Contagious yawning in African painted dogs.

Contagious yawning (CY), which is yawning elicited by sensing another yawning, has been observed only in social species and is considered linked to high sociality. Although this idea-the social communication hypothesis-is supported by previous studies, investigating the occurrence of CY in various species remains necessary. We investigated the occurrence of CY in one of the most social canine species, the African painted dog (Lycaon pictus). We recorded 1387 yawn events from five pairs (10 individuals) in captivity. Temporal analysis showed that subsequent yawns occurred frequently within 15 s or 30 s after spontaneous yawns (SYs). SYs that were detectable by another individual (i.e., visible to the other individual or performed in close proximity) were more likely to elicit subsequent yawns by the other individual. However, the influence of contextual factors on CY differed according to the time window, implying that a conservative time window should be used to reduce overcounting of CY and misattribution of its determinants. The proportion of CY was positively related to time spent in physical proximity to another, a proxy for a social bond. Overall, our results provide the first evidence of CY in African painted dogs and further support the notion that such behavior is prevalent among social animals. They also strongly imply that an appropriate time window should be used to define yawn contagion.

Exploring the incidence and etiopathogenesis of pathological yawning as adverse side effect of psychotropic drugs.

INTRODUCTION: Yawning is a normal, stereotyped physiological event in humans and animal kingdom. When excessive (>3 per 15 minutes), it is termed as pathological yawning (PY). PY could be due to many causes but more commonly associated with side-effect of drugs, notably involving those used in psychopharmacology. Though there are isolated case reports and case-series, there are no large-scale reports of PY. This work attempted to address this lacuna. MATERIAL AND METHODS: The current work attempted to identify characteristics of PY as collated from adverse drug effect databases of Australia (Database of Adverse Event Notifications), Canada (Canada Vigilance Adverse Reaction Online Database) and the United States of America (FDA Adverse Event Reporting System - FAERS). These databases collect and provide public access to reports of adverse events related to drugs and therapeutic goods. They act as a prime pharmacovigilance tool as well as a first-line resource for healthcare professionals, researchers, and the public to monitor the safety of these products and make informed decisions. In the first week of June 2023, open access, unrestricted adverse effect of drug databases were explored, using the word "YAWNING" as the only search term for the side effect of any drug without any restrictions. The collected details of PY cases with their gender, age, reason for drug use, other concomitant complaints as well as the nature of adverse event(s) and its treatment requirements were assessed. Descriptive statistics were used. RESULT: Of the 2655 instances in USA database, 398(15%) had more than 1 suspect drug and in total 578 medications involved. The most commonly involved drugs were apomorphine, sertraline, fluoxetine and paroxetine. In all 341(12.8%) cases reported of YAWN alone or with one another sleep disorder, the most common off ending drug were fluoxetine hydrochloride. DISCUSSION AND CONCLUSION: The neural mechanism and physiology of yawning are explained. This study stresses that a health care professional, particularly mental health professionals and neurologists, should be aware of the importance of PY to deliver the best for the patients under their care. (Neuropsychopharmacol Hung 2023; 25(4): 194-205)

Yawning and airway physiology: a scoping review and novel hypothesis.

BACKGROUND AND PURPOSE: Yawning is a stereotypical complex muscular movement and is commonly executed by most vertebrates. In seconds, the entire airway is fully dilated and surrounding muscles are powerfully stretched, most prominently around the pharynx. To date, yawning has been rarely studied, and as of yet there is no consensus on its main function. MATERIAL AND METHODS: To investigate a mechanical airway function for yawning, a literature search was conducted to relate the frequency of yawning and obstructive airway conditions. RESULTS: The results show that changes in obstructive airway conditions and alteration of the frequency of yawning are temporally related. INTERPRETATION: These relationships, however, cannot be interpreted as causal, nor can they be extrapolated to explain the function of yawning. Yet airway management and yawning share many physiological characteristics. We therefore propose a novel hypotheses: yawning plays a significant role in airway physiology by muscle repositioning and widening the airway lumen, thereby securing long-term oxygenation.

Yawn contagion in bonobos: Another group, another story.

In primates, yawn contagion (the yawning response elicited by others' yawn) is variably influenced by individual (e.g., sex, age) and social factors (e.g., familiarity) and possibly linked to interindividual synchronization, coordination, and emotional contagion. Two out of three studies on yawn contagion in bonobos (Pan paniscus), found the presence of the phenomenon with mixed results concerning the effect of familiarity and no replication on its modulating factors. To address this puzzling issue, we recorded all occurrences data on yawn contagion in a captive bonobo group (March-June 2021; 18 individuals; La Vallée des Singes, France). Contrary to chimpanzees and humans, the number of triggering yawns increased contagion, possibly owing to a higher stimulus threshold. This aspect may explain the interindividual variability observed in yawn contagion rates. In subjects under weaning, we did not detect yawn contagion and, as it occurs in certain human cohorts, yawn contagion declined with age, possibly due to reduced sensitivity to others. Females responded more than males and elicited more responses from females when showing sexual swelling. As reproductive females are central in bonobo society, our results support the hypothesis that-as in other Hominini-the most influential sex can influence yawn contagion. The relationship quality (measured via grooming/play) did not affect yawn contagion, possibly due to bonobos' xenophilic nature. Overall, this study confirms the presence of yawn contagion in bonobos and introduces new elements on its modulating factors, pointing toward the necessity of cross-group studies.

Factors influencing alertness to premonitory symptoms in stroke patients with pre-hospital delay.

OBJECTIVE: The purpose was to explore the alertness of premonitory symptoms in stroke patients with prehospital delay, and to analyze the influencing factors. DESIGN AND SAMPLE: A cross-sectional study using the convenience sampling method was conducted in the neurology department of a general hospital between November 2018 and July 2019. A total of 352 stroke patients were participated in the survey. MEASURES: A hierarchical multiple regression was performed to analyze the factors related to the alertness of premonitory symptoms (0-9 scores) in stroke patients with prehospital delay. RESULTS: The alertness score was 6.53 ± 2.377. The lowest score of 0.55 ± 0.498 was for "Continuous yawning occurs continuously despite no tiredness or lack of sleep is okay, and need not be treated." The hierarchical regression results revealed that symptom onset, symptom change before admission, knowledge, social support were the influencing factors delaying the alertness of premonitory symptoms. Knowledge and support from friends could improve the alertness, while support from family and other support had a notable negative impact. CONCLUSIONS: Stroke patients need to be more alert toward premonitory symptoms. This alertness is related to stroke knowledge and social support. Nurses should formulate interventions and advise stroke patients to improve their stroke knowledge and expand their social network.

The premonitory phase of migraine is due to hypothalamic dysfunction: revisiting the evidence.

OBJECTIVE: To critically appraise the evidence for and against premonitory symptoms in migraine being due to hypothalamic dysfunction. DISCUSSION: Some premonitory symptoms (e.g. fatigue, mood changes, yawning, and food craving) are associated with the physiologic effects of neurotransmitters such as orexins, neuropeptide Y, and dopamine; all of which are expressed in hypothalamic neurons. In rodents, electrophysiologic recordings have shown that these neurotransmitters modulate nociceptive transmission at the level of second-order neurons in the trigeminocervical complex (TCC). Additional insights have been gained from neuroimaging studies that report hypothalamic activation during the premonitory phase of migraine. However, the available evidence is limited by methodologic issues, inconsistent reporting, and a lack of adherence to ICHD definitions of premonitory symptoms (or prodromes) in human experimental studies. CONCLUSIONS: The current trend to accept that premonitory symptoms are due to hypothalamic dysfunction might be premature. More rigorously designed studies are needed to ascertain whether the neurobiologic basis of premonitory symptoms is due to hypothalamic dysfunction or rather reflects modulatory input to the trigeminovascular system from several cortical and subcortical areas. On a final note, the available epidemiologic data raises questions as to whether the existence of premonitory symptoms and even more so a distinct premonitory phase is a true migraine phenomenon. Video recording of the debate held at the 1st International Conference on Advances in Migraine Sciences (ICAMS 2022, Copenhagen, Denmark) is available at: https://www.youtube.com/watch?v=d4Y2x0Hr4Q8 .

Differential Contribution of the Retrotrapezoid Nucleus and C1 Neurons to Active Expiration and Arousal in Rats.

Collectively, the retrotrapezoid nucleus (RTN) and adjacent C1 neurons regulate breathing, circulation and the state of vigilance, but previous methods to manipulate the activity of these neurons have been insufficiently selective to parse out their relative roles. We hypothesize that RTN and C1 neurons regulate distinct aspects of breathing (e.g., frequency, amplitude, active expiration, sighing) and differ in their ability to produce arousal from sleep. Here we use optogenetics and a combination of viral vectors in adult male and female Th-Cre rats to transduce selectively RTN (Phox2b+/Nmb+) or C1 neurons (Phox2b+/Th+) with Channelrhodopsin-2. RTN photostimulation modestly increased the probability of arousal. RTN stimulation robustly increased breathing frequency and amplitude; it also triggered strong active expiration but not sighs. Consistent with these responses, RTN innervates the entire pontomedullary respiratory network, including expiratory premotor neurons in the caudal ventral respiratory group, but RTN has very limited projections to brainstem regions that regulate arousal (locus ceruleus, CGRP+ parabrachial neurons). C1 neuron stimulation produced robust arousals and similar increases in breathing frequency and amplitude compared with RTN stimulation, but sighs were elicited and active expiration was absent. Unlike RTN, C1 neurons innervate the locus ceruleus, CGRP+ processes within the parabrachial complex, and lack projections to caudal ventral respiratory group. In sum, stimulating C1 or RTN activates breathing robustly, but only RTN neuron stimulation produces active expiration, consistent with their role as central respiratory chemoreceptors. Conversely, C1 stimulation strongly stimulates ascending arousal systems and sighs, consistent with their postulated role in acute stress responses.SIGNIFICANCE STATEMENT The C1 neurons and the retrotrapezoid nucleus (RTN) reside in the rostral ventrolateral medulla. Both regulate breathing and the cardiovascular system but in ways that are unclear because of technical limitations (anesthesia, nonselective neuronal actuators). Using optogenetics in unanesthetized rats, we found that selective stimulation of either RTN or C1 neurons activates breathing. However, only RTN triggers active expiration, presumably because RTN, unlike C1, has direct excitatory projections to abdominal premotor neurons. The arousal potential of the C1 neurons is far greater than that of the RTN, however, consistent with C1's projections to brainstem wake-promoting structures. In short, C1 neurons orchestrate cardiorespiratory and arousal responses to somatic stresses, whereas RTN selectively controls lung ventilation and arterial Pco2 stability.

Premonitory symptoms in migraine from China: A multi-clinic study of 4821 patients.

OBJECTIVE: To observe the prevalence and characteristics of premonitory symptoms in Chinese migraineurs and explore their associations with migraine-related factors. METHOD: Migraineurs who visited a tertiary headache clinic and one of nine neurology clinics between May 2014 and November 2019 were studied. RESULT: Among the 4821 patients meeting the migraine criteria (International Classification of Headache Disorders, 3rd edition), 1038 (21.5%) patients experienced at least one premonitory symptom. The most common premonitory symptoms were neck stiffness, dizziness, yawning and drowsiness. The logistic regression analysis demonstrated that aura, photophobia, aggravation by routine physical activity, triggers, family history, depression, coffee consumption and physical exercise were associated with an increased probability of experiencing premonitory symptoms (p ≤ 0.001). The premonitory symptoms of migraine with and without aura differ in prevalence and most common symptoms. The cluster analysis revealed pairwise clustering of the following premonitory symptoms: Photophobia/phonophobia, concentration change/dysesthesia, loquacity/overactivity, yawning/drowsiness, fatigue/dizziness, and mood change/irritability. The correlation analysis of triggers and premonitory symptoms revealed that temperature change, environment change, sleep disorder, activity and stress were related to multiple premonitory symptoms, and that food, light, menstruation, alcohol and odor were related to special premonitory symptoms (p ≤ 0.001). CONCLUSION: The prevalence of premonitory symptoms among migraineurs in China is 21.5%. Some factors influence the probability of experiencing premonitory symptoms. Paired premonitory symptoms in the clustering analysis may share similar origins. Certain triggers associated with multiple premonitory symptoms may induce brain dysfunction; however, other triggers that overlap with corresponding special premonitory symptoms may be premonitory symptoms or a form of premonitory symptom.

Seeing others yawn selectively enhances vigilance: an eye-tracking study of snake detection.

While the origin of yawning appears to be physiologic, yawns may also hold a derived communicative function in social species. In particular, the arousal reduction hypothesis states that yawning signals to others that the actor is experiencing a down regulation of arousal and vigilance. If true, seeing another individual yawn might enhance the vigilance of observers to compensate for the reduced mental processing of the yawner. This was tested in humans by assessing how exposure to yawning stimuli alters performance on visual search tasks for detecting snakes (a threatening stimulus) and frogs (a neutral stimulus). In a repeated-measures design, 38 participants completed these tasks separately after viewing yawning and control videos. Eye-tracking was used to measure detection latency and distractor fixation frequency. Replicating previous evolutionary-based research, snakes were detected more rapidly than frogs across trials. Moreover, consistent with the view that yawning holds a distinct signaling function, there were significant interactions for both detection latency and distractor fixation frequency showing that vigilance was selectively enhanced following exposure to yawns. That is, after viewing videos of other people yawning, participants detected snakes more rapidly and were less likely to fixate on distractor frogs during trials. These findings provide the first experimental evidence for a social function to yawning in any species, and imply the presence of a previously unidentified psychological adaptation for preserving group vigilance.

Taste association capabilities differ in high- and low-yawning rats versus outbred Sprague-Dawley rats after prolonged sugar consumption.

Yawning is a stereotypical behavior pattern commonly associated with other behaviors such as grooming, sleepiness, and arousal. Several differences in behavioral and neurochemical characteristics have been described in high-yawning (HY) and low-yawning (LY) sublines from Sprague-Dawley (SD) rats that support they had changes in the neural mechanism between sublines. Differences in behavior and neurochemistry observed in yawning sublines could also overlap in processes needed during taste learning, particularly during conditioned taste aversion (CTA) and its latent inhibition. Therefore, the aim of this study was to analyze taste memory differences, after familiarization to novel or highly sweet stimuli, between yawning sublines and compare them with outbred SD rats. First, we evaluated changes in appetitive response during long-term sugar consumption for 14 days. Then, we evaluated the latent inhibition of CTA strength induced by this long pre-exposure, and we also measured aversive memory extinction rate. The results showed that SD rats and the two sublines developed similar CTA for novel sugar and significantly stronger appetitive memory after long-term sugar exposure. However, after 14 days of sugar exposure, HY and LY sublines were unable to develop latent inhibition of CTA after two acquisition trials and had a slower aversive memory extinction rate than outbreed rats. Thus, the inability of the HY and LY sublines to develop latent inhibition of CTA after long-term sugar exposure could be related to the time/context processes involved in long-term appetitive re-learning, and in the strong inbreeding that characterizes the behavioral traits of these sublines, suggesting that inbreeding affects associative learning, particularly after long-term exposure to sweet stimuli which reflects high familiarization.

Intermittent dietary supplementation with fish oil prevents high fat diet-induced enhanced sensitivity to dopaminergic drugs.

Eating a high fat diet can lead to obesity, type 2 diabetes, and dopamine system dysfunction. For example, rats eating high fat chow are more sensitive than rats eating standard chow to the behavioral effects (e.g., locomotion and yawning) of dopaminergic drugs (e.g., quinpirole and cocaine). Daily dietary supplementation with 20% (w/w) fish oil prevents high fat diet-induced enhanced sensitivity to quinpirole-induced yawning and cocaine-induced locomotion; however, doctors recommend that patients take fish oil just two to three times a week. To test the hypothesis that intermittent (i.e., 2 days per week) dietary supplementation with fish oil prevents high fat diet-induced enhanced sensitivity to quinpirole and cocaine, rats eating standard chow (17% kcal from fat), high fat chow (60% kcal from fat), and rats eating standard or high fat chow with 20% (w/w) intermittent (e.g., 2 days per week) dietary fish oil supplementation were tested once weekly with quinpirole [0.0032-0.32 mg/kg, intraperitoneally (i.p.)] or cocaine (1.0-17.8 mg/kg, i.p.) using a cumulative dosing procedure. Consistent with previous reports, eating high fat chow enhanced sensitivity of rats to the behavioral effects of quinpirole and cocaine. Intermittent dietary supplementation of fish oil prevented high fat chow-induced enhanced sensitivity to dopaminergic drugs in male and female rats. Future experiments will focus on understanding the mechanism(s) by which fish oil produces these beneficial effects.

Contagious itching is heightened in children with autism spectrum disorders.

The authors tested susceptibility to contagious itching, laughter, and yawning in 55 children with autism spectrum disorder (ASD), ages 8-14, and 106 typically developing (TD) children, ages 5-14. Children with ASD were less likely to yawn or laugh contagiously compared with TD peers, but showed increased susceptibility to contagious itching, under naturalistic conditions. Contagious yawning and laughter were positively correlated with emotional empathy in the TD group. In contrast, contagious itching showed no relationship to empathy, and was positively correlated with autism symptom severity in the ASD group. The authors explore the implications of these findings in terms of psychological theories about ASD.

Not all yawns tell the same story: The case of Tonkean macaques.

Here we show for the first time that the plasticity in morphology and duration of yawning in Macaca tonkeana can be associated with different functional contexts. Macaca tonkeana is classified as a tolerant macaque species characterized by social interactions minimally constrained by dominance rank or kinship. Tonkean macaques, as other egalitarian species, rely on a complex facial communicative system. We found that the degree of mouth opening (ranging from covered to uncovered tooth yawns) and the duration of yawning were not strictly dependent. The shortest uncovered tooth yawns were associated with an intense locomotor/physical activity and peaked immediately after stressful social events thus indicating an increase in arousal. In contrast, longer yawns, independently from teeth exposure, were primarily associated with a relaxed state of the subject. In conclusion, our study suggests that to explore the potential different functions of yawning, it is necessary to focus on the variability of its expression both in terms of morphology and duration, because not all yawns tell the same story.

Earlier than previously thought: Yawn contagion in preschool children.

Yawning is a primitive and stereotyped motor action involving orofacial, laryngeal, pharyngeal, thoracic and abdominal muscles. Contagious yawning, an involuntarily action induced by viewing or listening to others' yawns, has been demonstrated in human and several non-human species. Previous studies with humans showed that infants and preschool children, socially separated during video experiments, were not infected by others' yawns. Here, we tested the occurrence of yawn contagion in 129 preschool children (ranging from 2.5 to 5.5 years) belonging to five different classes by video recording them in their classrooms during the ordinary school activities. As it occurs in adult humans, children of all ages were infected by others' yawns within the 2 min after the perception of the stimulus. The yawn contagion occurred earlier than previously thought. For children, it appears that the natural social setting is more conducive to yawn contagion than the inherently artificial experimental approach. Moreover, children's gender did not affect the level of contagious yawning. The neural, emotional and behavioural traits of preschool children are probably not sufficiently mature to express variability between boys and girls; nevertheless, children appeared to be already well equipped with the 'neural toolkit' necessary for expressing yawn contagion.

A more secure and effective method for throat swab collection: The importance of adequate exposure of oral cavity in COVID-19 specimen collection.

OBJECTIVES: This study aims to propose a novel and effective throat swab collection method for coronavirus disease 2019 (COVID-19). METHODS: The subjects were randomly divided into two groups. The subjects were asked to open their mouth to make "ah" sound (traditional method) or simulate yawn (improved method) for throat swab collection. The usage of tongue depressor, collection time, adverse reactions and subjective discomfort (VAS score) were compared. The collection time, comprehensive indicators of adverse reactions and VAS score were also compared among three collectors. RESULTS: The tongue depressor was less used in the improved group (χ2 = 40.186, P < 0.01). The average collection time of the traditional group was 5.44 ± 2.97 and that of the improved group was 4.00 ± 2.31 (P < 0.01). The subjects in the improved group had fewer and milder adverse reactions. The VAS score of subjects in the improved group was lower than that in the traditional group (P < 0.01). Among different collectors, the collection time, comprehensive indicators of adverse reactions and VAS were the same as the overall trend. CONCLUSION: Simulating yawn is a safer and faster throat swab collection method.

Yawning in the history of psychiatry.

Yawning is a fascinating physiological behaviour that has been poorly addressed except in old medical books. Whereas the purpose of this behaviour is still not clearly identified, the ancient authors made it a clinical symptom, especially a psychological one. After presenting some current notions about yawning, we review publications on yawning written by physicians, from antiquity to the twentieth century, and, in particular, those dealing with psychological and psychiatric aspects.

Contagious yawning is not a signal of empathy: no evidence of familiarity, gender or prosociality biases in dogs.

Contagious yawning has been suggested to be a potential signal of empathy in non-human animals. However, few studies have been able to robustly test this claim. Here, we ran a Bayesian multilevel reanalysis of six studies of contagious yawning in dogs. This provided robust support for claims that contagious yawning is present in dogs, but found no evidence that dogs display either a familiarity or gender bias in contagious yawning, two predictions made by the contagious yawning-empathy hypothesis. Furthermore, in an experiment testing the prosociality bias, a novel prediction of the contagious yawning-empathy hypothesis, dogs did not yawn more in response to a prosocial demonstrator than to an antisocial demonstrator. As such, these strands of evidence suggest that contagious yawning, although present in dogs, is not mediated by empathetic mechanisms. This calls into question claims that contagious yawning is a signal of empathy in mammals.

Dopaminergic symptoms in migraine: A cross-sectional study on 1148 consecutive headache center-based patients.

BACKGROUND: Dopaminergic symptoms may be extremely pronounced in some migraine patients during the attack, representing a major source of disability. OBJECTIVES: We aimed to carefully characterize the clinical picture of migraine patients with dopaminergic symptoms in a large patients' population as a putative migraine endophenotype, allowing more precise disease management, treatment and outcome prediction. METHODS: We screened 1148 consecutive tertiary care episodic and chronic migraine patients with face-to-face interviews collecting thorough data on lifestyle, socio-demographic factors, and clinical migraine features. RESULTS: We identified 374 patients with migraine with dopaminergic symptoms (32.6%). The most frequent dopaminergic symptom was yawning followed by somnolence, nausea, vomiting, fatigue, mood changes and diuresis. Migraine patients with dopaminergic symptoms had longer attack duration (OR: 1.82; 95% CI: 1.41-2.36, p < 0.0001), more frequent osmophobia (OR: 2.01; 95% CI: 1.50-2.69, p < 0.0001), allodynia (OR: 1.43; 95% CI: 1.10-1.85, p = 0.0071) and unilateral cranial autonomic symptoms (OR: 1.31; 95% CI: 1.01-1.68, p = 0.045), but used less preventative treatments (OR: 0.74; 95% CI: 0.57-0.98, p = 0.033) than patients without dopaminergic symptoms. CONCLUSIONS: Migraine patients with dopaminergic symptoms are characterized by a full-blown, more disabling migraine. Dopaminergic system modulation should be carefully considered in individuals with migraine with dopaminergic symptoms for both acute and preventative treatments in future ad hoc designed studies.

Emotional contagion in children with autism spectrum disorder varies with stimulus familiarity and task instructions.

Although deficits in cognitive empathy are well established in individuals with autism spectrum disorder (ASD), the literature on emotional empathy, or emotional contagion, in individuals with ASD is sparse and contradictory. The authors tested susceptibility to contagious yawning and laughter in children with ASD (n = 60) and typically developing (TD) children (n = 60), ages 5-17 years, under various conditions, to elucidate factors that may affect emotional contagion in these populations. Although TD children showed equal amounts of emotional contagion across conditions, children with ASD were highly influenced by the familiarity of the target stimulus, as well as task instructions that encourage eye gaze to target. More specifically, children with ASD exhibited less contagious yawning and laughter than their TD peers except when their attention was explicitly directed to the eyes or (and even more so) when their parents served as the stimulus targets. The authors explore the implications of these findings for theories about the mechanisms underlying empathic deficits in ASD as well as the clinical implications of having parents involved in treatment.

Low relationship quality predicts scratch contagion during tense situations in orangutans (Pongo pygmaeus).

Primates show various forms of behavioral contagion that are stronger between kin and friends. As a result, behavioral contagion is thought to promote group coordination, social cohesion, and possibly state matching. Aside from contagious yawning, little is known about the contagious effect of other behaviors. Scratching is commonly observed during arousal and as such may play a role within group dynamics. While the Bornean orangutan (Pongo pygmaeus) is commonly considered the least social great ape, orangutans do engage in social interactions. Therefore, their social organization makes them a suitable case for studying the social function of behavioral contagion. Through behavioral observations of captive orangutans, we recorded all yawn and scratch events together with the corresponding behavior of all bystander group-members. As yawning was rarely observed, no conclusions could be drawn regarding this behavior. Scratching was contagious and occurred within 90 s after the triggering scratch. Specifically, orangutans showed increased scratch contagion when they had seen a weakly bonded individual scratch during tense contexts. When the orangutan had not seen the triggering scratch, the contagiousness of scratching was not affected by context or relationship quality. Our results indicate that behavioral contagion is not simply higher between individuals with stronger social relationships, but that the contagiousness of behaviors may vary based on the context and on social factors. We discuss these findings in light of an adaptive function that may reduce aggression.