Wild Capuchin Monkeys Research Articles

Toxic tasting: how capuchin monkeys avoid grasshoppers’ chemical defenses

Platyrrhines consume many species of arthropods in the order Orthoptera. Some species of orthopterans can produce chemical defenses that render them toxic or unpalatable and thus act as predator deterrents. These species include the stick grasshoppers (family Proscopiidae), which are widely distributed in the Caatinga biome in northeastern Brazil, which comprises part of the distribution of capuchin monkeys. Capuchin monkeys are omnivores and consume a wide variety of foods, including unpleasant-tasting, potentially toxic items, which they need to learn how to process. We describe the processing of stick grasshoppers (Stiphra sp.) by wild capuchin monkeys (Sapajus libidinosus) that live in Serra da Capivara National Park, Brazil, and compare how individuals of different age classes handle these potentially toxic food items. S. libidinosus predominantly avoided consuming the digestive tract, which contains toxic compounds, when feeding on stick grasshoppers. Immatures took longer than adults to process the stick grasshoppers, indicating that capuchins need to learn how to process the toxic digestive tract of these prey to avoid consuming it.

Wild capuchin monkeys use stones and sticks to access underground food

Primates employ different tools and techniques to overcome the challenges of obtaining underground food resources. Humans and chimpanzees are known to tackle this problem with stick tools and one population of capuchin monkeys habitually uses stone tools. Although early hominids could have used stones as digging tools, we know little about when and how these could be useful. Here, we report a second primate population observed using stone tools and the first capuchin monkey population to habitually use the ‘stick-probing’ technique for obtaining underground resources. The bearded capuchin monkeys (Sapajus libidinosus) from Ubajara National Park, Brazil, use ‘hands-only’ and ‘stone-digging’ techniques for extracting underground storage organs and trapdoor spiders. Males also use ‘stick-probing’ and ‘stone-stick’ techniques for capturing trapdoor spiders. Tool use does not increase success in obtaining these resources. Stone-digging is less frequent in this population than in the only other known population that uses this technique. Females use stones in a lower proportion of their digging episodes than males in both populations. Ecological and cultural factors potentially influence technique choice and sex differences within and between populations. This population has a different pattern of underground food exploration using tools. Comparing this population with others and exploring the ecological and cultural factors under which capuchin monkeys employ different tools and techniques will allow us to better understand the pressures that may have shaped the evolution of those behaviors in primates.

Mother of all bonds: Influences on spatial association across the lifespan in capuchins.

In humans, being more socially integrated is associated with better physical and mental health and/or with lower mortality. This link between sociality and health may have ancient roots: sociality also predicts survival or reproduction in other mammals, such as rats, dolphins, and non-human primates. A key question, therefore, is which factors influence the degree of sociality over the life course. Longitudinal data can provide valuable insight into how environmental variability drives individual differences in sociality and associated outcomes. The first year of life-when long-lived mammals are the most reliant on others for nourishment and protection-is likely to play an important role in how individuals learn to integrate into groups. Using behavioral, demographic, and pedigree information on 376 wild capuchin monkeys (Cebus imitator) across 20 years, we address how changes in group composition influence spatial association. We further try to determine the extent to which early maternal social environments have downstream effects on sociality across the juvenile and (sub)adult stages. We find a positive effect of early maternal spatial association, where female infants whose mothers spent more time around others also later spent more time around others as juveniles and subadults. Our results also highlight the importance of kin availability and other aspects of group composition (e.g., group size) in dynamically influencing spatial association across developmental stages. We bring attention to the importance of-and difficulty in-determining the social versus genetic influences that parents have on offspring phenotypes. RESEARCH HIGHLIGHTS: Having more maternal kin (mother and siblings) is associated with spending more time near others across developmental stages in both male and female capuchins. Having more offspring as a subadult or adult female is additionally associated with spending more time near others. A mother's average sociality (time near others) is predictive of how social her daughters (but not sons) become as juveniles and subadults (a between-mother effect). Additional variation within sibling sets in this same maternal phenotype is not predictive of how social they become later relative to each other (no within-mother effect).

Assessing morphological preservation of gastrointestinal parasites from fecal samples of wild capuchin monkeys (Cebus imitator) stored in ethanol versus formalin

The copromicroscopic identification of gastrointestinal parasites is a common, cost-effective method vital to understanding host-parasite interactions. However, its efficacy depends on effective preservation of the samples. In this study, we compare the preservation of ethanol and formalin preserved gastrointestinal parasites collected from a wild population of Costa Rican capuchin monkeys (Cebus imitator). Fecal samples were collected, halved, and stored in either 10% formalin or 96% ethanol at ambient temperature, then microscopically screened for the presence of parasites. Parasites were morphologically identified and rated based on their preservation using a newly developed rubric. We identified more parasitic morphotypes in formalin-preserved samples but found no difference in the number of parasites per fecal gram (PFG) between mediums. There was no difference in the PFG of two most prevalent parasite morphotypes, Filariopsis barretoi larvae and Strongyle-type eggs, and while Filariopsis larvae were better preserved in formalin, strongyle eggs showed no preservation difference between mediums. Our results support the suitability of both ethanol and formalin for morphological parasite identification in samples stored over 1 year, describe the morphological changes and challenges associated with parasite degradation, and highlight the potential for future studies to use both morphological and molecular methods in non-invasively collected samples.

Mapping nut-cracking in a new population of wild capuchin monkeys (Sapajus libidinosus) at Ubajara National Park, Brazil.

Populations of bearded capuchin monkeys (Sapajus libidinosus) vary in their tool use behaviors, with some of this divergence regarded as culturally determined. The use of stone tools, primarily to crack open encased foods, is widespread among bearded capuchins living in dry habitats (Caatinga and Cerrado). Significant diversity in targets, processed foods, material, and size of tools is observed across populations. However, so far, only a few sites have been systematically studied, and we are still distant from a representative picture of the range of variation in capuchins' culture. In this study, we did a systematic assessment of stone tool use sites in the Ubajara National Park (UNP), in the Caatinga region of Ceará, Brazil, recording and measuring stone tools, processed foods, and available lithic resources as part of an extensive comparative research, the CapCult project. We found indirect and direct evidence that capuchin monkeys at UNP customarily use hammerstones and anvils to process at least two species of palm nuts, macauba (Acrocomia aculeata) and the harder babaçu (Attalea speciosa). Most of the anvils were rock surfaces and had leftovers of only one palm nut species. The hammerstones used to process both palm nuts were not significantly different in weight, although the ones used for Ac. aculeata were longer. We found a higher frequency of nut-cracking sites in the drier lowland area of the park, reflecting differences in the density of the most common palm species, Ac. aculeata, and availability of raw stone material. The stone tool use observed in UNP is within the scope of previously reported in savannah capuchin populations. Our study widens the knowledge of stone tool-use diversity in wild capuchin monkeys, which could contribute to shaping conservation policy, including cultural traits.

Guidelines and considerations for capturing and collaring wild primates: a case study with capuchin monkeys (Sapajus nigritus cucullatus).

Many aspects of the ecology, evolution and social behavior of wild-living primates remain un-explored and require further investigation. While long-term field studies are crucial for addressing conservation concerns for many primates' species, acquiring the necessary data is often challenging, often due to difficulties in locating study groups. Radio-telemetry has significantly facilitated the study of primates and other animals living in tropical forests. However, there are important practical challenges in the process of capturing and releasing animals after placement of telemetry collars. In this study, we report guidelines and considerations for capturing and collaring wild capuchin monkeys, Sapajus nigritus cucullatus, in the Atlantic Forest of Argentina. Our ultimate goal is to contribute to making captures safer, preventing harm and stress to animals when using radio-telemetry in monitoring strategies for conservation of this primate species. These methods can be useful for researchers using field capture and radio-telemetry for monitoring groups or populations of wild primates, specifically wild Sapajus.

Tourist Knowledge of and Beliefs about Wild Capuchin Monkeys (Sapajus nigritus) at Iguazú National Park, Argentina

Tourist Knowledge of and Beliefs about Wild Capuchin Monkeys (Sapajus nigritus) at Iguazú National Park, Argentina

Activity budget and gut microbiota stability and flexibility across reproductive states in wild capuchin monkeys in a seasonal tropical dry forest

BackgroundEnergy demands associated with pregnancy and lactation are significant forces in mammalian evolution. To mitigate increased energy costs associated with reproduction, female mammals have evolved behavioural and physiological responses. Some species alter activity to conserve energy during pregnancy and lactation, while others experience changes in metabolism and fat deposition. Restructuring of gut microbiota with shifting reproductive states may also help females increase the energy gained from foods, especially during pregnancy. The goal of this study was to examine the relationships among behaviour, gut microbiota composition, and reproductive state in a wild, non-human primate to better understand reproductive ecology. We combined life history data with > 13,000 behavioural scans and 298 fecal samples collected longitudinally across multiple years from 33 white-faced capuchin monkey (Cebus imitator) females. We sequenced the V4 region of the 16S rRNA gene and used the DADA2 pipeline to analyze microbial diversity. We used PICRUSt2 to assess putative functions.ResultsReproductive state explained some variation in activity, but overall resting behaviours were relatively stable across pregnancy and lactation. Foraging was less frequent among females in the early stage of nursing compared to the cycling stage, though otherwise remained at comparable levels. Maximum temperature was a strong, significantly positive predictor of resting, while social dominance had a small but significantly negative effect on resting. Ecological variables such as available fruit biomass and rainfall had a small but significantly positive effects on measures of foraging time. Gut microbial community structure, including richness, alpha diversity, and beta diversity remained stable across the reproductive cycle. In pairwise comparisons, pregnant females exhibited increased relative abundances of multiple microbial ASVs, suggesting small changes in relation to reproductive state. Reproductive state was not linked to differential abundance of putative metabolic pathways.ConclusionsPrevious data suggest that activity budget and the gut microbiome shifts considerably during reproduction. The present study finds that both activity and gut microbial communities are less associated with reproduction compared to other predictors, including ecological contexts. This suggests that behavioural flexibility and gut microbial community plasticity is contrained by ecological factors in this population. These data contribute to a broader understanding of plasticity and stability in response to physiological shifts associated with mammalian reproduction.

Promise and limitations of 18S genetic screening of extracted fecal DNA from wild capuchins

Genomic screening of fecal DNA provides insight into diet, parasite infection dynamics, and other aspects of the ecology and pathogens of wild populations. Here, we amplify and sequence the V4/V5 regions of the eukaryotic 18S ribosomal RNA gene from fecal DNA of wild capuchin monkeys (Cebus imitator). We collected 94 fecal samples from 26 individuals, each sampled 1-4 times across a 19-month period and examined the eukaryotic diversity in 63 of these samples which had sufficient numbers and quality of reads during downstream analyses. We found a total of 234 distinct amplicon sequence variants (ASVs) classified as Eukaryotes in our samples. Of these, 66 were assigned to the phylum Nematoda. 64 ASVs are from taxa that possibly parasitize monkeys or their food items: 33 were assigned to lungworms (Superfamily Metastrongyloidae; genus Angiostrongylus), two to the genus Strongyloides, and one to the genus Austrostrongylus. The remaining 28 ASVs were assigned to nematodes that likely parasitize plants and/or invertebrates that the monkeys consume. Taken together with past dietary and coprological study of the same primate population, our results suggest that invertebrate consumption and parasitic infection, especially by lungworms, is common and widespread among this population of wild monkeys. We also discuss limitations of our approach, including the amplification of off-target ASVs, and make suggestions for future research. Overall, 18S screening shows promise for identifying various components of the capuchin gastrointestinal eukaryotic ecosystem, including parasitic helminths, and its utility will increase with the improvement of genetic databases.

Linking primatology and archaeology: The transversality of stone percussive behaviors

Since the launch of the Journal of Human Evolution fifty years ago, the archaeology of human origins and the evolution of culture have witnessed major breakthroughs with the identification of several new archaeological sites whose chronology has been slowly pushed back until the discovery of the earliest evidence of stone tool making at Lomekwi 3 (West Turkana, Kenya), at 3.3 Ma. Parallel to these discoveries, the study of wild primates, especially chimpanzees (Pan troglodytes), allowed the development of models to understand key aspects of the behavior of extinct hominin species. Indeed, chimpanzees possess an impressive diversity of tool-aided foraging behaviors, demonstrating that technology (and culture) is not exclusive to humans. Additionally, current research has also shown that wild capuchin monkeys (Sapajus libidinosus) and long-tailed macaques (Macaca fascicularis) also rely on stone percussive foraging behaviors. The investigation of these primates is boosting new interpretative models to understand the origins of stone flaking and the archaeological signature left by these primates. This review aims to present an examination of the state-of-the-art and the current advances made in the study of the earliest hominin technology and primate percussive behaviors. Overall, we argue that while it has been shown that extant primates can generate unintentional flakes, early hominins exhibited skills in the production and use of flakes not identified in primates. Nonetheless, we stand up to continue developing interdisciplinary approaches (i.e., primate archaeology) to study extant primates, as these endeavors are essential to move forward toward a detailed understanding of the technological foraging behaviors beyond the genus Homo. Finally, we discuss future challenges for the study of the emergence of stone technology.

Greater tool use diversity is associated with increased terrestriality in wild capuchin monkeys.

Our goals were to (1) measure the terrestriality levels of a group of capuchin monkeys and (2) test the hypothesis that terrestriality has a positive effect on the stone tool use variability because the increased time on the ground would offer more opportunities to interact with the available stones, leading to more innovations of tool use behaviors. We predict a more diversified use of stone tools in the population with a higher degree of terrestriality. This study was on a group of capuchin monkeys (Sapajus libidinosus) at Serra da Capivara National Park (SCNP), Brazil. Scan sampling was done for 23 months, recording the behavior and substrate used by the individuals. The ground use rate was 41%, with no sex difference but an age difference: infants were less terrestrial than juveniles and adults. Compared to a population with a more limited tool use repertoire (Fazenda Boa Vista), SCNP adult capuchins are more terrestrial (43% v. 27%). Stone tool use diversity and terrestriality in capuchins appear to be positively correlated. Our results support this hypothesis and provide terrestriality measurements of the wild capuchin population with the most complex stone tool kit.

Experimental evidence of parasite-induced behavioural alterations modulated by food availability in wild capuchin monkeys

In disease dynamics, host behaviour can both determine the quantity of parasites a host is exposed to, and be a consequence of infection. Observational and experimental studies in non-human primates have consistently found that parasitic infections result in less movement and reduced foraging, which was interpreted as an adaptive response of the host to counter infection. Variation in host nutritional condition may add complexity to the infection-behaviour relationship, and its influence may shed light on its significance. To experimentally evaluate how host activity and social relationships are affected by the interaction of parasitism and nutrition, during two years we manipulated food availability by provisioning bananas, and helminth infections by applying antiparasitic drugs, in two groups of wild black capuchin monkeys (Sapajus nigritus) in Iguazú National Park, Argentina. We collected faecal samples to determine the intensity of helminthic infections, as well as data on behaviour and social proximity. Individuals with unmanipulated helminth burdens foraged less than dewormed individuals only when food provisioning was low. Resting time was increased when capuchins were highly provisioned, but it did not vary according to the antiparasitic treatment. Proximity associations to other group members were not affected by the antiparasitic treatment. This is the first experimental evidence of a modulating effect of food availability on the influence of helminth infection on activity in wild primates. The findings are more consistent with an impact on host behaviour due to the debilitating effect caused by parasites than with an adaptive response to help fight infections.

Animal behavior: Monkeys use tools for diet quality, not quantity

An enduring question in the study of human evolution is why tool use evolved. A new study has found that stone tools improve diet quality in wild capuchin monkeys. Tools may have similarly increased the nutritional security in ancestral hominins.

A primate model for the origin of flake technology

When and how human ancestors first used tools remains unknown, despite intense research into the origins of technology. It has been hypothesized that the evolutionary roots of stone flake technology has its origin in percussive behavior. Before intentional stone flaking, hominins potentially engaged in various percussive behaviors resulting in accidental flake detachments. We refer to this scenario as the ‘by-product hypothesis.’ In this scenario, repeated detachments of sharp stone fragments eventually resulted in intentional flake production. Here, we tested the circumstances of accidental flake production as a by-product of percussive foraging in wild capuchin monkeys (Sapajus libidinosus) from Brazil, the only nonhuman primate known to habitually produce sharp-edged flakes through a percussive behavior. We conducted field experiments where we tested the potential for accidental flake production during nut cracking. We provided three different types of stone with varied material properties as anvils to assess the circumstances in which accidental production of sharp-edged flakes occurs during nut cracking. A further freehand knapping experiment, with the raw material that exhibited accidental flake detachments, allows a direct comparison of flakes that have been intentionally produced by an experienced knapper and flakes produced during nut cracking by capuchin monkeys. Our results show that raw material quality and morphology significantly affect the rate of sharp-edged flake production as well as the resulting lithic signature of this behavior. In addition, accidental flakes produced during capuchin nut cracking on highly isotropic raw material are similar in many respects to intentionally produced flakes by a human knapper. Our field experiments highlight the fact that nut-cracking behavior can lead to the unintentional production of substantial quantities of sharp-edged flakes and therefore supports the ‘by-product hypothesis’ as a potential mechanism for the emergence of hominin flake technology.

Stone tools improve diet quality in wild monkeys

Tool use is a fundamental feature of human evolution. Stone tools are in the archaeological record from 3.4 Ma, even before Homo,1 and the use of stone tools probably predated the split between hominins and panins.2 Using tools (hereafter, tooling cf Fragaszy and Mangalam3) is hypothesized to have improved hominins' foraging efficiency or access to high-quality foods.4-7 This hypothesis is supported if feeding with tools positively contributes to diet quality in extant non-human primates or if foraging efficiency is increased by tooling. However, the contribution of tooling to non-human primates' foraging success has never been investigated through a direct analysis of nutritional ecology.8,9 We used multi-dimensional nutritional geometry to analyze energy and macronutrients (nonstructural carbohydrates, lipids, and protein) in the diets of wild capuchin monkeys (Sapajus libidinous) that routinely crack palm nuts with stone hammers.10,11 We show that eating nuts obtained through tooling helps monkeys to achieve more consistent dietary intakes. Tooling increased the net energy gain by 50% and decreased the proportion of fiber ingested by 7%. Tooling also increased the daily non-protein energy intake. By contrast, protein intake remained constant across foraging days, suggesting a pattern of macronutrient regulation called protein prioritization, which is also found in contemporary humans.8,9 In addition, tooling reduced dispersion in the ratio of protein to non-protein energy, suggesting a role in macronutrient balancing. Our findings suggest that tooling prior to tool making could have substantially increased the nutritional security of ancestral hominins, sowing the seeds for cultural development.5,7 VIDEO ABSTRACT.

Vertebrate Predation and Tool-Aided Capture of Prey by Savannah Wild Capuchin Monkeys (Sapajus libidinosus)

Vertebrate predation was a vital behavior during human evolution. Some Afro-Eurasian primates, such as baboons (Papio spp.) and chimpanzees (Pan troglodytes), frequently hunt and consume vertebrate prey. Capuchin monkeys (Cebus and Sapajus) are omnivorous platyrrhines, and also hunt and consume vertebrates opportunistically. Bearded capuchin monkeys (Sapajus libidinosus) living in semi-arid savannah environments use stone tools to obtain food resources. However, only one population at Serra da Capivara National Park, Brazil, is known to use stick probes to enhance predation. I present data collected for 2 years on vertebrate predation and consumption by two groups of capuchins in this population. Recording vertebrate predation events ad libitum, I observed 72 events, at a rate of 4.6 events/100 h. The most frequent prey were lizards and snakes, followed by birds and rodents, including larger rodents such as adult rock cavies (Kerodon rupestris). The monkeys also preyed on bats, albeit rarely. Predation on vertebrates, including prey that are large relative to their body size, use of tools to aid predation, and a high degree of terrestriality in the savannah environment make robust capuchins a suitable model to understand human evolution, as well as a good comparison with Afro-Eurasian primate models.

Validating Urinary Neopterin as a Biomarker of Immune Response in Captive and Wild Capuchin Monkeys.

Non-invasive health monitoring is advantageous for wild and captive primate populations because it reduces the need for traditional invasive techniques (i.e., anesthetization) that can be stressful and potentially harmful for individuals. The biomarker neopterin is an emerging tool in primatology to measure immune activation and immunosenescence, however, most neopterin studies have focused on catarrhine species with little comparative work examining neopterin and health in platyrrhines. To address this gap, we validated a commercially available enzyme-linked immunosorbent assay (ELISA) to measure urinary neopterin in two types of capuchin monkeys, a wild population of white-faced capuchins (Cebus imitator) and a socially housed captive colony of tufted capuchins (Sapajus apella). We analytically validated methods for measuring urinary neopterin in two capuchin populations and demonstrated that two commonly-used methods to control for urine concentration—creatinine and specific gravity (SG)—produced highly concordant results. We also biologically validated these methods by examining variation in neopterin levels based on environment (captive and wild) and age, and changes in levels associated with immune-response. We found that neopterin increased after immune perturbation (rabies vaccine booster), varied by environmental condition, and mirrored expected trends in immune system ontogeny. Our results improve understanding of the innate immune system in platyrrhine species and suggest neopterin may be useful for non-invasive health monitoring in both captive and wild primates.

Sharing spaces: niche differentiation in diet and substrate use among wild capuchin monkeys

Understanding variation in social grouping patterns among animal taxa is an enduring goal of ethologists, who seek to evaluate the selective pressures shaping the evolution of sociality. Cohesive association with conspecifics increases intragroup feeding competition and may impose constraints on group size. Furthermore, in sexually dimorphic species, males and females may have different nutritional requirements, which can lead to suboptimal foraging in mixed-sex groups. How do animals living in permanent social groups mitigate these foraging costs? Niche differentiation is often hypothesized as a mechanism, but rigorous and detailed tests of the extent and context of differences in diet and habitat use, key tenets of this hypothesis, are rare. We investigated the potential for niche differentiation in foraging activity budget and environment use in a population of wild white-faced capuchin monkeys, Cebus imitator , in northwestern Costa Rica. Using a robust data set of 15 879 foraging scan samples collected from four groups over 13 months, we found that smaller individuals – e.g. juveniles and females – forage more often on smaller branches. We additionally found clear evidence of predator-sensitive foraging wherein the smallest individuals spent less time on the ground during invertebrate foraging. Importantly, niche differentiation was far more evident overall during invertebrate foraging, likely due to spatial constraints and environmental homogeneity imposed by fruit patches. In summary, we found considerable variation in habitat use across age and sex classes, likely attributable to differences in size and relative predation risk. These variables likely reduce intraspecific feeding competition by promoting differential diet and habitat use. Our results also provide insight into the limits of niche differentiation as a strategy for competition reduction and may shed light on the evolution of fission–fusion dynamics in highly frugivorous species. • Niche differentiation was apparent during invertebrate, but not fruit, foraging. • Use of the forest strata was consistent with predator-sensitive foraging. • Foraging time on difficult-to-access foods did not differ for juveniles and adults. • Smaller individuals – juveniles and females – used smaller substrates more often. • Support substrates affected microhabitat differentiation but are often overlooked.

Testing the niche differentiation hypothesis in wild capuchin monkeys with polymorphic color vision

Abstract The polymorphic color vision system present in most North, Central, and South American monkeys is a textbook case of balancing selection, yet the mechanism behind it remains poorly understood. Previous work has established task-specific foraging advantages to different color vision phenotypes: dichromats (red-green colorblind) are more efficient foraging for invertebrates, while trichromats (color “normal” relative to humans) are more efficient foraging for “reddish” ripe fruit, suggesting that niche differentiation may underlie the maintenance of color vision variation. We explore a prediction of the niche differentiation hypothesis by asking whether dichromatic and trichromatic capuchin monkeys (Cebus imitator) diverge in their foraging activity budget, specifically testing whether dichromats forage more frequently for invertebrates and trichromats forage more frequently for “reddish” ripe fruit. To assess this, we analyze a large data set of behavioral scan samples (n = 21 984) from 48 wild adult female capuchins of known color vision genotype, dominance rank, and reproductive status, together with models of food conspicuity. We find no significant differences between dichromats and trichromats in the frequency of scans spent foraging for different food types but do find that nursing females forage less overall than cycling females. Our results suggest that the potential for color-vision-based niche differentiation in foraging time may be curtailed by the energetic requirements of reproduction, behavioral synchrony caused by group living, and/or individual preferences. While niche differentiation in activity budgets by color vision type is not apparent, fine-scale niche differentiation may be occurring. This research enhances our understanding of the evolutionary processes maintaining sensory polymorphisms.

Anticipating future actions: Motor planning improves with age in wild bearded capuchin monkeys (Sapajus libidinosus).

Self-directed object manipulation tasks illuminate development of motor planning. Grasping strategies that lead to good object control to perform the following action(s) reveal second-order motor planning. Motor planning for efficient grips develops slowly in children. Age-related differences in other primates have been poorly investigated. Here, we investigated anticipatory motor planning of infant, juvenile and adult wild capuchin monkeys grasping a horizontally positioned stick baited to the left or right side (a version of the elevated spoon task). We recorded the grasps capuchins used to bring the baited end of the stick to the mouth. The percentage of efficient radial grips positively correlated with age and adults used efficient grips significantly more frequently than infants. Adult wild capuchins' use of radial grips was higher than that reported for adult captive capuchins in similar tasks, suggesting that experience throughout life may influence motor anticipation. Self-directed object manipulation tasks will be useful to compare this aspect of cognition across primates. A video abstract of this article can be viewed at https://youtu.be/a1Zbr_AQkb8.