Trade-offs in the production of animal vocal sequences:insights from the structure of wild chimpanzee pant hoots

The study was funded by Swiss National Science Foundation (310030_143359) and European Research Council project grants awarded to KZ (PRILANG 283871).Background Vocal sequences - utterances consisting of calls produced in close succession - are common phenomena in animal communication. While many studies have explored the adaptive benefits of producing such sequences, very little is known about how the costs and constraints involved in their production affect their form. Here, we investigated this issue in the chimpanzee (Pan troglodytes schweinfurthii) pant hoot, a long and structurally complex vocal sequence comprising four acoustically distinct phases – introduction, build-up, climax and let-down. Results We found that in each of these phases, and for the sequence as a whole, there was a negative relationship between the number of calls produced and their average duration. There was also a negative relationship between the total duration of some adjacent phases. Significant relationships between the fundamental frequency of calls and their number or duration were found for some phases of the sequence, but the direction of these relationships differed between particular phases. Conclusions These results indicate that there are trade-offs in terms of signal duration at two levels in pant-hoot production: between call number and duration, and between the relative durations of successive phases. These trade-offs are likely to reflect biomechanical constraints on vocal sequence production. Phase-specific trade-offs also appear to occur between fundamental frequency and call number or duration, potentially reflecting that different phases of the sequence are associated with distinct types of information, linked in different ways to call pitch. Overall, this study highlights the important role of costs and constraints in shaping the temporal and acoustic structure of animal vocal sequences.Publisher PDFPeer reviewe

Sequential information in a great ape utterance

Birdsong is a prime example of acoustically sophisticated vocal behaviour, but its complexity has evolved mainly through sexual selection to attract mates and repel sexual rivals. In contrast, non-human primate calls often mediate complex social interactions, but are generally regarded as acoustically simple. Here, we examine arguably the most complex call in great ape vocal communication, the chimpanzee (Pan troglodytes schweinfurthii) â € pant hoot'. This signal consists of four acoustically distinct phases: introduction, build-up, climax and let-down. We applied state-of-The-Art Support Vector Machines (SVM) methodology to pant hoots produced by wild male chimpanzees of Budongo Forest, Uganda. We found that caller identity was apparent in all four phases, but most strongly in the low-Amplitude introduction and high-Amplitude climax phases. Age was mainly correlated with the low-Amplitude introduction and build-up phases, dominance rank (i.e. social status) with the high-Amplitude climax phase, and context (reflecting activity of the caller) with the low-Amplitude let-down phase. We conclude that the complex acoustic structure of chimpanzee pant hoots is linked to a range of socially relevant information in the different phases of the call, reflecting the complex nature of chimpanzee social lives

The relationship between food calling and agonistic behaviour in wild chimpanzees

A number of social animals produce food-associated calls, which have been interpreted as informative and referential about the quality or quantity of food accessed by the caller. In chimpanzees, however, some behavioural patterns have remained unexplained by this model, suggesting that food-associated calls have a more generalized social function beyond attracting others to food, such as promoting tolerance between co-feeding individuals. In this study, we investigated how wild chimpanzees (Pan troglodytes schweinfurthii) of Budongo Forest, Uganda, use food associated-calls in situations when social tolerance is low, i.e., during agonistic interactions. We found a positive relationship between food calling and agonistic behaviours during a feeding event, independent of the number of males on the feeding patch. Moreover, food calling followed rather than preceded agonistic interactions, suggesting that aggression can trigger food call production. These results support the view that chimpanzee food-associated calls can act as social tools mediating competitive or aggressive interactions

Social and ecological correlates of long-distance pant hoot calls in male chimpanzees

Long-distance calls have a variety of functions in different animal species. However, where multiple functions are proposed for a single long-distance call type, little is known about their relative importance. Chimpanzees are one species where several functions have been proposed for their long-distance call, the pant hoot. In this study, we investigated the effect of social factors, including the rank of the caller, party size, fission-fusion rates, and the presence of estrus females as well as ecological factors including the type of food consumed and travel time, on male chimpanzee (Pan troglodytes schweinfurthii) pant hooting, in order to identify the key correlates of this behavior. The wild male chimpanzees of the Kanyawara community, Uganda, produced more pant hoots on days when there were frequent changes in the male, but not female, composition of the focal's party. This factor accounted for the largest amount of variation in pant hoot production, and we found that males were more likely to repeat a call prior to rather than after fusion with other males, suggesting that the calls facilitate fusion. Pant hoots therefore seem to play a pivotal role in regulating grouping dynamics in chimpanzees. Our study also shows that pant hooting was positively correlated with the rank of the caller, the presence of parous females in estrus, and the consumption of high-quality food, suggesting that pant hoots signal social status or social bonds when between-male competition is high. This study supports the view that pant hoots fulfill a complex social function

Audience sensitivity in chimpanzee display pant hoots

Audience effects are key in studies of animal social cognition and are typically investigated during directed social interactions. Male chimpanzees, Pan troglodytes, regularly perform aggressive displays in the presence of others, often targeting a specific group member, and combine this agonistic behaviour with acoustic signals. Here, we were interested in whether the production and structure of pant hoots, a long-distance signal, were influenced by audience composition (i.e. presence and absence of specific individuals). We investigated pant hoots produced during displays by adult and subadult males of Budongo Forest, Uganda. We found that males overall called more often when their preferred social partners and females were absent from the party, as well as when more dominant males were present. We then separately analysed the four phases of pant hoots, introduction, build-up, climax and let-down, and found that audience composition and social context could often explain the presence or absence of each phase. In addition, displays were often accompanied by drumming, especially by older males and when male audiences were small. Our study adds to the growing body of literature on audience effects and other social factors and shows their impact on the structure of a sophisticated vocal sequence, which enhances the communicative capacity in a species with limited vocal control

Men With a Terminal Illness Relax Their Criteria for Facial Attractiveness

According to the life history paradigm, in life-threatening conditions, sexual selection criteria are relaxed in order to increase the probability of a last resort reproduction, ultimately contributing to reproductive success. This should be reflected in loosened mating preferences — a process observed in nonhuman animals. Studies investigating this aspect in humans, however, are scarce. This study explored the aesthetic preferences towards facial and nonfacial stimuli in terminally ill patients with heart failure (HF) and their healthy, same-sex peers. The aim was to examine if these two groups of men demonstrate different patterns of aesthetic judgments. Using a 7-point scale, 65 male patients with HF and 143 healthy men evaluated the perceived attractiveness of 15 photographs (five adult male faces, five adult female faces, and five nonfacial pictures). A mixed-design analysis of variance was run to assess group differences in aesthetic preferences. Compared to healthy controls, stimuli. HF patients rated the pictures using significantly higher scores, but this applied only to male and female, but not nonfacial, stimuli. We propose that lower criteria for facial attractiveness in HF patients are linked to relaxation of mate preferences as a result of a life-threatening conditions, and that this process can be an adaptive mating strategy from an ultimate, evolutionary perspective. However, other mechanisms (e.g., seeking social support) may be also responsible for the observed patterns

The effect of warning signs on the presence of snare traps in a Ugandan rainforest

BCFS receives core funding from the Royal Zoological Society of Scotland. The Budongo Snare Removal Project is funded by Oakland Zoo. PF was funded by the European Research Council project grant to CC (grant agreement number: 679787). DPD was funded by the National Science Centre (grant number: 2020/04/X/NZ8/00865).Since chimpanzee (Pan troglodytes) conservation often involves local human populations, conservation strategies must consider psychological factors that impact their behavior. In Budongo Forest, Uganda, for example, local communities commonly engage in snare trap (hereafter: snare) setting for wild meat. This illegal activity posits a substantial threat to wild chimpanzees, causing permanent wounds or death for those who are snared. Despite various schemes previously implemented to address snare setting?an activity that is fueled by poverty, the problem and its detrimental impact on chimpanzees persists. Here, we experimentally tested a novel intervention, a systematic display of specially designed warning signs aimed at local poachers. We monitored the presence of snares before and after introducing these signs over a total period of two years and compared it with that of a similar sized control area with no intervention. Results show that snares were less likely to be present during the ?sign? period than during the ?non-sign? period in the experimental but not in the control area. We discuss the potential of this cost-effective intervention for limiting illegal activities that pose a severe threat to chimpanzees and other species inhabiting tropical forests.Publisher PDFPeer reviewe

Like Father, Like Child? Paternal Age at Birth and Offspring's Facial Asymmetry and Distinctiveness

Paternal age at birth, a potential proxy of mutation load transmitted to the offspring, has previously been related to the offspring’s health, biological condition and reproductive potential. As higher facial asymmetry and distinctiveness serve as putative markers of the lower genetic quality of an individual, we hypothesize that more advanced paternal age at birth will be related to children’s higher levels of facial asymmetry and distinctiveness. To the best of our knowledge, this is the first study evaluating the link between paternal age at birth and facial asymmetry in offspring. Based on archived photographs of 159 children born within 47 Polish families, we have conducted facial geometric morphometric measurements and calculated the levels of facial asymmetry and distinctiveness. The relationship between paternal age at birth and the offspring’s facial features was explored with the use of Bayesian Linear Mixed-effects Models, controlling for sex, age and birth order of the offspring, and maternal age at child’s birth. No associations between paternal age at birth and facial asymmetry or distinctiveness in children were found. The lack of such a relationship might be a result of the potentially insufficient influence of newly accumulated paternal mutations affecting the offspring’s phenotype or higher importance of maternal (prenatal) and postnatal environments in shaping facial features

First observation of a chimpanzee with albinism in the wild : social interactions and subsequent infanticide

Maël Leroux was funded via the Swiss National Science Foundation grant awarded to Simon W. Townsend (31003A_153065). Pawel Fedurek was funded via the European Research Council project grant awarded to Catherine Crockford (grant agreement number: 679787).Albinism- the congenital absence of pigmentation- is a very rare phenomenon in animals due to the significant costs to fitness of this condition. Both humans and non-human individuals with albinism face a number of challenges, such as reduced vision, increased exposure to ultraviolet radiation, or compromised crypticity resulting in an elevated vulnerability to predation. However, while observations of social interactions involving individuals with albinism have been observed in wild non-primate animals, such interactions have not been described in detail in non-human primates (hereafter, primates). Here, we report, to our knowledge, the first sighting of an infant with albinism in wild chimpanzees (Pan troglodytes schweinfurthii), including social interactions between the infant, its mother, and group members. We also describe the subsequent killing of the infant by conspecifics as well as their behavior towards the corpse following the infanticide. Finally, we discuss our observations in relation to our understanding of chimpanzee behavior or attitudes towards individuals with very conspicuous appearances.Publisher PDFPeer reviewe

A Reconsideration of Proofs for God’s Existence in the Philosophy of Kvirin Vasilj

U članku se istražuje kritika tradicionalnih dokaza Božjega postojanja u filozofa Kvirina Vasilja (1917.–2006.). Autor članka ne izlaže niti obrazlaže tradicionalne dokaze, o tome postoji opsežna literatura koja je dijelom natuknuta u bilješkama. U prvome dijelu članka iznosi se Vasiljeva kritika apriornih dokaza Božjega postojanja, u drugome aposteriornih, a u trećem antropoloških. Iako redom odbija sve dokaze Božjega postojanja, Vasilj ne daje za pravo ni onima koji smatraju da su pobijajući dokaze Božjega postojanja osporili svaku mogućnost istinitoga dokaza, o čemu se govori u četvrtome dijelu. U petome dijelu autor izlaže Vasiljeve vlastite dokaze Božjega postojanja: »iz postanka živih bića uopće« i »iz postanka svake ljudske osobe«.The paper examines critiques of traditional proofs for the existence of God in the works of philosopher Kvirin Vasilj (1917–2006). The author neither puts forward nor clarifies traditional proofs — extensive writings on these already exist, some of which are cited in the footnotes. The first section of the paper expounds Vasilj’s critique of a priori proofs of God’s existence; the second, a posteriori and the third, anthropological proofs. Though he systematically rejects all proofs for the existence of God, Vasilj does not vindicate those who consider that, in refuting proofs of God’s existence, they have contested each and every possibility of finding a veritable proof, which is the theme of the fourth section. The fifth section deals with Vasilj’s proper proofs for God’s existence »from the origin of all living things« and »from the origin of every human person«