How mangabey molar form differs under routine vs. fallback hard-object feeding regimes.

Background: Components of diet known as fallback foods are argued to be critical in shaping primate dental anatomy. Such foods of low(er) nutritional quality are often non-preferred, mechanically challenging resources that species resort to during ecological crunch periods. An oft-cited example of the importance of dietary fallbacks in shaping primate anatomy is the grey-cheeked mangabey Lophocebus albigena. This species relies upon hard seeds only when softer, preferred resources are not available, a fact which has been linked to its thick dental enamel. Another mangabey species with thick enamel, the sooty mangabey Cercocebus atys, processes a mechanically challenging food year-round. That the two mangabey species are both thickly-enameled suggests that both fallback and routine consumption of hard foods are associated with the same anatomical feature, complicating interpretations of thick enamel in the fossil record. We anticipated that aspects of enamel other than its thickness might differ between Cercocebus atys and Lophocebus albigena. We hypothesized that to function adequately under a dietary regime of routine hard-object feeding, the molars of Cercocebus atys would be more fracture and wear resistant than those of Lophocebus albigena. Methods: Here we investigated critical fracture loads, nanomechanical properties of enamel, and enamel decussation in Cercocebus atys and Lophocebus albigena. Molars of Cercopithecus, a genus not associated with hard-object feeding, were included for comparison. Critical loads were estimated using measurements from 2D µCT slices of upper and lower molars. Nanomechanical properties (by nanoindentation) and decussation of enamel prisms (by SEM-imaging) in trigon basins of one upper second molar per taxon were compared. Results: Protocone and protoconid critical fracture loads were significantly greater in Cercocebus atys than Lophocebus albigena and greater in both than in Cercopithecus. Elastic modulus, hardness, and elasticity index in most regions of the crown were greater in Cercocebus atys than in the other two taxa, with the greatest difference in the outer enamel. All taxa had decussated enamel, but that of Cercocebus atys uniquely exhibited a bundle of transversely oriented prisms cervical to the radial enamel. Quantitative comparison of in-plane and out-of-plane prism angles suggests that decussation in trigon basin enamel is more complex in Cercocebus atys than it is in either Lophocebus albigena or Cercopithecus cephus. These findings suggest that Cercocebus atys molars are more fracture and wear resistant than those of Lophocebus albigena and Cercopithecus. Recognition of these differences between Cercocebus atys and Lophocebus albigena molars sharpens our understanding of associations between hard-object feeding and dental anatomy under conditions of routine vs. fallback hard-object feeding and provides a basis for dietary inference in fossil primates, including hominins.

Golden-bellied mangabeys (Cercocebus chrysogaster) exhibit a larger home range and longer travel distances than those of bonobos (Pan paniscus) at LuiKotale, Democratic Republic of the Congo.

Primate ranging behavior is associated with numerous social and ecological correlates. Interspecific comparisons of ranging behavior can therefore provide insight into the socio-ecological conditions that characterize a species' niche within its community. We provide the first description of ranging behavior in golden-bellied mangabeys (Cercocebus chrysogaster), using sympatric bonobos (Pan paniscus) as a comparison. Over 6 months, we recorded GPS tracks at 1- and 5-min intervals from one habituated golden-bellied mangabey group and two habituated bonobo communities at LuiKotale, central Democratic Republic of the Congo. We compared estimates of home range size, time spent at different elevations, and hourly travel distances between species. We modeled daily travel distances against total monthly rainfall to investigate seasonal variation in daily ranging. The golden-bellied mangabey home range was similarly sized or larger than each of the two bonobo communities at LuiKotale across estimation methods. Mangabeys visited more of their range per day and spent more time in terra firma forest and less time in swamps than bonobos. Mangabeys traveled significantly farther per day and during midday hours than bonobos, but travel distances did not relate to monthly rainfall in either species. Golden-bellied mangabeys exhibited wide daily ranging behavior that more closely resembled that of sympatric bonobos than other Cercocebus species. Large homes ranges in mangabeys are likely influenced by food availability in terra firma forest, especially as groups appear to travel long distances between fruit trees and terrestrial food patches. Maximizing daytime activity may help mangabeys avoid competition from heterospecifics and indicates temporal niche partitioning in this primate community.

Social factors drive vocal exchanges in red-capped mangabeys (Cercocebus torquatus).

Of all the calls made by non-human primates, the function of short-distance contact calls has largely remained to be determined. These calls are the most frequent in the repertoire and are most often exchanged between individuals in a non-random way. To our knowledge, no study has ever examined how vocal exchanges are structured in red-capped mangabeys (Cercocebus torquatus), a semi-terrestrial monkey living in the African forest with a complex semi-tolerant/semi-despotic social system. Our goal was to assess the organization of contact call exchanges in this species and their relationship with individual and social factors such as age, affinity, and hierarchy. Therefore, we observed several captive groups of red-capped mangabeys and collected data on vocal behavior, as well as grooming, agonistic behavior, and spatial proximity. We defined a vocal exchange in this species as a series of contact calls made by two or more individuals within a maximum inter-caller interval of 2 s. At the individual level, the higher the individual's hierarchical rank, the less they initiated exchanges. Furthermore, the most socially integrated individuals had a longer average response time than the less integrated ones. At the dyadic level, preferred exchange partners were individuals often observed near one other or individuals most distant in age. Also, the further apart two individuals were in the dominance hierarchy, the shorter the response time. Our results support both the social bonding hypothesis and a modulating key role of the dominance hierarchy on the social use of contact calls, which is in line with the social style of this species.

Familiarity modulates both intra- and interspecific yawn contagion in red-capped mangabeys.

Yawn contagion (YC) is, compared to spontaneous yawning, an evolutionary recent phenomenon probably linked to behavioral synchronization in highly social species that is more likely when it involves familiar subjects. Here, we investigate for the first time in monkeys which factors modulate intra- and interspecific YC. Through an experimental approach, we exposed 17 red-capped mangabeys to video stimuli (Yawn vs Control) depicting familiar/unfamiliar red-capped mangabeys and humans, and unfamiliar hamadryas. We found that mangabeys yawned more often in response to Yawn than Control videos independently from the species depicted, demonstrating both intra- and interspecific YC in the tested species. Moreover, both mangabey and human familiar yawning stimuli evoked a stronger yawning response in the subjects compared to the unfamiliar counterparts. Neither the amount of time spent looking frontally at the screen (probability of stimulus perception) nor the levels of self-directed behaviors (a proxy of anxiety) accounted for the results. In conclusion, we provide the first evidence that in non-human primate familiarity modulates both intra- and inter-specific YC. Stimuli emitted by familiar faces somehow ease the mechanisms underlying YC, and this modulation can also apply to heterospecific subjects when previous shared experiences provide the prerequisites for the development of social bonds.

Intentional gestural communication amongst red-capped mangabeys (Cercocebus torquatus).

Apes, human's closest living relatives, are renowned for their intentional and highly flexible use of gestural communication. In stark contrast, evidence for flexible and intentional gestural communication in monkeys is scarce. Here, we investigated the intentionality and flexibility of spontaneous gesture use in red-capped mangabeys (Cercocebus torquatus). We applied established methods used in ape gesture research to analyse whether the body acts produced by a total of 17 individuals living in three different groups in captivity qualified as intentionally produced gesture instances. Results showed that signallers showed all hallmarks of intentionality during the production of 20 out of a total of 21 different types of body acts. These were only produced in the presence of other individuals, and the monkeys showed audience checking, sensitivity to the attentional states of recipients, adjustment of signal modality, and response waiting relative to their production. Moreover, in case of communication failure, the monkeys showed goal persistence, and regarding the production contexts they showed some signs of means-ends dissociation. Therefore, these monkeys are capable of flexible and intentional gestural communication and use this to communicate with conspecifics. Our results corroborate recent findings showing that intentional gestural communication was already present in the monkey lineage of catarrhine primates. We discuss our results in light of the comparative approach towards human language evolution and highlight our finding that these monkeys also showed flexible and intentional use of four 'free' manual gesture types.

Maximum longevity and juvenile mortality in zoo-housed mangabeys.

Little is known about the biology of grey-cheeked and black crested mangabeys (Lophocebus albigena and Lophocebus aterrimus, respectively). As these primates face threats in the wild, well-monitored zoo-housed populations with up to date registries are becoming increasingly valuable to acquire species knowledge and to support conservation efforts. We used international studbooks to extract demographic and genetic information on 519 mangabeys to investigate how life history and parent-related variables influence maximum longevity and juvenile mortality. Generalized linear mixed models, as well as survival analyses, were applied. Results showed that females lived significantly longer than males, which is not uncommon in primates. Furthermore, our results indicated that the maximum longevity is lower for individuals living in European zoos versus individuals from North American zoos, which may be due to a combination of environmental differences and potential founder effects. We also show that the maternal maximum longevity is positively related to the maximum longevity of the offspring, which may be explained by the inheritance of "good genes". However, the age of the mother at the moment of birth was negatively related to the maximum longevity of the offspring, which contradicts literature that states that, in primates, more experienced and thus older mothers will raise their offspring better than less experienced mothers. Instead, it is more likely that an "optimal age range" exists for breeding mothers. Our study provides insights into the population biology of captive mangabeys and may be helpful for identifying future research priorities to optimize primate health and welfare directly ex situ, and indirectly in situ.

Biomechanical correlates of zygomaxillary-surface shape in papionin primates and the effects of hard-object feeding on mangabey facial form.

Extant African papioninans are distinguished from macaques by the presence of excavated facial fossae; however, facial excavation differs among taxa. Mangabeys (Cercocebus, Rungwecebus, and Lophocebus) exhibit fossae that invade the zygomatic forming pronounced suborbital fossae (SOFs). Larger-bodied Papio, Mandrillus, and Theropithecus have lateral rostral fossae with minimal/absent suborbital fossae. Because prior studies have shown that mangabeys exhibit adaptations to anterior dental loading (e.g., palatal retraction), it is plausible that mangabey SOFs represent structural accommodation to masticatory-system shape rather than facial allometry, as commonly hypothesized. We analyzed covariation between zygomaxillary-surface shape, masticatory-system shape, and facial size in 141 adult crania of Macaca fascicularis, Papio kindae, Cercocebus, and Lophocebus. These taxa represent the range of papionin SOF expression while minimizing size variation (narrow allometry). Masticatory-system landmarks (39) registered palate shape, bite points, masticatory muscle attachments, and the temporomandibular joint. Semilandmarks (450) captured zygomaxillary-surface shape. Following Procrustes superimposition with semilandmark sliding and principal components analyses, multivariate regression was used to explore allometry, and two-block partial least-squares analyses (within-configuration and separate-blocks) were used to examine covariation patterns. Scores on principal components 1-2 and the first partial least-square (PLS1) separate mangabeys from Macaca and Papio. Both zygomaxillary-surface shape and masticatory-system shape are correlated with size within taxa and facial morphotypes; however, regression distributions indicate morphotype shape differences are non-allometric. PLS1 accounts for ∼95% of shape covariance (p < 0.0001) and shows strong linear correlations (r-PLS = âˆ¼0.95, p < 0.0001) between blocks. Negative PLS1 scores in mangabeys reflect deep excavation of the suborbital malar surface, palatal retraction, and anterior displacement of jaw adductor muscles and the temporomandibular joint. Neither PC1 nor PLS1 scores ordinate specimens by facial size. Taken together, these results fail to support the allometric hypothesis but suggest that mangabey zygomaxillary morphology is closely linked with adaptations to hard-object feeding.

Facial displays in red-capped mangabeys (Cercocebus torquatus): Repertoire, social context, and potential intentionality.

Primate communication relies strongly on the visual modality, notably through the production of a wide range of expressive facial signals. We investigated here the facial display repertoire of a relatively little-studied cercopithecid species, red-capped mangabeys (Cercocebus torquatus), and questioned whether their facial displays were dependent on social contexts and accompanied by indices of intentionality. Although the dual intentional and emotional use of apes' facial expressions has recently been suggested, the question of whether monkeys produce facial expressions intentionally to communicate remains open. We described 6 facial displays produced by captive red-capped mangabeys in social contexts. They are based on movements of the mouth, eyebrows, and ears, possibly graded in intensity and produced independently or in combination. We showed that most of the facial displays were produced preferentially in specific social contexts and that repertoires varied with subjects' characteristics, highlighting the communicative function of these displays. Moreover, behavioral markers of intentionality commonly used in gestural studies were found to accompany the production of some of the facial signals observed. Particularly, playful "open mouth" appeared strongly associated with intentionality indices, as previously noticed in ape species. All other facial displays, except yawns, did not exhibit all defined intentional indices but were, at least, directed toward a recipient. Interestingly, yawns presented different variants of intensity associated presumably with different social functions. Altogether, these results emphasize the communicative function of red-capped mangabeys' facial displays and provide a basis for further research on their intentional communication. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

White-naped mangabeys' viable insurance population within European Zoo Network.

The success and viability of an ex-situ conservation program lie in the establishment and potential maintenance of a demographically and genetically viable insurance population. Such population reserve may support reintroduction and reinforcement activities of wild populations. White-naped mangabeys are endangered restricted-range African primates which have experienced a dramatic population decrease in their natural habitats over the last few decades. Since 2001, some European zoos singularly monitor an ex-situ population aiming to seek the recovery of the current wild population. The aim of the present paper is to evaluate the genetic status and population demographics of European zoo-captive white-naped mangabeys based on pedigree data. The captive population is gradually growing and preserves specific reproductive and demographic parameters linked to the species. The intensive management program that is implemented has brought about the minimization of inbreeding and average relatedness levels, thus maintaining high levels of genetic diversity despite the existence of fragmented populations. This finding suggests white-naped mangabey ex-situ preservation actions may be a good example of multifaceted conservation throughout studbook management which could be used as a model for other ex-situ live-animal populations.

Red-capped mangabeys (Cercocebus torquatus) adapt their interspecific gestural communication to the recipient's behaviour.

Sensitivity to recipient's attention and responsiveness are critical markers of intentional communication. Although previous research showed that ape gestures can be intentional, few studies have yet addressed this question concerning monkeys. Here, we characterise the effect of a recipient's presence, attentional state and responsiveness on the interspecific gestural communication of captive red-capped mangabeys (Cercocebus torquatus). Previous reports showed that they produced learnt begging gestures towards a human recipient preferentially when the latter was facing them. We used here a novel setup that allows subjects to move around an experimenter and to use different modalities (visual and acoustic) to communicate. We found that when the recipient was not facing them, mangabeys moved to a position in the visual field of their recipient rather than using attention-getters. Interestingly, unlike apes, they did not elaborate their communication visually or acoustically when the experimenter did not respond favourably to their begging. However, our results may suggest that begging gestures were goal-directed, since mangabeys inhibited them when the experimenter was not available to answer immediately (i.e. give a reward). Overall, red-capped mangabeys' interspecific visual communication presented intentionality features, but their use of begging gestures was less flexible than that of great apes in similar situations.

Estimating the population size of the Sanje mangabey (Cercocebus sanjei) using acoustic distance sampling.

The Sanje mangabey (Cercocebus sanjei) is endemic to the Udzungwa Mountains, Tanzania, and is classified as Endangered due to its putatively declining population size, habitat degradation and fragmentation. Previous population size estimates have ranged from 1,350 to 3,500 individuals, with the last direct survey being conducted 15 years before the present study. Previous estimates are now thought to have underestimated the population due to a limited knowledge of group and habitat size, nonsystematic approaches and the use of visual methods that are not suitable for surveying the Sanje mangabey with its semi-terrestrial and elusive behaviors. We used an acoustic survey method with observers recording the distinctive "whoop-gobble" vocalization produced by mangabeys and point transect distance sampling to model a detection function and estimate abundance. Twenty-eight surveys were conducted throughout the two forests where Sanje mangabeys are found: Mwanihana forest in the Udzungwa Mountains National Park (n = 13), and the Uzungwa Scarp Nature Reserve (n = 15). Group density was found to be significantly lower in the relatively unprotected Uzungwa Scarp forest (0.15 groups/km2 ; 95% CI: 0.08-0.27) compared to the well-protected Mwanihana forest (0.29 groups/km2 ; 95% CI: 0.19-0.43; p = .03). We estimate that there are 1,712 (95% CI: 1,141-2,567) individuals in Mwanihana and 1,455 (95% CI: 783-2,702) in the Uzungwa Scarp, resulting in a total population size of 3,167 (95% CI: 2,181-4,596) individuals. The difference in group density between sites is likely a result of the differing protection status and levels of enforcement between the forests, suggesting that protection of the Uzungwa Scarp should be increased to encourage recovery of the population, and reduce the threat of degradation and hunting. Our results contribute to the reassessment of the species' IUCN Red List status and informing management and conservation action planning.

Structural Basis for a Species-Specific Determinant of an SIV Vif Protein toward Hominid APOBEC3G Antagonism.

Primate lentiviruses encode a Vif protein that counteracts the host antiviral APOBEC3 (A3) family members. The adaptation of Vif to species-specific A3 determinants is a critical event that allowed the spillover of a lentivirus from monkey reservoirs to chimpanzees and subsequently to humans, which gave rise to HIV-1 and the acquired immune deficiency syndrome (AIDS) pandemic. How Vif-A3 protein interactions are remodeled during evolution is unclear. Here, we report a 2.94 Å crystal structure of the Vif substrate receptor complex from simian immunodeficiency virus isolated from red-capped mangabey (SIVrcm). The structure of the SIVrcm Vif complex illuminates the stage of lentiviral Vif evolution that is immediately prior to entering hominid primates. Structure-function studies reveal the adaptations that allowed SIVrcm Vif to antagonize hominid A3G. These studies show a partitioning between an evolutionarily dynamic specificity determinant and a conserved protein interacting surface on Vif that enables adaptation while maintaining protein interactions required for potent A3 antagonism.

Haemogram and Serum Biochemical Values of Four Indigenous Species of Monkeys in South West Nigeria.

Haematological and serum biochemical values are useful guides and biomarkers in health and diseases for reaching a diagnosis, estimating disease prognosis and monitoring treatment progress, in mammals. Reference ranges for some parameters differ among species of mammals and between sexes within a species. There is dearth of information on standard reference value for blood parameters for Nigerian indigenous monkeys. Whole blood and serum samples obtained from 50 apparently healthy adult monkeys in both captivity and from the wild in southwest Nigeria were subjected to haematology and serum biochemistry to obtain preliminary reference values for haematological and serum biochemical analytes for Cercocebus sebaeus (Green monkey), Cercopithecus mona (Mona monkey), Erythrocebus patas (Patas monkey) and Papio anubis (Anubis baboon). Numerical data were summarized as mean and standard deviation and subjected to statistical analysis; Student t test and analysis of variance, to compare values of blood parameters obtained between species and gender. A p-value less than 0.05 was considered significant. The hematocrit of male animals were significantly higher than that of females (P=0.01) in all the 4 species studied but there was no significant difference in other blood parameters such as total white blood cell and the differential counts, platelet count, serum aspartate transferase, alanine transferase, alkaline phosphatase, total plasma protein, albumin, and globulin concentrations between the sexes. Generally, there was no significant difference between total white blood cell and the differential counts, hematocrit, red cell count, haemoglobin concentration, platelet count, serum aspartate transferase, alanine transferase, alkaline phosphatase, total plasma protein, albumin, and globulin concentrations among the monkey species.

Maternal Care in Free-Ranging Arboreal Grey-Cheeked Mangabeys (Lophocebus albigena johnstoni) in Kibale National Park, Uganda.

Maternal styles have been intensively studied in a variety of terrestrial species of primates, but far less in arboreal species. However, to have a balanced view of the evolution of maternal care, it is necessary to investigate this behaviour in the context of habitat. Here, we investigate whether the mother's parity, age and dominance rank, as well as the infant's age and sex, influence maternal care and mother-infant proximity in arboreal grey-cheeked mangabeys (Lophocebus albigena). We observed 13 mother-infant dyads in four free-ranging groups for 6 months. Our main finding is that maternal care is a dynamic process affected by a mix of mothers' and infants' characteristics. We found that first-time mothers spent more time watching their infants than multiparous mothers, who carried, groomed and protected their infants more often. We also found that low-ranking mothers prevented their infants from leaving them more often than did high-ranking mothers. Moreover, mothers adjusted their care as infants became older. They groomed and protected female infants more than male infants, behaviours common in female-bonded species. Our study shows the ever-changing dynamics of maternal care related to infant age and highlights the role of the mother's parity and rank in this process.

Group movements in response to competitors' calls indicate conflicts of interest between male and female grey-cheeked mangabeys.

Long-distance vocalizations mediate spacing patterns by allowing groups to choose whether to draw close enough to a neighbor to initiate a short-range interaction. It is unclear, however, whether the patterning of calls and the resulting movements are invariant or change in response to social and ecological variables. In this study, we compare the impact of long-distance calls on neighboring groups' movements in two populations of grey-cheeked mangabeys (Lophocebus albigena) in Uganda, which differed widely in group density and food availability. We monitored movement responses of target groups to both naturally occurring and experimentally simulated "whoop-gobble" vocalizations of neighboring adult males to test whether responses indicated mate and food defense. When defending access to fertile females, males might coerce group members to move away from neighboring males; when defending fitness-limiting food resources, however, groups might approach and attempt to evict neighbors. Controlling for pre-call movement prior to the vocalization, we found no difference in group responses between the low- and high-density populations, and little support for either form of defense. Mangabey groups generally continued moving in their original direction, albeit at a slower pace, and deviations from this pattern were predictable: they avoided nearby callers but approached distant callers; they approached if the caller was in the area where home ranges overlapped; and approached when their own group contained multiple peak-estrous females. The effect of multiple fertile females potentially indicates a breakdown of male control as a result of within-group intrasexual mating competition, and greater-than-expected female control over travel movements. As suspected, grey-cheeked mangabeys use neighbors' long-distance calls to maintain a spatial buffer between groups but changes in group movements indicate a conflict between male and female interests.

First molecular identification of Buxtonella ciliates from captive-bred mangabeys (Cercocebus torquatus) from China.

Buxtonella species are large cyst-forming ciliates that infect ruminants and monkeys, and are morphologically similar to Balantidium coli ciliates that infect pigs, humans, monkeys, and other animals. In this study, we isolated spherical cysts of ciliates that were similar to those of Balantidium and Buxtonella species within collared mangabeys (Cercocebus torquatus) from the Wangcheng Zoo of Luoyang in the Henan Province of central China. The cysts were further identified and designated as belonging to the Buxtonella monkey genotype based on molecular analyses of 18S rRNA, 5.8S rRNA, and ITS1-5.8S rRNA-ITS2 genetic markers. To our knowledge, this is the first report of Buxtonella monkey genotype within monkeys in China. These results will help clarify the classification of species of cyst-forming ciliate infections in monkeys.

Surgical Treatment of Recurrent Rectal Prolapse in an Adult Female Black-crested Mangabey (Lophocebus aterrimus) by Colopexy.

A 13-y-old, multiparous female black-crested mangabey (Lophocebus aterrimus) underwent surgical treatment for chronically recurring rectal prolapse by laparotomy and subsequent colopexy. Initially, a laparoscopic approach was attempted but was converted to an open approach after intraabdominal adhesions were noted. The colopexy was performed through a ventral midline incision, with no complications intraoperatively or postoperatively. The predisposing factors responsible for the development of this condition likely were related to pelvic floor weakness due to multiple past pregnancies. Transport-associated stressors likely contributed to the acute worsening of this patient's condition. Rectal prolapse is a common condition in laboratory-housed NHP. This case report describes an effective surgical treatment for recurring or otherwise nonreducible rectal prolapse in these species.

Gastrointestinal protists and helminths of habituated agile mangabeys (Cercocebus agilis) at Bai Hokou, Central African Republic.

Infectious diseases including those caused by parasites can be a major threat to the conservation of endangered species. There is thus a great need for studies describing parasite infections of these species in the wild. Here we present data on parasite diversity in an agile mangabey (Cercocebus agilis) group in Bai Hokou, Dzanga-Sangha Protected Areas (DSPA), Central African Republic. We coproscopically analyzed 140 mangabey fecal samples by concentration techniques (flotation and sedimentation). Agile mangabeys hosted a broad diversity of protistan parasites/commensals, namely amoebas (Entamoeba spp., Iodamoeba buetschlli), a Buxtonella-like ciliate and several parasitic helminths: strongylid and spirurid nematodes, Primasubulura sp., Enterobius sp., and Trichuris sp. Importantly, some of the detected parasite taxa might be of potential zoonotic importance, such as Entamoeba spp. and the helminths Enterobius sp., Trichuris sp., and strongylid nematodes. Detailed morphological examination of ciliate cysts found in mangabeys and comparison with cysts of Balantioides coli from domestic pigs showed no distinguishing structures, although significant differences in cyst size were recorded. Scanning or transmission electron microscopy combined with molecular taxonomy methods are needed to properly identify these ciliates. Further studies using molecular epidemiology are warranted to better understand cross-species transmission and the zoonotic potential of parasites in sympatric non-human primates and humans cohabiting DSPA.

Decision-making under risk of gain in young children and mangabey monkeys.

In contrast to human adults, risk proneness in the gain domain is usually observed in both young children and non-human primates. It is currently unclear what mechanism might be underlying such economic preferences. We investigated decision-making under risk of gain in toddlers and monkeys. The choices of 2.5-year-old children and red-capped mangabeys (Cercocebus torquatus torquatus) were examined in a gambling task for food reward in which participants have to choose between two options, a secure option and a risky option. In contrast to monkeys, toddlers showed a strong preference for the risky option over the safe option. In order to test the hypothesis that risky choices in participants reflect inhibitory control difficulties, toddlers and mangabeys were presented in Experiment 2 with a situation analogous to that used in Experiment 1 except for the fact that the opaque cover under which was placed the secure option was replaced by a transparent cover. In this second experiment, toddlers continued to show a preference for the risky option over the safe option. In contrast, mangabeys showed a preference for the safe option over the risky option in Trial 1 but they shifted their economic preferences in Trial 2. We argue that decision-making strategies under risk of gain in both toddlers and mangabeys (a) do not reflect poor behavioral control and (b) are not reducible to perception-action couplings.