Urine Washing and Sniffing in Wild White-faced Capuchins (<Emphasis Type="Italic">Cebus capucinus</Emphasis>): Testing Functional Hypotheses

Urine washing (UW) is taxonomically widespread among strepsirhines and platyrrhines, yet its functional significance is still unclear. We used 2274 h of focal follows of 35 adult and subadult wild white-faced capuchins (Cebus capucinus) to test 1) the intergroup signaling, intragroup social signaling, and thermoregulatory hypotheses for UW and 2) the hypothesis that individuals sniff each other's urine and other traces to gather socially significant information. Males engaged in significantly more UW than females. All 5 α-males engaged in more UW than subordinate males did, including 4 α-males that increased their UW rate above that of their male groupmates after their rise to α rank. Males engaged in significantly less UW while in view of other males than at other times. Male-male sniffing rates do not correlate with either aggression rate or dominance rank distance. Urine washing rates did not increase while subjects were in parts of their home range where more intergroup encounters occurred. Urine washing rates were highest early in the morning and late in the afternoon, presumably when temperatures were coolest. The data do not support either the thermoregulatory or social signaling hypothesis. We suggest that experiments with captive capuchins are necessary to resolve the issue of the function of urine washing in the taxon.     

Behavioral adaptations to heat stress and water scarcity in white-faced capuchins (Cebus capucinus) in Santa Rosa National Park, Costa Rica

We examined thermoregulatory behaviors in a wild population of white-faced capuchins (Cebus capucinus) inhabiting a highly seasonal dry forest in Santa Rosa National Park (SRNP), Costa Rica. The dry season in SRNP lasts approximately 5 months and is characterized by high ambient temperatures regularly exceeding 37 degrees C, low relative humidity, and the near absence of precipitation. This study demonstrates that capuchins rest more and travel shorter distances during the hottest and driest hours of the day, and suggests that they extend their tongues to lower body temperature via evaporative cooling. Seasonal weather patterns and group movement data reported here are based on 940 h of observations on three social groups of capuchins (wet season: 370 h, dry season: 570 h). In the dry season, the proportion of time spent resting increased at higher temperatures whereas the proportion of time spent traveling decreased. Distance traveled between location points taken at half-hour intervals decreased significantly as temperature increased, although the correlation was not strong. Capuchins exposed their tongues during hot, dry, windy conditions, and this behavior was much more frequent in the dry season. Temperature was significantly higher and humidity significantly lower for "tongue-out" events than expected for a random event in the dry season. Finally, as surface water became scarce, home-range areas of heavy use became increasingly centered on the remaining permanent water sources. These results suggest that heat stress and water scarcity are significant influences on the behavior of capuchins in hot, dry conditions.     

Why do capuchin monkeys urine wash? An experimental test of the sexual communication hypothesis using fMRI

Urine washing (UW) consists of depositing urine on the hands and vigorously rubbing the body. As urine contains chemical and pheromonal cues, UW may convey socially relevant information. Although ritualized UW is observed in many New World primates, including capuchin monkeys, the functional significance of UW remains unclear. In this experiment, we investigated the social signaling hypothesis of UW. Specifically, we hypothesized that UW by males conveys socially relevant signals that females can detect. We used functional magnetic resonance imaging (fMRI) to test whether adult female capuchins show differential brain activation in response to adult male and juvenile male capuchin urine. We expected to see changes in activation of structures involved in olfactory processing, including the piriform cortex, medial preoptic and anterior hypothesis, orbitofrontal cortex, hippocampus, and cerebellum. Data were acquired from four adult female capuchin monkeys. Presentations of odor stimuli (obtained from unfamiliar males) were made during fMRI acquisition using a standard ON-OFF design. All fMRI data were spatially normalized to a template and analyzed using the FMRI Expert Analysis Tool Version 5.98, part of the FMRIB's Software Library (www.fmrib.ox.ac.uk/fsl). Whole brain analyses revealed significant activations in the inferior temporal cortex, parahippocampal gyrus, precuneus, hippocampus, pulvinar, and cerebellum when females were presented with the adult male urine. Notably, significantly greater signal activation was observed in several regions associated with olfactory processing, when subjects were presented with adult male urine as compared with urine from juvenile males. Our results indicate that UW serves a social communicative function in capuchins, providing support for the sexual signaling hypothesis.     

Development of an 82.2 degrees C (180 degrees F) temperature indicatior system for monitoring equipment washing and sanitizing programs

A survey performed at 12 institutions showed that while the temperatures in the water tanks of mechanical cage washers were monitored, these temperatures deviated from the temperatures obtained on the items actually being washed. Most surveyed facilities were not meeting the 82.2 degrees C (180 degrees F) standard in the washing chamber. A temperature indicator was developed which revealed whether 82.2 degrees C had been reached at the surface of the items being sanitized. The indicator was a sealed glass ampule which produced a visible color change when exposed to temperatures of 82.2 degress C or higher. The indicator was located on the items being washed. Due to the variability of water heating in washing machines, it was recommended that one indicator be used in each load of equipment being sanitized.     

Investigations on isolated islets of Langerhans in vitro. Influence of temperature changes during preparation on some parameters of insulin metabolism.

Pancreatic islets of Wistar rats were prepared by digestion with collagenase and then washed and isolated at three different temperatures (4, 22 and 37 degrees C). The efficiency of washing with regard to proteolytic and collagenolytic activities in the wash buffer was not affected by the temperatures used. The islet thiol:protein-disulphide oxidoreductase activity (EC 1.8.4.2) was apparently unchanged, whereas washing temperatures lower than 37 degrees C resulted in a diminished insulin content. The insulin secretion of islets, isolated at 4 degrees C, is reduced in response to glucose without changing the sigmoidal shape of dose-response curve.     

Chemical communication in Cavia: Responses of wild (C. aperea), domestic (C. porcellus) and F1 males to urine

Urine preferences of wild (Cavia aperea), domestic (C. porcellus), and F₁ adult male guinea pigs were investigated. Males of all three types preferred female urine to male urine regardless of donor type. When given a choice between female urine of each type, males preferred conspecific urine. In choices between male urine of the three types, a conspecific preference was evident for wild and domestic but not f₁ subjects. These data indicate that a loss of distinctive male and female odours has not occurred as a result of domestication. However, the urine odours of wild and domestic types have diverged. The possible effects of previous individual experience on the preferential response is discussed.     

Reproductive Socioecology of Tufted Capuchins (Cebus apella nigritus) in Northeastern Argentina

We describe the reproductive parameters of tufted capuchins (Cebus apella nigritus) in the Iguazú National Park, NE Argentina. We obtained data on six different groups (33 individually recognized adult females) studied for periods of 2–9 years. Estimated birthrate is 0.59 infants per female per year in unprovisioned groups. A group that was provisioned for 6 years during the winter period of low fruit availability (May–August), showed a similar birth rate of 0.61, but a lower infant mortality rate than unprovisioned groups. The birthrate estimated for this population is higher than the one reported for white-faced and wedge-capped capuchins. The mean interbirth interval is 19.35 months, but a female can have infants in successive years, even when her previous infant has survived. The modal age at first delivery is 7 years, which is similar to the one observed in wedge-capped capuchins. When young adult females come into estrous they avoid copulating with the alpha male that sired them, thus providing evidence for a behavioral mechanism of inbreeding avoidance. Births are very seasonal at Iguazú, occurring during the spring and summer months (October–February) when food availability is at its peak. Tufted capuchins at Iguazú are more seasonal breeders than other capuchin populations, probably as a result of their more seasonal environment. The secondary sex ratio does not deviate significantly from 1:1, despite the known ability of capuchins to adjust secondary sex ratio to local conditions.     

Testing for Links Between Female Urine Odor and Male Sexual Behaviors in Japanese Macaques (<Emphasis Type="Italic">Macaca fuscata</Emphasis>)

Urine is involved in sexual communication in New World monkeys and lemurs, but most studies of the role of olfaction in sexual communication in Old World monkeys have focused on vaginal secretions rather than urine. We investigated whether female urine promotes male sexual behaviors (approaches and inspections of genital area) in Japanese macaques (Macaca fuscata). We used a sequential presentation paradigm in behavioral experiments, presenting unfamiliar female urine and control cotton swabs to males living in a social group with cycling females. We tested whether males (N = 3) showed more processing behaviors (licking, sniffing, tasting) toward female urine (22 stimuli per male from prefertile, fertile, and postfertile phases, based on urinary estrone and progesterone conjugate profiles) than control odor (8 stimuli per male). We then compared male sexual behaviors toward resident females pre- and post-exposure to stimuli and in relation to the females’ reproductive status (perifertile, nonfertile, and pregnancy periods, based on fecal estrone and progesterone conjugate profiles). We found that males showed significantly more processing behaviors toward urine stimuli than to controls but that male behavior did not vary across urine samples from prefertile, fertile, and postfertile phases. Exposure to unfamiliar female urine stimuli did not modulate male approaches to and inspections of resident females at any stage of the female reproductive cycle. Although our study is limited by its small sample size, the results suggest that female urine contains compounds that males detect, but we found no evidence that female urine is related to male sexual behaviors.     

Predictors of Parasitism in Wild White-Faced Capuchins (Cebus capucinus)

Parasite infections in wildlife are influenced by many factors including host demography, behavior and physiology, climate, habitat characteristics, and parasite biology and ecology. White-faced capuchins (Cebus capucinus) host a suite of gastrointestinal and pulmonary parasites, yet the mechanisms affecting host susceptibility and parasite transmissibility have not been examined in this host species. We used the information-theoretic approach (Akaike’s information criterion) and traditional null-hypothesis testing to determine which host characteristics, behaviors, or environmental factors affected the presence of two prevalent capuchin parasites (Filariopsis barretoi and Strongyloides sp.) as well as parasite species richness in four groups of wild capuchins from September 2007 to January 2008 and January to August 2009. Older capuchins were more likely to be infected with Filariopsis barretoi and had higher parasite species richness. Age-biased nematode infections may stem from age differences in capuchin behavior and physiology while high species richness likely results from long- term exposure to numerous parasite species. Infections with Strongyloides sp. were more likely to occur in the dry season when capuchins often descend to the forest floor to drink from terrestrial water sources, potentially increasing their risk of infection from soil-borne larvae. Capuchin behaviors were poor predictors of parasitism, as were female rank, host sex, home range size, and habitat quality. Many of our results were atypical for primate parasitology, suggesting that host–parasite interactions, and subsequently infection risk, may differ in highly seasonal habitats such as tropical dry forests where these monkeys occur.     

Survival of Microorganisms in Laundered Polyester-Cotton Sheeting

The effects of wash-water temperature, cold-water or regular detergent, wash-cycle design, drying, and drying temperature on survival of four microorganisms on polyester-cotton sheeting were examined. Escherichia coli T3 bacteriophage survived washing at 24, 35, 46, and 57 C, but not at 68 C. Serratia marcescens survived only the lowest three wash temperatures. Levels of residual Staphylococcus aureus were diminished at the highest two wash temperatures, but survival was substantial even at 68 C. Counts of Bacillus stearothermophilus spores were not altered appreciably by wash temperature. Type of detergent had no practical effect on observed counts. The regular wash cycle was significantly more efficient in removal of microorganisms than the permanent-press cycle. Counts, especially of the bacteriophage and the gramnegative bacterium, were decreased by drying; after drying, the effects of wash-water temperature on S. aureus and B. stearothermophilus were not significantly different. Microorganisms were transferred from inoculated to sterilized sheeting during laundering. The public health significance of these observations is discussed.     

Social Aspects of Fur-rubbing in <Emphasis Type="Italic">Cebus capucinus</Emphasis> and <Emphasis Type="Italic">C. apella</Emphasis>

Capuchins rub particular plant materials into their pelage, a behavior for which most authors have proposed a medicinal function (Baker in American Journal of Primatology 38:263–270, 1996, Baker, M. (1998). Fur Rubbing as Evidence for Medicinal Plant Use by Capuchin Monkeys (Cebus capucinus): Ecological, Social, and Cognitive Aspects of the Behavior. Dissertation thesis. University of California Riverside; DeJoseph et al. in Journal of the American Academy of Dermatology 46:924–925, 2002). Individuals fur-rub solitarily or in groups, but researchers have not conducted studies to understand the differences. We investigated the link between the form of fur-rubbing and other social variables in 2 capuchin species. We supplied 2 captive groups —white-faced capuchins and tufted capuchins— with citrus fruit and onions and explored the behavioral processes and social aspects underlying the activity. We documented the occurrence, number of participants, and effect of recruitment behaviors in fur-rubbing subgroups. We investigated the role of kinship, affiliation, and dominance relationships in accounting for fur-rubbing groups. There is a significant difference in the form of fur-rubbing between white-faced and tufted capuchins. White-faced capuchins fur-rubbed mainly in subgroups and performed a particular behavior to recruit prospective participants, whereas tufted capuchins fur-rubbed mainly alone, and showed no particular motivation to be joined by other group members. White-faced capuchins could fur-rub together frequently, whatever their degree of kinship, affiliation, or dominance interval. In tufted capuchins, fur-rubbing appeared to be significantly affected by kinship and dominance.     

Olfactory discrimination of urine odors from five species by tufted capuchin (Cebus apella)

Urine collected from New World monkeys (tufted capuchin, squirrel monkey, cotton-top tamarin) and Old World monkeys (rhesus macaque, Japanese macaque), was used as the odor stimuli. Two adult tufted capuchins were trained on a successive odor-discrimination task with two odors, 30 trials each, in one session per day. Responses to one of the two odors (S+) were reinforced by sweet water. The monkeys failed to discriminate between the urine from the two species of macaques but could discriminate among the urine from the three species of New World monkeys. Furthermore, similarity of urine odors was analyzed by multi-dimensional scaling (MDS) and a cluster analysis. These analysis suggested that the tufted capuchin can distinguish differences among New World monkeys but not between the macaques. The natural distribution of the tufted capuchin overlaps with that of other New World monkeys, but it does not overlap with those of Old World monkeys. Consequently, it can be concluded that this difference in olfactory recognition in the tufted capuchin reflects their sympatric and allopatric relationships with other species.     

Postconflict Behavior of Captive Brown Capuchins in the Presence and Absence of Attractive Food

Most of what we know about postconflict behavior comes from studies on chimpanzees and other Old World semiarboreal and semiterrestrial species. Few studies have investigated whether the context of a fight affects reconciliation—selective postconflict attraction between former opponents—and consolation: selective attraction between conflict participants and other group members. We studied social conflict and its aftermath in two captive groups of brown capuchins (Cebus apella), an arboreal New World species. We observed postconflict behavior in two contexts: (1) during the presence of highly attractive, clumped food—food condition—and (2) in the absence of such food—nonfood condition. Commercial monkey chow was available ad libitum in the nonfood condition. A comparison of postconflict and control observations revealed a conciliatory tendency in the capuchins, but only following fights that occurred in the absence of highly attractive food. Other group members tended not to seek postconflict contact with former conflict participants. However, when shortly after fights recipients of aggression, but not aggressors, initiated affiliation with third parties, the latter not only allowed proximity or contact but also often reciprocated through grooming, play, and especially the exchange of friendly signals. We discuss these results within the framework of current knowledge of postconflict behavior with special emphasis on similarities and differences in the postconflict behavior of Cebus and Pan.     

Inactivation of Ascaris Eggs in Source-Separated Urine and Feces by Ammonia at Ambient Temperatures

Sustainable management of toilet waste must prevent disease transmission but allow reuse of plant nutrients. Inactivation of uterus-derived Ascaris suum eggs was studied in relation to ammonia in source-separated urine without additives and in human feces to which urea had been added, in order to evaluate ammonia-based sanitation for production of safe fertilizers from human excreta. Urine was used concentrated or diluted 1:1 and 1:3 with tap water at 4, 14, 24, and 34°C. Fecal material, with and without ash, was treated with 1% or 2% (wt/wt) urea at 24 and 34°C. At 34°C eggs were inactivated in less than 10 days in urine and in amended feces. At 24°C only feces with 2% (wt/wt) urea or 1% (wt/wt) urea at high pH (10) inactivated all eggs within 1 month, and no inactivation was observed after 75 days in urine diluted 1:3 (18 ± 11 mM NH₃). At temperatures of ≥24°C, NH₃ proved to be an efficient sanitizing agent in urine and feces at concentrations of ≥60 mM. Treating fecal material at 34°C can give a 6-log₁₀ egg inactivation within 1 month, whereas at 24°C 6 months of treatment is necessary for the same level of egg inactivation. At temperatures of 14°C and below, inactivation rates were low, with viable eggs after 6 months even in concentrated urine.     

Jaw-muscle fiber architecture in tufted capuchins favors generating relatively large muscle forces without compromising jaw gape

Tufted capuchins (sensu lato) are renowned for their dietary flexibility and capacity to exploit hard and tough objects. Cebus apella differs from other capuchins in displaying a suite of craniodental features that have been functionally and adaptively linked to their feeding behavior, particularly the generation and dissipation of relatively large jaw forces. We compared fiber architecture of the masseter and temporalis muscles between C. apella (n = 12) and two “untufted” capuchins (C. capucinus, n = 3; C. albifrons, n = 5). These three species share broadly similar diets, but tufted capuchins occasionally exploit mechanically challenging tissues. We tested the hypothesis that tufted capuchins exhibit architectural properties of their jaw muscles that facilitate relatively large forces including relatively greater physiologic cross-sectional areas (PCSA), more pinnate fibers, and lower ratios of mass to tetanic tension (Mass/P₀). Results show some evidence supporting these predictions, as C. apella has relatively greater superficial masseter and temporalis PCSAs, significantly so only for the temporalis following Bonferroni adjustment. Capuchins did not differ in pinnation angle or Mass/P₀. As an architectural trade-off between maximizing muscle force and muscle excursion/contraction velocity, we also tested the hypothesis that C. apella exhibits relatively shorter muscle fibers. Contrary to our prediction, there are no significant differences in relative fiber lengths between tufted and untufted capuchins. Therefore, we attribute the relatively greater PCSAs in tufted capuchins primarily to their larger muscle masses. These findings suggest that relatively large jaw-muscle PCSAs can be added to the suite of masticatory features that have been functionally linked to the exploitation of a more resistant diet by C. apella. By enlarging jaw-muscle mass to increase PCSA, rather than reducing fiber lengths and increasing pinnation, tufted capuchins appear to have increased jaw-muscle and bite forces without markedly compromising muscle excursion and contraction velocity. One performance advantage of this morphology is that it promotes relatively large bite forces at wide jaw gapes, which may be useful for processing large food items along the posterior dentition. We further hypothesize that this morphological pattern may have the ecological benefit of facilitating the dietary diversity seen in tufted capuchins. Lastly, the observed feeding on large objects, coupled with a jaw-muscle architecture that facilitates this behavior, raises concerns about utilizing C. apella as an extant behavioral model for hominins that might have specialized on small objects in their diets.     

Effect of temperature on osmotic and ionic regulation in goldfish,Carassius auratus L.

Summary Urine flow increased with acute temperature increases and showed temperature acclimation. When measured at 20 °C the urine flow of 10 °C acclimated fish was 3.2 times greater than the urine flow of 30 °C acclimated fish. In fish acclimated to 24 °C renal reabsorption of Na and Cl was independent of temperature over an intermediate range of temperatures (14–24 °C) but near the lower lethal temperature (6.5 °C) renal Na and Cl reabsorption was inhibited. Water permeability of the renal tubules was not affected by acute temperature change between 6.5 and 24 °C. Urine osmolality and urine Na, K and Cl concentrations showed nearly perfect temperature compensation in fish acclimated to 10 °C and 30 °C. The rate of renal excretion of Na and Cl showed temperature acclimation in that Na and Cl ecxretion measured at 20 °C was 7 to 8 times greater in 10 °C acclimated fish than in 30 °C acclimated fish. The rate of excretion of Na and Cl measured at 30 °C in 30 °C acclimated fish was approximately 1.7 times the rate of excretion measured at 10 °C in 10 °C acclimated fish.The branchial uptake of Na, measured in tap water, of fish acclimated to 10, 20 and 30 °C in demineralized water increased with acute increases in temperature. When the three acclimation groups were compared at an intermediate temperature (20 °C), the 10 °C acclimated group showed the highest rate of net uptake, and the 30 °C group the lowest rate of uptake. This apparent temperature acclimation of Na uptake was correlated with differences in the plasma Na concentration of the three acclimation groups. Plasma Cl concentrations were also correlated with acclimation temperature in fish acclimated in demineralized water, but the rate of net Cl uptake was considerably less than that for Na. Sodium and Cl uptake in fish which had been acclimated in tap water was very variable and was not clearly affected by acute changes in temperature. Uptake of Na and Cl by fish held in tap water did not show temperature acclimation. The difference between uptake and excretion of fish acclimated in tap water was not significantly different from zero, indicating that the fish were in salt balance.The study was supported by National Institutes of Health Grant GM 16932-02 to Dr. Bodil Schmidt-Nielsen. I am grateful to Dr. Schmidt-Nielsen for many useful discussions during the course of this work.     

The role of soluble cytochrome c-551 in cyclic electron flow-driven active transport in Chromatium vinosum

Spheroplasts have been prepared from the photosynthetic purple sulfur bacterium Chromatium vinosum by lysozyme plus ethylenediaminetetraacetic acid treatment. These spheroplasts are able to take up alanine in the light, but light-dependent alanine uptake is lost upon subsequent washing of the spheroplasts. The observations that alanine uptake driven by a potassium plus valinomycin-induced membrane potential (outside positive) is not affected by washing and that light-dependent alanine uptake can be restored by addition of the supernatant from washing suggest that a soluble electron carrier is lost during washing. Light-dependent alanine uptake in washed spheroplasts could be restored by addition of C. vinosum cytochrome c-551. Other soluble electron carriers from C. vinosum (high-potential iron protein, cytochrome ‘f’, cytochrome c′ and the flavocytochrome c-552) did not restore alanine uptake nor did a variety of other soluble electron carrier proteins from other organisms. These results suggest that cytochrome c-551 functions as an electron carrier in the cyclic electron transfer chain of C. vinosum. Mitochondrial cytochrome c (equine heart) and cytochrome c-551 from Pseudomonas aeruginosa were highly effective in restoring light-dependent alanine uptake in washed spheroplasts, making it likely that C. vinosum cytochrome c-551 is related by evolution to the same cytochrome c family as these other two c cytochromes.     

Temperature-dependent viscoelastic properties of the human supraspinatus tendon

Temperature effects on the viscoelastic properties of the human supraspinatus tendon were investigated using static stress-relaxation experiments and the quasi-linear viscoelastic (QLV) theory. Twelve supraspinatus tendons were randomly assigned to one of two test groups for tensile testing using the following sequence of temperatures: (1) 37, 27, and 17 °C (Group I, n=6), or (2) 42, 32, and 22 °C (Group II, n=6). QLV parameter C was found to increase at elevated temperatures, suggesting greater viscous mechanical behavior at higher temperatures. Elastic parameters A and B showed no significant difference among the six temperatures studied, implying that the viscoelastic stress response of the supraspinatus tendon is not sensitive to temperature over shorter testing durations. Using regression analysis, an exponential relationship between parameter C and test temperature was implemented into QLV theory to model temperature-dependent viscoelastic behavior. This modified approach facilitates the theoretical determination of the viscoelastic behavior of tendons at arbitrary temperatures.     

Why do captive tufted capuchins (Cebus apella) urine wash?

Urine washing (UW) has been observed in numerous species of prosimians and New World monkeys. The functional significance of UW in Cebidae, specifically, Cebus apella, has not been determined. The objective of our study was to test two major hypotheses related to the function of UW: (1) UW functions as a thermoregulatory mechanism, and (2) UW functions as a means of social communication related to (a) territoriality, (b) sexual encounters, or (c) intragroup aggression/agitation. We collected focal data on a captive group of 28 tufted capuchins (C. apella; July-October 2004 and February-July 2005). We found no significant correlation between UW rates and temperature, at a constant, moderate humidity level. Rates of UW were significantly greater outdoors (no conspecific neighbors) vs. indoors (conspecific neighbors). Qualitative evidence suggests a relationship between UW by the alpha male and sexual solicitations from females. UW rates associated with aggression received were significantly higher than UW rates associated with aggression given and UW rates associated with potential fear/stress. There was also a significant negative correlation between cortisol measures and UW frequencies. Our results suggest that UW does not function in thermoregulation or in territorial communication. Alternatively, our results suggest that UW may be associated with sexual encounters and receiving aggression. Additionally, further investigation is warranted to determine whether UW is used as an appeasement mechanism or as a stress reliever or as both.     

Responses to urine odor in the tufted capuchin (Cebus apella)

When the tufted capuchin urinates, it frequently performs “urine-washing”. Previous studies have proposed several hypotheses about this behavior. This study investigated 1) whether the tufted capuchin can distinguish the urine odor of conspecific individuals from other groups, and 2) whether the capuchins can distiguish conspcific urine odor of from that of other species. When an odor bar that had been prepared in conspecific other group's cage was presented, the response (sniffing, licking, or biting) was significantly greater than that to any other odors, including that of the home group, 5 other species, or a neutral odor. This tendency was stronger in males than in females. and suggests that the tufited capuchin is able to discriminate its home group's urine odor from that of the other groups. This monkey may also discriminate its own species from others by urine odor. The sex difference of the response to the odor bar may be the result of differences in social role between males and females. These results support the idea that the tufted capuchin may use olfaction for social communication.