Mutual medication in capuchin monkeys - Social anointing improves coverage of topically applied anti-parasite medicines

Histologic lesions of giant African millipedes (Archispirostreptus gigas) from a zoological institution

Histopathologic data of millipedes are scarce. Little is known about health and disease of these invertebrates despite their exhibition at zoological institutions and use in ecotoxicological studies. In a retrospective study of 69 zoo-housed giant African millipedes (Archispirostreptus gigas) submitted between 2018 and 2021, most deaths occurred during midwinter and in 2021. The most common lesion was inflammation (n = 55; 80%). Necrosis was seen concurrently in 31 (45%) millipedes and of these, bacteria (20; 29%) and fungi (7; 10%) were detected in lesions. Inflammation was seen in the head/collum (20; 29%), hemocoel (16; 23%), and appendages (9; 13%), specifically in perivisceral fat body (42; 61%), gut (16; 23%), tracheae (26; 38%), skeletal muscle (24; 35%), and ventral nerve (17; 25%). Inflammatory cell types and patterns included agranular hemocytes (61; 88%), granular hemocytes (39; 57%), and nodulation/encapsulation (47; 68%) often accompanied by melanization. The oral cavity or gut (ingestion), spiracles (inhalation), or cuticular defects were considered plausible routes of bacterial entry. Metazoan parasites (adult nematodes: 2, 3%; trematode ova: 2, 3%; and arthropods: 1, 1%) were associated with gut necrosis and inflammation in 5 millipedes. In addition, adult nematodes were noted in the gut of 4 millipedes without lesions. Neoplasia was not detected in any millipedes. Speculatively, environmental factors may have predisposed to disease, as most deaths occurred during winter months. Disease surveillance of millipedes is critical to optimize husbandry practices in zoo populations and investigate potential impacts of environmental degradation and climate change on wild millipedes.

Oxytocin and social gaze during a dominance categorization task in tufted capuchin monkeys

Visual attention to facial features is an important way that group-living primate species gain knowledge about others. However, where this attention is focused on the face is influenced by contextual and social features, and emerging evidence in Pan species suggests that oxytocin, a hormone involved in forming and maintaining affiliative bonds among members of the same group, influences social attention as measured by eye gaze. Specifically, bonobos tend to focus on conspecifics' eyes when viewing two-dimensional images, whereas chimpanzees focus more on the edges of the face. Moreover, exogenous oxytocin, which was hypothesized to increase eye contact in both species, instead enhanced this existing difference. We follow up on this to (1) determine the degree to which this Pan pattern generalizes across highly social, cooperative non-ape primates and (2) explore the impact of exogenously administered vs. endogenously released oxytocin in impacting this behavior. To do so, we tracked gaze direction on a computerized social categorization task using conspecific faces in tufted capuchin monkeys (Sapajus [Cebus] apella) after (1) exogenously administering intranasal oxytocin using a nebulizer or (2) inducing an endogenous increase in oxytocin using fur-rubbing, previously validated to increase oxytocin in capuchins. Overall, we did not find a general tendency in the capuchins to look toward the eyes or mouth, but we found that oxytocin was related to looking behavior toward these regions, albeit not in a straightforward way. Considering frequency of looking per trial, monkeys were more likely to look at the eye region in the fur-rubbing condition as compared to either the saline or exogenous oxytocin conditions. However, in terms of duration of looking during trials in which they did look at the eye region, monkeys spent significantly less time looking at the eyes in both oxytocin conditions as compared to the saline condition. These results suggest that oxytocin did not necessarily enhance eye looking in capuchins, which is consistent with the results from Pan species, and that endogenous and exogenous oxytocin may behave differently in their effect on how social attention is allocated.

Fur rubbing in <i>Plecturocebus cupreus</i> – an incidence of self-medication?

Abstract. Fur rubbing, i.e. rubbing a substance or an object into the pelage, has been described in numerous Neotropical primate species, including species of titi monkeys, but it seems to be a rare behaviour. Here we describe a fur rubbing event in a wild coppery titi monkey (Plecturocebus cupreus) with Psychotria sp. (Rubiaceae) leaves observed and videotaped during a field study on vigilance behaviour between September–December 2019 in the Peruvian Amazon. Plants of the genus Psychotria contain a great diversity of secondary metabolites and are often used in traditional medicine. We suggest that the fur rubbing was an act of self-medication. This is the first record of fur rubbing in coppery titi monkeys in almost 4400 h of observation accumulated over more than 20 years.

Urine washing in urban robust capuchin monkeys (Sapajus sp.): The relation with visitors

In primates, urine washing (UW) is a behavior in which individuals intentionally deposit urine on their bodies. Social and nonsocial hypotheses have been proposed to explain the adaptive function of this behavior. For capuchins, different functions have been assigned for UW, suggesting it as a flexible behavior, but studies have been mainly in captivity. However, no investigations have been performed in urban environments, where these animals can modify their behavior. Our goal was to study UW in a semi-provisioned group of an introduced unknown robust capuchin species (Sapajus sp.) living in a tiny urban fragment in Foz do Iguaçu, Brazil, where they have contact with humans. We assessed the influence of social (sexual, agonistic, and anointing behaviors) and environmental (temperature, relative air humidity, height of the monkeys in the trees, number of people present in the fragment, and human-monkey interactions) variables, the influence of behavior before and after UW, and the influence of sex-age classes, on the frequency of UW. We observed 75 records of UW in 300 h of observations, where urine was mostly deposited on hands and passed on to feet (95%). There were no significant differences in the frequency of the behavior between sex-age classes nor in the behaviors before and after UW. Around 50% of UW took place in the late morning and we found no correlation between UW and temperature, relative air humidity, nor the heights of the monkeys in the trees. However, we found a significant association between UW and the daily number of people in the fragment, but not between UW and human-monkey interactions, anointing, agonisms, and sexual behavior. Our study increases the scope of UW flexibility by identifying the presence of visitors affecting the occurrence of this behavior. We discussed different possibilities through which people could influence the capuchins to display UW.

The evolution of the human healthcare system and implications for understanding our responses to COVID-19

The COVID-19 pandemic has revealed an urgent need for a comprehensive, multidisciplinary understanding of how healthcare systems respond successfully to infectious pathogens-and how they fail. This study contributes a novel perspective that focuses on the selective pressures that shape healthcare systems over evolutionary time. We use a comparative approach to trace the evolution of care-giving and disease control behaviours across species and then map their integration into the contemporary human healthcare system. Self-care and pro-health environmental modification are ubiquitous across animals, while derived behaviours like care for kin, for strangers, and group-level organizational responses have evolved via different selection pressures. We then apply this framework to our behavioural responses to COVID-19 and demonstrate that three types of conflicts are occurring: (1) conflicting selection pressures on individuals, (2) evolutionary mismatches between the context in which our healthcare behaviours evolved and our globalized world of today and (3) evolutionary displacements in which older forms of care are currently dispensed through more derived forms. We discuss the significance of understanding how healthcare systems evolve and change for thinking about the role of healthcare systems in society during and after the time of COVID-19-and for us as a species as we continue to face selection from infectious diseases.

Wild Blonde Capuchins (Sapajus flavius) Perform Anointing Behaviour Using Toxic Secretions of a Millipede (Spirobolida: Rhinocricidae)

Defensive secretions of millipedes are remarkable for containing toxic quinones known to efficiently repell hematophagous arthropods. Here we show that Endangered blonde capuchin monkeys make use of such secretions. We (i) describe the anointing behavior performed by the monkeys (ii) identify the millipede species used in the process (iii) describe the volatile chemical composition of its secretion. The blonde capuchin monkeys selectively searched for millipedes hidden under the ground. We observed three bouts of anointing behavior, performed by 13 individuals of all age classes (from adults to independent infants), both solitarily (1 event) and socially (10 events). The only millipede species used by the monkeys is an undescribed species of the genus Poecilocricus (Spirobolida, Rhinocricidae). The volatile chemical composition of the secretions was predominantly comprised of a mixture of benzoquinones and hydroquinones. The social nature of the behavior and time of the observations (mosquito season), suggest that social bonding and mosquito avoidance is linked to the anointing behavior of the monkeys.

Scent anointing in mammals: functional and motivational insights from giant pandas

Although several mammals impregnate their fur with environmental odors, a phenomenon termed scent anointing or rubbing, the functional relevance of this behavior often is unclear. One theory is that scent anointing could be a form of scent matching with environmental odors to signal competitiveness and home range occupation. In this study we presented giant pandas with a range of odors to determine whether scent matching could provide a functional explanation for scent anointing in this species. We found that only a musk-based perfume elicited significantly more scent-anointing and scent-marking behavior than control. Males were also significantly more likely to scent-anoint and scent-mark than females. A preference for anointing, but not scent marking, when presented with peppermint (an insecticide) also was revealed. Our results suggest that giant pandas differentially scent-anoint with foreign odors to signal home range occupation, and possibly to repel ectoparasites. We also highlight how chemical signaling of resource-holding potential is likely to play an important role in determining competitive interactions between adult male giant pandas.

Why Care: Complex Evolutionary History of Human Healthcare Networks

One of the striking features of human social complexity is that we provide care to sick and contagious individuals, rather than avoiding them. Care-giving is a powerful strategy of disease control in human populations today; however, we are not the only species which provides care for the sick. Widespread reports occurring in distantly related species like cetaceans and insects suggest that the building blocks of care for the sick are older than the human lineage itself. This raises the question of what evolutionary processes drive the evolution of such care in animals, including humans. I synthesize data from the literature to evaluate the diversity of care-giving behaviors and conclude that across the animal kingdom there appear to be two distinct types of care-behaviors, both with separate evolutionary histories: (1) social care behaviors benefitting a sick individual by promoting healing and recovery and (2) community health behaviors that control pathogens in the environment and reduce transmission within the population. By synthesizing literature from psychology, anthropology, and biology, I develop a novel hypothesis (Hominin Pathogen Control Hypothesis) to explain how these two distinct sets of behaviors evolved independently then merged in the human lineage. The hypothesis suggests that social care evolved in association with offspring care systems whereas community health behaviors evolved as a type of niche construction. These two types of behaviors merged in humans to produce complex, multi-level healthcare networks in humans. Moreover, each type of care increases selection for the other, generating feedback loops that selected for increasing healthcare behaviors over time. Interestingly, domestication processes may have contributed to both social care and community health aspects of this process.

Anointing with commercial insect repellent by free-ranging Cebus capucinus in Manuel Antonio National Park, Quepos, Costa Rica

Fur rubbing or anointing is a well known behavior in capuchin monkeys (Cebus and Sapajus), and may have medicinal and/or social functions. Observations of anointing in capuchins have recorded the application of substances derived from both plants (orange, onion, garlic, citronella, and lemongrass) and animals (ants and millipedes). The present study reports on anointing behavior in free-ranging white-headed capuchins, Cebus capucinus, which involved a commercial insect repellent. After looting a bottle of repellent from the bag of a visitor to the Manuel Antonio National Park in Costa Rica, an adult male bit open the bottle and rubbed the leaking liquid over its entire body, focusing mainly on its belly. Other members of the group rubbed themselves against the male's body and were eventually able to retrieve the bottle of repellent and anoint themselves. The repellent is composed mainly of extracts of eucalyptus and citronella. The capuchins may have been attracted by the strong citric scent of the citronella, which is known to stimulate fur-rubbing behavior in these monkeys. This is reinforced by the fact that the sequence of events was quite distinct from that associated with an earlier event, in which a juvenile male looted, tasted, and then discarded a stick of lip gloss and a tube of sunblock. Overall, the observations indicate that the citric scent of the repellent was attractive to the capuchins, especially in comparison with other man-made substances. As the animals partially ingested all the substances, there is clearly a need for more effective regulation of the contact between animals and visitors in the park.

Wound treatment and selective help in a termite-hunting ant

Open wounds are a major health risk in animals, with species prone to injuries likely developing means to reduce these risks. We therefore analysed the behavioural response towards open wounds on the social and individual level in the termite group-hunting ant Megaponera analis During termite raids, some ants get injured by termite soldiers (biting off extremities), after the fight injured ants get carried back to the nest by nest-mates. We observed treatment of the injury by nest-mates inside the nest through intense allogrooming at the wound. Lack of treatment increased mortality from 10% to 80% within 24 h, most likely due to infections. Wound clotting occurred extraordinarily fast in untreated injured individuals, within 10 min. Furthermore, heavily injured ants (loss of five extremities) were not rescued or treated; this was regulated not by the helper but by the unresponsiveness of the injured ant. Interestingly, lightly injured ants behaved 'more injured' near nest-mates. We show organized social wound treatment in insects through a multifaceted help system focused on injured individuals. This was not only limited to selective rescuing of lightly injured individuals by carrying them back (thus reducing predation risk), but, moreover, included a differentiated treatment inside the nest.

The Extended Genotype: Microbially Mediated Olfactory Communication

Microbes are now known to influence inter- and intraspecific olfactory signaling systems. They do so by producing metabolites that function as odorants. A unique attribute of such odorants is that they arise as a product of microbial-host interactions. These interactions need not be mutualistic, and indeed can be antagonistic. We develop an integrated ecoevolutionary model to explore microbially mediated olfactory communication and a process model that illustrates the various ways that microbial products might contribute to odorants. This novel approach generates testable predictions, including that selection to incorporate microbial products should be a common feature of infochemicals that communicate identity but not those that communicate fitness or quality. Microbes extend an individual's genotype, but also enhance vulnerability to environmental change.

Potential self-medication using millipede secretions in red-fronted lemurs: combining anointment and ingestion for a joint action against gastrointestinal parasites?

Self-anointing, referring to the behaviour of rubbing a material object or foreign substance over different parts of the body, has been observed in several vertebrate species, including primates. Several functions, such as detoxifying a rich food source, social communication and protection against ectoparasites, have been proposed to explain this behaviour. Here, we report observations of six wild red-fronted lemurs (Eulemur rufifrons) of both sexes and different age classes anointing their perianal-genital areas and tails with chewed millipedes. Several individuals also ingested millipedes after prolonged chewing. In light of the features of the observed interactions with millipedes, and the nature and potential metabolic pathways of the released chemicals, we suggest a potential self-medicative function. Specifically, we propose that anointing combined with the ingestion of millipedes' benzoquinone secretions by red-fronted lemurs may act in a complementary fashion against gastrointestinal parasite infections, and more specifically Oxyuridae nematodes, providing both prophylactic and therapeutic effects.

Self-anointing behaviour in captive titi monkeys (Callicebus spp.)

Self-anointing behaviour using Bauhinia sp. was reported in two captive titi monkeys (Callicebus coimbrai and Callicebus barbarabrownae). The study was carried out from October 2013 to May 2014 during an experimental study investigating the gut passage time of these individuals at the Getúlio Vargas Zoobotanical Park, north-eastern Brazil. Although leaves, petioles and flowers of Bauhinia contain chemical substances that could affect the presence of ectoparasites, it is unclear if titi monkeys demonstrate self-anointing behaviour as a method of self-medication. However, due to the presence of large glands in C. coimbrai and C. barbarabrownae chests, and the high frequency of occurrence observed for the adult male, we cautiously suggest that the use of Bauhinia may be linked to olfactory communication.

Fur-rubbing with Piper leaves in the San Martín titi monkey, Callicebus oenanthe

We report observations on fur-rubbing with leaves from Piper aduncum by a San Martín titi monkey, Callicebus oenanthe. Fur-rubbing occurred during the transition from the dry to the rainy season in a titi monkey group living in a forest fragment in the Moyobamba region of Peru. Since Piper leaves include very potent compounds that may affect ectoparasites, we tentatively interpret the observed fur-rubbing as self-medication.