Female baboons do not raise the stakes but they give as good as they get

We used data from four chacma baboon, Papio cynocephalus ursinus, troops, living in two populations, to test the raise the stakes (RTS) strategy of reciprocity. Female baboons did not raise the stakes either within or across grooming bouts. Instead they time-matched grooming contributions and divided grooming into short episodes. In addition, analysis of the grooming behaviour of frequently versus infrequently grooming dyads did not reveal differences in grooming patterns predicted by the RTS strategy. We suggest time constraints preclude the escalation of grooming bout length as required by RTS; the data were more consistent with a strategy of give as good as you get. However, this strategy could not explain all the patterns observed, and we conclude that biological market theory represents a more appropriate framework for investigating female grooming dynamics than dyadic games based on the iterated prisoner's dilemma. We suggest that competitive altruism among individuals acts as a market force influencing an individual's value as a grooming partner. Copyright 2000 The Association for the Study of Animal Behaviour.     

Time-matched grooming in female primates? New analyses from two species

The parcelling model of reciprocity predicts that grooming partners will alternate between giving and receiving grooming within grooming bouts, and that each partner will perform approximately as much grooming as it receives within each bout (‘time matching’). Models of allogrooming based on biological markets theory predict that individuals of lower dominance rank will exchange grooming for tolerance from high-rankers, and therefore an inverse relation will be found between grooming partners' dominance rank distance and how closely they match each other's grooming contributions within each bout. We used weighted logistic regression and weighted least-squares regression to test these predictions using data from female white-faced capuchins, Cebus capucinus, and bonnet macaques, Macaca radiata. Only 5-7% of macaque grooming bouts, and 12-27% of capuchin grooming bouts, were reciprocated. However, (1) the duration of grooming by the first groomer significantly predicted whether the groomee would reciprocate at all, and (2) when bouts were reciprocated, the duration of grooming by the first groomer significantly predicted the duration of grooming by the second groomer. Grooming was most balanced among females of similar dominance ranks. Both the time-matching and rank-related effects were weak, although significant. These results indicate that although some form of time matching may be a general characteristic of grooming in female-bonded primate species, time matching accounts for relatively little of the variation in the distribution of grooming within bouts. We also draw attention to weighted regression as a technique that avoids pseudoreplication while using all available data.     

Signals found in the grooming interactions of wild Japanese monkeys of the koshima troop

Signaling behaviors appearing in grooming interactions of wild Japanese monkeys were analysed. Vocal signals found in the grooming interactions had the content of asking the objective animal “if the vocal signaler may groom the recipient animal.” They could be divided into two categories of vocal sounds, VG-1 and VG-2. The former was uttered in common by all the troop members. The latter was uttered just before grooming by the groomer and is considered to have deeper connection with grooming. Each individual uttered mainly one kind of vocal sound out of VG-2, and the preferred vocal sounds for each individual differed. Furthermore, VG-2 differed in different troops. Behavioral signals had the content of showing “the acceptance of grooming” or showing “the request to be groomed.” The appearance of these signaling behaviors was closely related to the inter-individual relationships of grooming partners, especially as to whether or not they had blood relationships. Basically the monkeys have a system in which they must avoid each other, except in the case of mothers and their offspring, and if they had to approach too closely against this basic system, as in grooming interactions, there appeared signaling behaviors as mentioned above.     

Coping with social tension: Sex differences in the effect of food provision to small rhesus monkey groups

In previous research, male chimpanzees (Pan troglodytes) were found to be more ‘conciliatory’ than females, in that after aggressive incidents males more often engaged in socially positive contact with former opponents. The first part of the present paper presents similar results for a large breeding troop of rhesus monkeys (Macaca mulatta). To investigate further the possible sex difference in postconflict behaviour, a series of experiments was carried out on small isosexual groups of young rhesus monkeys, three male and three female groups. Food competition was created by providing either a single apple piece (Monopoly test) or a handful of small pieces (Equality test). Observations lasted for 30 min, and behaviour in tests without food provisioning was also recorded. The predicted response to food was an increase in aggression followed by restorative behaviour, such as grooming. In Equality tests both sexes showed similar responses, i.e. increased aggression and decreased grooming and cohesiveness. In Monopoly tests, however, their responses differed. After the aggression increase, which occurred in all groups, males showed a significant increase in grooming and cohesiveness, whereas females showed the (non-significant) opposite trend. Another sex difference was that changes in grooming and aggression frequencies were related to the rank order in female groups, but not in male groups. Since there was no evidence for a direct causal connection between grooming and aggression, a new model is introduced which links grooming behaviour to the type of food provision rather than to the social disturbance by aggression. According to this model inequality in food distribution causes social tensions. Males actively try to reduce these tensions, whereas females do not. Some alternative explanations are also discussed.     

Immediate and Delayed Benefits of Play Behaviour: New Evidence from Chimpanzees (Pan troglodytes)

Evidence for the anticipation of competition at feeding time has been previously documented in both Pan species. Chimpanzees seem to cope with competitive tendency through behavioural mechanisms of tension reduction, and grooming is certainly one of these. Social play and grooming are often matched because they bring animals into close physical contact for long periods, and they have an important role in social cohesion. Our goal was to investigate the occurrence of play behaviour during the pre‐feeding period, before a basic maintenance activity is about to take place, in the chimpanzee colony housed in the ZooParc de Beauval (St Aignan sur Cher, France). The group was composed of 10 adults and nine immature individuals. By scan animal sampling (344 h of observation), we recorded play and grooming interactions in all age‐class combinations during four different periods (pre‐feeding, feeding, post‐feeding, control). We found peak levels of grooming interactions among adults during the pre‐feeding time. A peak frequency at the pre‐feeding time was also found in social play between adults and unrelated immature subjects. This finding suggests that during high tension periods, grooming and play might share similar functions in conflict management. Like grooming, play might have an important role to limit aggression and increase tolerance around food (immediate benefits). Immature animals showed a higher frequency of play in the pre‐feeding than in any other condition (feeding, post‐feeding, and control). During high excitement periods social play probably represents a safe mechanism for immature subjects to test their personal abilities (self‐assessment), the strength/weakness of playmates, and the degree of cooperation/competition with them (social‐assessment). In the light of this new evidence, we can assert that play behaviour is far from being a purposeless activity, at least in the chimpanzee colony under study.     

Affiliation promotes the transmission of a social custom: handclasp grooming among captive chimpanzees

Handclasp grooming is a unique social custom, known to occur regularly among some, but not all populations of chimpanzees (Pan troglodytes). As with other cultural behaviors, it is assumed that this distinctive grooming posture is learned socially by one individual from another. However, statistical comparisons among factors thought to influence how a behavior spreads within a group have never, to our knowledge, been conducted. In the present study, the origination and spread of handclasp grooming in a group of captive chimpanzees was followed throughout more than 1,500 h of observation over a period of 12 years. We report on the frequency, bout duration, and number and demography of performers throughout the study period, and compare these findings to those reported for wild populations. We predicted that dyads with strong affiliative ties, measured by time spent in proximity to and grooming one another, were likely to develop a handclasp grooming partnership during the study period. A quadratic assignment procedure was used to compare correlations among observed frequencies of grooming and proximity with handclasp grooming in all possible dyads within the group. As predicted, the formation of new handclasp grooming dyads was positively correlated with the rate of overall grooming and proximity within a dyad. In addition, in nearly all dyads formed, at least one individual had been previously observed to handclasp groom. We concluded that affiliation and individual experience determines the transmission of handclasp grooming among captive chimpanzees.     

Description of the behavior of praying mantis with particular reference to grooming

Eighteen behavior patterns, encompassing most of the observable behavior of individually housed praying mantids, Sphodromantis lineola, were recorded using a point sampling technique. The data were sorted into four major behavioral categories: (1) food acquisition, (2) grooming, (3) inactivity, and (4) locomotion and miscellaneous. The mantids spent most of the time in an inactive state, which is consistent with their way of life as ambushing predators. Most of the animals' active time was spent in food acquisition (60%). Grooming behaviors comprised 16.7% of the active time; foreleg grooming represented 82% of grooming, while head grooming represented 14.3%. Analysis of the behavioral states in close temporal proximity to head grooming indicated that head grooming often follows foreleg grooming, occuring in bouts of about 1/2 to 1 min duration. Foreleg grooming is also closely associated with eating and seems to represent a pivotal behavior pattern between food acquisition and grooming, possibly sharing causal factors with both.     

Effect of resource competition on the long-term allocation of grooming by female baboons: evaluating Seyfarth's model

Seyfarth (1977, Journal of Theoretical Biology, 65, 671-698) proposed an influential model that explained the long-term patterning of grooming relationships between female primates in terms of an interaction between the idealized grooming objectives of females and competition for valuable grooming partners. A critical test of the model requires a demonstration not only that competition for partners exists, but also that females do have an underlying target for the amount of grooming that they would like to receive relative to the amount they need to give. As it is not possible to stipulate a priori what this target is, or to detect it directly, we assessed its applicability by making a set of predictions, within the framework of Seyfarth's model, as to how observed grooming patterns should change with changes in the intensity of resource competition. We tested these predictions with data from a troop of baboons, Papio hamadryas ursinus, for which the within-bout structure of grooming has already been shown to be sensitive to changes in resource competition (Barrett et al. 2002, Animal Behaviour, 63, 1047-1053). We found no evidence of competition for grooming partners and our results do not support the predictions of the modified model with respect to the existence of underlying grooming objectives. The findings that the grooming of female baboons is more diverse and that the mean rank distance separating partners increases when resource competition is greater, together with the absence of rank effects on long-term patterns, are, however, supportive of the recent biological market approach to social interactions. Copyright 2003 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.      

Using biological markets principles to examine patterns of grooming exchange in Macaca thibetana

Biological markets principles offer testable hypotheses to explain variation in grooming exchange patterns among nonhuman primates. They predict that when within-group contest competition (WGC) is high and dominance hierarchies steep, grooming interchange with other "commodity" behaviors (such as agonistic support) should prevail. In contrast, when WGC is low and gradients shallow, market theory predicts that grooming reciprocity should prevail. We tested these predictions in a wild, provisioned Tibetan macaque (Macaca thibetana) group across six time periods during which the group had been subjected to varying degrees of range restriction. Data on female-female aggression, grooming, and support were collected using all-occurrences and focal animal sampling techniques, and analyzed using ANCOVA methods and correlation analyses. We found that hierarchical steepness varied significantly across periods, but did not correlate with two indirect indicators of WGC (group size and range restriction) in predicted directions. Contrary to expectations, we found a negative correlation between steepness and group size, perhaps because the responses of group members to external risks (i.e. prolonged and unavoidable exposure to humans) may have overshadowed the effects of WGC. As predicted, grooming reciprocity was significant in each period and negatively correlated with steepness, even after we controlled group size, kinship, rank differences, and proximity. In contrast, there was no evidence for grooming interchange with agonistic support or for a positive relationship between interchange and steepness. We hypothesize that stressful conditions and/or the presence of stable hierarchies during each period may have led to a greater market demand for grooming than support. We suggest that future studies testing these predictions consider more direct measures of WGC and commodities in addition to support, such as feeding tolerance and access to infants.     

Trade‐offs in primate grooming reciprocation: testing behavioural flexibility and correlated evolution

Primates may trade altruistic behaviours, such as grooming, either for itself or for different rank‐related benefits, such as tolerance or agonistic support. Ecological conditions are expected to affect competition and thus the steepness of dominance hierarchies. This, in turn, may influence the value of the different currencies that primates exchange. Thus, it can be hypothesized that, as the dominance hierarchy becomes steeper, more grooming is directed up the hierarchy (in exchange for tolerance or agonistic support) and less grooming is exchanged for other grooming. We assembled a large database of within‐group grooming distribution in primates (38 social groups belonging to 16 species and eight genera) and tested these hypotheses both within species (i.e. comparing different groups of the same species) and between species (using comparative methods that control for phylogenetic relatedness). We found within‐species evidence that steeper dominance hierarchies were associated with more grooming being directed up the hierarchy, and that a trade‐off occurred between the tendency to groom up the hierarchy and the degree of grooming reciprocation (although, in some analyses, only a nonsignificant trend was observed). By contrast, phylogenetically controlled comparisons between species did not reveal evidence of correlated evolution between the steepness of the dominance hierarchy, the tendency to direct grooming up the hierarchy, and the degree of grooming reciprocation. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 95 , 439–446.     

Consortship and Mating Success in Chacma Baboons (Papio cynocephalus ursinus)

Chacma baboons (Papio cynocephalus ursinus) show a lower consortship take‐over rate and longer consortship duration than the other savannah baboons ( Bulger 1993 ). It has been argued that researchers have focused on atypically small troops with few adult males, resulting in low competition for access to oestrous females. Consortship data from two mountain baboon troops containing seven and four males, respectively, were analysed to determine whether the troop with the greater number of males showed a weaker correlation between mating success and rank due to an expected higher consortship take‐over rate. No consort take‐overs were observed in either study troop and mating success in both troops was correlated strongly with male rank. The distribution of days spent in consortship amongst the males could be explained by the priority‐of‐access‐model. The degree of cycle overlap determined the number of males observed consorting oestrous females, whereas the number of males did not influence the relationship between rank and consorting activity.     

Social Grooming in Bats: Are Vampire Bats Exceptional?

Evidence for long-term cooperative relationships comes from several social birds and mammals. Vampire bats demonstrate cooperative social bonds, and like primates, they maintain these bonds through social grooming. It is unclear, however, to what extent vampires are special among bats in this regard. We compared social grooming rates of common vampire bats Desmodus rotundus and four other group-living bats, Artibeus jamaicensis, Carollia perspicillata, Eidolon helvum and Rousettus aegyptiacus, under the same captive conditions of fixed association and no ectoparasites. We conducted 13 focal sampling sessions for each combination of sex and species, for a total of 1560 presence/absence observations per species. We observed evidence for social grooming in all species, but social grooming rates were on average 14 times higher in vampire bats than in other species. Self-grooming rates did not differ. Vampire bats spent 3.7% of their awake time social grooming (95% CI = 1.5–6.3%), whereas bats of the other species spent 0.1–0.5% of their awake time social grooming. Together with past data, this result supports the hypothesis that the elevated social grooming rate in the vampire bat is an adaptive trait, linked to their social bonding and unique regurgitated food sharing behavior.     

Social Relationships Among Ring-Tailed Lemurs (Lemur catta) in Two Free-Ranging Troops at Berenty Reserve, Madagascar

We observed two free-ranging troops of ring-tailed lemurs at the Berenty Reserve, Madagascar. Kinship affinities in these troops are known only for mothers and their offspring 4 years of age. We attempted to quantify social relationships. Almost all agonistic interactions were dyadic, and triadic agonistic interactions, such as alliances, were very rare. Dominance hierarchies in both sexes in the two troops were not linear. As in cercopithecine monkeys, mothers were dominant over their adult daughters. However, the daughters were not ranked immediately below their mothers. Close proximity and social grooming occurred more frequently between closely related females, such as mother–daughter and sister–sister dyads, than between unrelated females. Frequent-proximity relations also occurred between adult males that had emigrated from another troop and entered the present troop together, even though they did not rank closely to one another. Subordinates were likely to groom and to greet dominants more frequently than vice versa. During group encounters, particular females were involved in agonistic interactions with animals of other troops, regardless of dominance rank. Adult males, regardless of their dominance rank, but not adult females, constantly tried to drive solitary males away.     

Benefits, Costs and Constraints of Anti-Parasitic Grooming in Adult and Juvenile Rodents

Grooming behaviour plays various roles in the health care, reproduction, and social life of an individual vertebrate. However, the reasons for the variability in time spent grooming amongst species, populations and individuals are not fully understood. We tested the hypothesis that the main role of grooming is ectoparasite removal and thus that time spent grooming by an animal reflects the costs of parasite infestation offset against the costs of grooming. The test was conducted on a rodent, Meriones crassus, that is parasitised by a flea, Xenopsylla conformis. We monitored behaviour of juvenile and adult rodents before and after flea infestation and quantified the probability of mortality of fleas with respect to the time spent grooming in adults compared with juvenile rodents. We predicted that: (1) increased costs of flea infestation (e.g. in parasitised as opposed to flea‐free rodents and in juveniles as opposed to adults) increases time spent grooming and (2) mortality probability per flea increases with increasing time spent grooming and is higher for fleas on juveniles than for fleas on adult rodents. We were interested to discover at the expense of which activity grooming is increased. Our findings established that the major role of grooming is in flea removal, as exposure to fleas evoked grooming activity in all rodents and grooming activity explained 57–70% of the variation in flea mortality. Furthermore, we showed that the rise in grooming activity was at the expense of resting. However, we found only partial support for the predicted increase in grooming time with increasing costs of flea infestation. Flea infestation did indeed increase the time spent grooming by rodents. Nevertheless, juvenile rodents who incur higher costs of flea infestation spent less time grooming than adults and sustained similar flea densities, suggesting that these hosts are constrained by some other factors, such as feeding time.     

Proximity and grooming patterns reveal opposite-sex bonding in Rwenzori Angolan colobus monkeys (<Emphasis Type="Italic">Colobus angolensis ruwenzorii</Emphasis>)

Close proximity and social grooming are important bonding mechanisms in primates. These behaviors show the social structure of a species and many studies have found positive correlations between the degree of kinship and grooming and proximity. We used 1 year of data collected via instantaneous scan sampling on a large “supertroop” of Colobus angolensis ruwenzorii at Lake Nabugabo, Uganda, to examine partner preferences for grooming and nearest neighbors in each age-sex class. Little is known about this species, so we based our hypotheses on congeners. Of the five species of black-and-white colobus, data on sex-biased dispersal patterns are available for three (C. guereza, C. vellerosus, and C. polykomos), all of which show male-biased dispersal with occasional female dispersal. We thus predicted that female C. a. ruwenzorii would be more strongly bonded than males, showing greater proximity and grooming. We did not expect bonding between the sexes since congeners do not show this pattern. We found that among adult dyads, males and females were more likely to be found in loose proximity, and to groom, than would be expected given group composition. Conversely, both males and females had relatively weak same-sex relationships. Between the sexes, adult males had higher proximity and grooming indices with adult females without infants than with females with infants. These observations indicate that this subspecies is cross-bonded and that both sexes may disperse. Furthermore, our findings suggest that the social organization and social structure of C. a. ruwenzorii differ greatly from other black-and-white colobus species.     

A functional analysis of social grooming patterns through direct comparison with self-grooming in rhesus monkeys

Social grooming in primates is a complex behavior in which monkeys stroke, pick, or otherwise manipulate a companion’s body surface. While grooming has been associated with important social functions, researchers who have examined its physical characteristics, such as body site preferences, have focused on its role in skin care and ectoparasite removal. Whether the form of social grooming is constrained primarily by utilitarian or social functions was empirically tested by directly comparing this behavior with self-grooming, which was assumed to have primarily utilitarian functions. Predictions made concerning social grooming, based on a comparison with self-grooming, were tested by examining site preferences, duration of grooming (overall and to specific body sites), and method of grooming (stroking, picking, or a combination of the two) in rhesus monkeys. None of these predictions was verified. The physical characteristics of social grooming could not be predicted from the way an animal groomed itself. There was no relationship between site preferences in these two types of grooming. Animals groomed others for longer periods of time than they groomed themselves, both overall and when grooming specific sites. The methods these animals used differed markedly in self-and social grooming: they primarily picked at their own hair or skin but, when grooming others, varied their technique across sites, stroking the hair where it was thickest and picking where the hair was sparse. These results suggest that utilitarian functions are not the most important factors constraining the form of social grooming.     

Community composition, correlations among taxa, prevalence, and richness in gastrointestinal parasites of baboons in Senegal, West Africa

Studies of gastrointestinal parasite prevalence in Papio have either focused on a single troop or compared prevalence among troops that share migrants but differ in degree of human contact. Little is known about the extent of variation in prevalence where obvious factors that may drive prevalence (e.g., human contact) are absent, so it is difficult to interpret variation when these factors are present. To address this issue, we studied troops of Guinea baboons (Papio papio) that had almost no contact with humans or domesticated species of plants or animals. We tested the null hypotheses that community composition, richness, and prevalence would be similar between groups in two comparisons: (1) between troops in the same locality with no known differences in drivers of prevalence, and (2) between samples at the same location taken more than 20 years apart. We collected anonymous fecal samples from two troops of baboons living in a wilderness site, Mt. Assirik, in the Niokolo-Koba National Park, Republic of Senegal, West Africa. We collected samples from two valleys and analyzed prevalence and richness with respect to place and time. Both prevalence and richness were similar in the two valleys, but significant changes emerged in both prevalence and community composition compared with the previous survey in 1978–1979. We also found that the nematode Enterobius and a fluke, Watsonius, co-occurred within hosts more frequently than expected. This phenomenon has not been previously noted in the literature, and it suggests common environmental drivers or facilitation among these parasites.     

Differential effects of kinship,dominance, and the mating season on female allogrooming in a captive group ofMacaca fuscata

An analysis of allogrooming (total times spent grooming individual partners) of 8 sexually mature females (3–12 years of age) in a captive group of 17 Japanese macaques, shows that during the nonmating season, grooming distributions were characterized by high proportions of grooming given to family members and/or higher ranking nonkin. During the mating season, all eight females showed significant shifts in their grooming distributions, and four females showed significant shifts in grooming between their nonestrous and estrous periods (defined behaviorally). Fox six of eight females, mating season grooming was characterized by either high proportions of grooming given to family members and/or heterosexual and homosexual partners. It was found that within dyadic sexual relationships, dominants gave more grooming to subordinates than the former received, in contrast to a reversal of this pattern in the majority of these same dyads during the nonmating season. This is interpreted as one short-term function of grooming: a dominant asymmetrically grooms a subordinate sexual partner to maintain proximity with (or reduce tension in) the latter. The two remaining focal females (middle ranking, nulliparous) differed from the other females in that they shifted their mating season grooming to subordinate nonkin, despite the lack of evidence that this was a result of sexual interactions, patterns of partner availability, competition, patterns of grooming reciprocity, or agonistic alliance support. From these results, it is suggested that in some contexts, grooming of subordinate nonkin may function to reduce tension in thegroomer. In the Japanese macaque, this latter possibility and the asymmetric grooming of subordinate homosexual partners may prove to be exceptions to the general rule that female cercopithecine grooming of nonkin flows up the dominance hierarchy.     

Market powers predict reciprocal grooming in golden snub-nosed monkeys (Rhinopithecus roxellana)

Social grooming is a common form of affiliative behavior in primates. Biological market theory suggests that grooming can be traded either for grooming or other social commodities and services. When no other services are exchanged, grooming is predicted to be approximately reciprocated within a dyad. In contrast, the amount of reciprocal grooming should decrease as other offered services increase. We studied grooming patterns between polygamous male and female in golden snub-nosed monkeys (Rhinopithecus roxellana) from the Qinling Mountains of central China and found that about 29.7% of grooming bouts were reciprocated. However, the durations of grooming bouts offered and returned was asymmetrical within dyads. In bisexual dyads, more grooming was initiated by females than males, which became more pronounced as the number of females per one-male unit increased. The rate of copulation per day for each female was positively correlated with the total duration of grooming time females invested in males.. Females without an infant (non-mothers) directed more grooming towards females with an infant (mothers) and were significantly more likely to be non-reciprocated. There was a significant negative relationship between non-mother and mother grooming duration and the rate of infants per female in each one-male unit. High-ranking females also received more grooming from low-ranking females than vice versa. The rate of food-related aggressive interactions was per day for low-ranking females was negatively correlated with the duration of grooming that low-ranking females gave to high-ranking females. Our results showed that grooming reciprocation in R. roxellana was discrepancy. This investment-reciprocity rate could be explained by the exchange of other social services in lieu of grooming.     

Whom to Groom and for What? Patterns of Grooming in Female Barbary Macaques (Macaca sylvanus)

Grooming is one of the most conspicuous social interactions among nonhuman primates. The selection of grooming partners can provide important clues about factors relevant for the distribution of grooming within a social group. We analyzed grooming behavior among 17 semi-free ranging female Barbary macaques (Macaca sylvanus). We tested whether grooming is related to kinship, rank and friendship. Furthermore, we tested whether grooming is reciprocated or exchanged for rank related benefits (i.e. lower aggression and increased tolerance whilst feeding). We found that in general grooming was reciprocally exchanged, directed up the hierarchy and at the same time affected by friendship and kinship. Grooming was more frequent among individuals with higher friendship values as well as amongst related individuals. We also divided our data set on the basis of rank difference and tested if different power asymmetries between individuals affected the tendency to exchange grooming for rank related benefits and grooming reciprocation. In support of our initial hypothesis our results show that the reciprocation of grooming was a significant predictor of grooming interactions between individuals of similar rank, but not between those individuals more distantly separated in the social hierarchy. However, we did not find any evidence for grooming being exchanged for rank related benefits in either data set. Our results, together with previously published studies, illustrate the behavioral flexibility of macaques. It is clear that multiple studies of the same species are necessary to gather the data required for the solid comparative studies needed to shed light on patterns of grooming behavior in primates.