioecological pressures shape social attention in apes and likely contribute to the evolution of social cognition across primates

Erratum to “Bonobos and chimpanzees preferentially attend to familiar members of the dominant sex” [Animal Behaviour 177 (2021) 193–206] (Animal Behaviour (2021) 177 (193–206), (S000334722100138X), (10.1016/j.anbehav.2021.04.027))

It was discovered that the original online version of the above article contained errors that were not the fault of the authors. The affiliations of two authors, Fumihiro Kano and Christopher Krupenye, were listed incorrectly on the title page of the article. The Publisher decided to ‘resupply’ (repost and replace) the XML and online PDF of the article. The printed issue has also been correspondingly altered. Elsevier regrets and apologizes for any inconvenience caused by posting (and printing) a new version of this article online, but hopes that the reader will understand the reasons for doing so.</p