滇金丝猴雌性个体间的理毛行为

相互理毛行为广泛存在于社会性群居灵长类动物中,通常具有清洁卫生和社会交往功能。2012 年10 月至2013 年6 月,我们在云南白马雪山国家级自然保护区对一人工辅助投食滇金丝猴群,采用全事件取样法和焦点动物取样法收集了雌性个体间相互理毛的行为数据,包括理毛的部位、理毛的姿势、理毛的时间和回合数。研究结果表明:滇金丝猴雌性个体之间每次相互理毛的平均时间为5. 7 min。相互理毛部位较多的发生在自我理毛不能进行(达到)的部位(61.1% );在不能自我理毛部位的相互理毛行为持续时间长,平均9.7 min;在个体能够进行自我理毛部位的相互理毛持续时间短,平均为3. 2 min。相互理毛的姿势以对坐为主(48. 4% ),不同理毛姿势的理毛时间差异显著。新迁入家庭单元的雌性个体为理毛的首先发起者,但其获得被理毛的时间却并不多。滇金丝猴雌性个体相互理毛部位、理毛姿势和理毛时间的差异表明,它们之间的相互理毛行为符合卫生功能假说和社会功能假说。     

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.     

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.     

Conditional allogrooming in the herb-field mouse

Among members of the family Muridae, the herb-field mouse, Apodemus microps, is unique in that aggression is almost entirely lacking.This species, therefore, is a model organism for experimentalstudies of social behavior without the confounding influenceof aggression. We used video surveillance cameras to assessthe importance of self-grooming and allogrooming in the sociallife of this species. Detailed analysis of individual behavioralsequences using Markov chain methods revealed that self-groomingis a relatively stereotypic, sex-independent activity usually lasting about 8 s. Allogrooming is conditional in the herb-fieldmouse, because it takes the form of a reciprocal strategy,with the differences between nonmatching bouts varying accordingto whether the initiator of allogrooming is male or femaleand whether both interactants are of the same or opposite sex.Our analysis revealed that the exchange of allogrooming bouts between individuals of the same sex is reciprocal, but thatmales allow females to "defect" more often than vice versa,and males groomed females for longer than predicted by thedistribution of individual self-grooming bouts. In those specieswhere the demand for mating by males is far greater than thatoffered by females, in other words where females may selectmates, asymmetry of allogrooming may provide a mechanism forfemales to test the "suitability" of males for mating. It mayalso provide the means for males to stimulate females before mating. Furthermore, allogrooming was the only sex-dependentbehavior of the several tested in our experiment. As such,we suggest that allogrooming is the predominant premating mechanismin this species.     

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.     

Mating season influence on allogrooming in a confined group of Japanese macaques: A quantitative analysis

Three different quantitative parameters (frequency, duration and distribution) were used for studying allogrooming behavior in and outside the mating season in a Japanese macaque social group confined at the Rome Zoo. On the whole, 106 hr of observations were made using an “all occurrences” recording technique. Although individual grooming scores were collected, the quantitative analyses were mostly focused on the relationships between and within the age/sex classes. The mating season caused two basic changes in allogrooming: (1) an amount increase; and (2) a widening of individuals' range of interactions. Strikingly, the former variation proved to be widely independent of the latter. Relationships between the age/sex classes changed so that the mature females became the main target of grooming from other group members, male and female. On the contrary, two interactional trends did not seem to be affected by the mating season: the tendencies to groom agemates chiefly and to interact with relatives closely. However, the reorganization of grooming relationships did not appear to weaken the group cohesion. Abstract of this paper was read at the 8th Congress of the International Primatological Society, Florence, July 7–12, 1980.     

Allogrooming and social status: An assessment of the contributions of female behavior to the social organization of hamadryas baboons (Papio hamadryas)

Three isosexual social groups, each containing ten subadult female hamadryas monkeys (Papio hamadryas) were studied for seven months to test three hypotheses dealing with the assumptions underlyingSeyfarth's (1977) model of allogrooming and social organization. Aggression, avoid and allogrooming behaviors were used as criteria for studying the social organization of the groups. UsingLandau's (1951) index and discriminant analyses, we found that each of the three isosexual female social units conformed to a model of social organization having a non-linear hierarchy and only two major strata: a dominant animal and subordinates who were largely undifferentiated. This aspect of social organization is similar to the normal one-male unit leader harem form of social organization that is typical of hamadryas. However, since no male was present, the role of unit leader was filled by a female. The length of allogrooming bouts and the amount of allogroom received was affected by the social status of the recipient, with high status individuals receiving more than low status individuals. Social peers were not observed competing for access to high status individuals and did not exchange most of their grooming among themselves. We found that the assumptions underlyingSeyfarth's (1977) model were not appropriate for the type of social organization typically found in hamadryas monkeys, thus suggesting the need for further modification of the model so that it fits available data.     

Pre-copulatory behaviour in the male Mongolian gerbil: I. Differences in dependence on androgen of component patterns

Male behaviour patterns, including ultrasonics, olfactory investigation, grooming and sequences of following of oestrous females during the pre-copulatory period, were described for the Mongolian gerbil. Differences in dependence of these patterns on gonadal hormones were examined by measuring the rates of decline after castration and the degree of restoration following the subcutaneous injection of testosterone propionate (20 μg/2 days/animal). Castration and androgen therapy did not influence the performance of male genital grooming, allogrooming and the olfactory investigation of both female secretory products and the female's body, excluding the posterio-dorsal area. The other male patterns differed in the extent to which they were affected. Thus ventral gland marking, foot-stomping and sequences of follow/dart interactions declined rapidly and were not restored to pre-castration levels by androgen; whereas the upsweep ultrasonic vocalization and olfactory investigation of the female's perineal area declined more gradually, and were completely restored. These consistent differences in both decline and restoration suggest that mechanisms underlying some pre-copulatory patterns are influenced by androgen to a greater degree than others.     

Social behaviour and infant carrying in a group of moustached tamarins,Saguinus mystax (primates: Platyrrhini: Callitrichidae), on Padre Isla,Peruvian Amazonia

The social behaviour of a group of eight moustached tamarins,Saguinus mystax, (five males, three females) was studied on Padre Isla in northeastern Peru. About 60% of all allogrooming was done by the two adult males in the group, and about 11% by a young adult female. All other group members groomed very little. The adult breeding female received more grooming than any other group member. After the death of the adult female (preyed upon by an anaconda) the amount of active allogrooming remained constant for all group members except for the young adult female, who increased her contribution to about 30%. Her preferred grooming partner was the subadult female, which generally screamed when being groomed by the young adult female and terminated grooming by going away. This kind of grooming relation is termed “forced grooming” and is interpreted as a possible social control mechanism. The young adult female groomed the adult males more often after the death of the adult female than before. This might have had the function of strengthening the social bond with the adult males and in obtaining the breeding position in the group. After the death of the adult female, the vulva of the young adult female grew to full adult size. Agonistic behaviour was less frequent than allogrooming. Most aggressive interactions (50%) originated from the subadult male of the group. The young adult female was the target of most of these aggressions. Extremely little aggression occurred between the three females. The young adult female was the only individual who tried to emigrate from the group during the study period. Her attempt to join a neighbour group failed due to rejection by all four members of this group. All group members participated in carrying an infant, but the adult males and the young adult female carried most frequently. Contribution to infant carrying varied with the infant's age.     

Decision making in grooming by Japanese macaques (Macaca fuscata)

I analyzed the temporal organization of individual Japanese macaques’ (Macaca fuscata) grooming sequences in 14 mothers and 13 offspring of different age/sex classes and 4 nonkin females. I hypothesized that preceding grooming affects subsequent grooming by the same individual. Grooming bouts were likely to be terminated as the bouts became longer when females groomed nonrelatives. Moreover, the duration of first bouts was longer than that of following bouts. These effects were also seen in grooming of mothers by their offspring > 1 year old and that of adult and adolescent female offspring by their mothers. In contrast, neither the duration of first bouts nor the number of preceding bouts had much effect on the occurrence or duration of subsequent bouts in any subject.     

Age-related differences in social grooming among adult female Japanese monkeys ( Macaca fuscata)

The present study investigated the influence of dominance rank in combination with kinship on age-related differences in social grooming among adult females in a free-ranging group of Japanese monkeys (Macaca fuscata). Eighty-three adult females were divided into six sub-groups according to age-class (younger: 5–9 years old; middle: 10–14 years old; older: 15–22 years old) and dominance rank (high and low rank). The ratio of the number of unrelated females that each female groomed to the total number of available unrelated females and grooming bouts which she gave to unrelated females decreased with increasing age for both high- and low-ranking females, whereas age did not appear to affect corresponding values for related females. On the other hand, compared with low-ranking females, high-ranking females of all age-classes received grooming more often from a larger number of unrelated females. Moreover, older females of low rank received grooming less often from a smaller number of unrelated females than younger females of low rank. These results indicate that with increasing age females are more likely to concentrate on related females when they have grooming interactions with other females. This tendency seems to be more apparent for low-ranking females. Moreover, the present findings also indicate that older high-ranking females could maintain their social attractiveness as high as younger high-ranking females.     

Comparison of colony foundation success between sexual pairs and female asexual units in the termite Reticulitermes speratus (Isoptera: Rhinotermitidae)

In termites, a male and a female usually found a colony cooperatively. However, pairing efficiency tends to be low in Reticulitermes speratus because of a limited mate-searching range, the female-biased sex ratio, and a relatively low calling ability. Females that fail to pair with males found colonies either in female–female pairs or even alone. In the laboratory, we examined colony foundation by single females (F), female–female pairs (FF), and normal male–female pairs (FM). The time until colony foundation (when termites began excavating wood baits) differed significantly among the unit types. Time until excavation was much longer for single females than for FF and FM units, which reflects the relative success of colony foundation. The survival rate of single females was also significantly lower than that of FF- and FM-unit females, although there was no difference between FF and FM units. This result demonstrates that cooperation, even female–female, promotes female survivorship. Nevertheless, the number of progeny per female was significantly lower in FF units than in FM units, possibly because females of FF units must share reproductive output. These results lead us to the conclusion that a normal monogamous pair is the best unit for colony foundation. Nevertheless, females alone can establish colonies by parthenogenesis, and even female–female cooperation promotes colony foundation success if pairing with males is not possible. Considering the functional decision for females in F and FF units of how much time to spend searching for a male mate, we believe that these facultative pathways of colony foundation by parthenogenesis have adaptive significance. Received: November 30, 2000 / Accepted: March 6, 2001     

Allogrooming Behavior and Grooming Site Preferences in Captive Bonobos (Pan paniscus): Association with Female Dominance

I tested the utility of Seyfarth's (1977) model of rank-related attractiveness to explain the distribution of allogrooming behavior among captive bonobos (Pan paniscus). Adult female bonobos generally have high social status and may be dominant over males. As predicted by the model, I found that high-ranking adult females received most allogrooming within each of the four investigated groups. Among adult female-adult female dyads, however, allogrooming was not clearly associated with dominance rank. Contradictory to predictions of the model, the highest-ranking females were responsible for most displacements over allogrooming, and grooming competition is positively correlated with dominance rank. In the second part of this study, I investigated the social significance of allogrooming body site preferences. Bonobos direct significantly most allogrooming to the face of conspecifics, and high- and low-ranking individuals, as well as males and females, differ significantly in their preferences for certain allogrooming sites. Subordinates and males tended to avoid facial grooming and preferred the back and anogenital region, while high-ranking individuals and females directed most allogrooming to the face and head of grooming partners. Data from this study support the hypothesis that high-ranking females are the most attractive grooming partners within a female-centered bonobo society. Many other aspects of allogrooming behavior, however, are not consistent with the model of rank-related attractiveness.     

Benefits to Female Helpers in Wild Rhinopithecus roxellana

To assess what female Sichuan snub-nosed monkeys (Rhinopithecus roxellana) gain from allowing others to care for their infants, we collected behavioral data on 12 mother-infant dyads at Zhouzhi National Nature Reserve in the Qinling Mountains, China. Mothers’ feeding time significantly increased when infants were cared for by other group members versus when they were cared for by the mothers themselves. The time mothers spent autogrooming and receiving grooming also increased when they were temporarily relieved of maternal duties; however, mothers did not groom other individuals more when they were not encumbered by infants. There are several benefits that mothers gain from having helpers care for their infants: They gain more time to feed and thus increase their feeding efficiency. Mothers have more time to engage in hygienic and maintenance activities because they autogroom and receive allogrooming more. Lastly, mothers save energy when their infants are with helpers. Wild Sichuan snub-nosed monkey mothers meet their basic survival and maintenance needs because of helping behavior.     

Group unity of chimpanzees elucidated by comparison of sex differences in short-range interactions in Mahale Mountains National Park,Tanzania

Chimpanzees (Pan troglodytes) form multi-male and multi-female unit groups with fission–fusion grouping patterns. Short-range interaction (SRI) plays an important role in the unity of these groups and in maintaining social bonds among members. This study evaluated three models of chimpanzee social structure that differed according to the emphasis each placed on social bonds between the sexes, i.e., the male-only, the bisexual, and the male-bonded unit-group model. I investigated differences in SRI between the sexes among group members in well-habituated wild chimpanzees in Mahale Mountains National Park, Tanzania. I followed six focal adult males and six females, and quantified their respective SRI with other chimpanzees. Except between subordinate males and adult females, adults in general engaged in SRI with about 60–90% of the individuals with whom they made visual contact each day, whether in large or small parties. Although the number of social grooming (SGR) partners was limited, male–male SGR networks were wider than were either male–female or female–female SGR networks among adults. The number of contact-seeking behavior (CSB) partners was also limited, but dominant males had more CSB partners. Adult females mainly interacted by pant-grunt greeting (PGG) with adult males, but tended to do so mainly with the highest-ranking male(s) within visual contact. These results indicated that the social bonds among adult males were essential to group unity. Because of clear male dominance, adult females established peaceful coexistence with all group members despite less frequent SRI with subordinate males by maintaining affiliative social bonds with dominant males, thereby supporting the male-bonded unit-group model. Adult females had many female SRI partners, but these interactions did not involve performing conspicuous behaviors, suggesting that females maintain social bonds with other females in ways that differ from how such bonds are maintained with and between adult males.     

Grooming patterns in Verreaux's sifaka

Lemur grooming has received very little attention in the literature. Nevertheless, allogrooming in lemurs has been suggested to be fundamentally different from the grooming of anthropoids. One reason is that lemurs generally rely on oral rather than manual grooming. Lemur allogrooming has also been suggested to serve less of a social function than has been attributed to anthropoid grooming. I analyzed the allogrooming behaviors of 29 Verreaux's sifaka (Propithecus verreauxi) living in five social groups in the Kirindy Forest of Madagascar. Based upon 1,586 observation hours, I found that sifaka, like anthropoids, spend very little time mutual grooming (2±3%). Half of all allogrooming involved parts of the body that could have been easily groomed by the recipient, such as the limbs. Even though ectoparasite loads are expected to be greater during the rainy season, allogrooming did not increase during the rainy season. Allogrooming rates were influenced by both rank and sex, and increased by 50–100% during the mating season. The results of this study suggest that allogrooming in Verreaux's sifaka plays an important social function, even though it is performed with a toothcomb. Am. J. Primatol. 72:254–261, 2010. © 2009 Wiley‐Liss, Inc.     

Effects of Relatedness,Dominance, Age,and Association on Reciprocal Allogrooming by Captive Impala

Wild impala display a highly reciprocal allogrooming system that, by virtue of its frequency and high degree of reciprocity, is unique among ungulates. A herd of 35 free-ranging captive impala provided opportunity to examine the degree of reciprocity of allogrooming exchanges and the influence of relatedness, dominance, age and association on partner preferences and distribution of grooming between allogrooming partners. As in wild impala, the exchange of allogrooming bouts in the captive impala was highly reciprocal regardless of partners. Kinship and dominance had no influence on partner preference or distribution of grooming between partners. Although mothers showed a significant preference to allogroom with their unweaned offspring, this preference practically disappeared with older offspring. Age-mates (no greater than 6 mo apart) tended to associate with one another and spatial proximity was positively correlated with grooming partner preference. It was not clear whether impala actively sought out age-mates for grooming, or randomly chose grooming partners from nearby age-mates. The failure to find a role for kinship and dominance is counter to what has generally been found in most Old World terrestrial primate studies. The absence of pronounced social influences, coupled with the known effectiveness of grooming in removing ectoparasites, suggest that a utilitarian role, especially removal of ticks, is an important function of the impala reciprocal allogrooming system.     

Reciprocal Allogrooming in Dam-reared and Hand-reared Impala Fawns

Among adult females and males of African antelope impala are unique in their performance of reciprocal allogrooming. The occurrence of this behaviour in neonatal impala fawns was explored in a free-ranging impala herd at the San Diego Wild Animal Park where 5 dam-reared fawns were observed from birth through 10 weeks of age. One-way maternal grooming and reciprocal allogrooming with the dam and non dam partners emerged as distinct behavioural systems. Maternal grooming, directed mostly to the anogenital area, was typical of that seen in other ungulates, and sharply declined over the first two weeks. Reciprocal allogrooming, characterized by alternate exchanges of grooming bouts with a partner in the same manner as in adults, was seen as early as 3–8 d after birth. All fawns were grooming with unrelated adult females by the end of the second week. By week 2 virtually every measure of reciprocal allogrooming by fawns (grooming delivered per hour, reciprocity, and percent of encounters initiated) was as high as for adults. The appearance of this reciprocal allogrooming pattern, especially at such an early age, appears to be unique among ungulates, and possibly mammals in general. Three hand-reared impala fawns, deprived of the opportunity to interact with older herdmates, but having access to impala fawns and heterospecific fawns, were observed from 1–3 mo of age. The hand-reared impala showed no alteration in the occurrence of reciprocal allogrooming behaviour compared with the dam-reared control fawns, indicating that allogrooming experience with older animals was not required for the appearance of reciprocal allogrooming at an early age. Interestingly, hand-reared fawns persisted in grooming heterospecific fawns despite the fact that heterospecifics rarely reciprocated grooming. We postulate that the strong predisposition for impala young to groom others may be related to the threat of tick infestation in the impala's ecotone habitat.     

Group harmony in gibbons: Comparison between white-handed gibbon (Hylobates lar) and siamang (H. syndactylus)

The siamang (Hylobates syndactylus) is exceptional among gibbons in that its area of distribution almost completely overlaps those of other gibbons, namely the white-handed gibbon (H. lar) and the agile gibbon (H. agilis) of the lar group. The siamang has almost twice the body weight of the gibbons of the lar group (ca. 11 kg vs. 5–6 kg), and it has been suggested that distinct ecological and behavioural differences exist between the siamang and its two sympatric species. The siamang has been claimed to differ from the white-handed gibbon “in the closer integration and greater harmony of group life” (Chivers, 1976, p. 132). However, few quantitative data exist to support this hypothesis. In the present study, intra-group interactions in captive family groups of white-handed gibbons and siamangs (two groups of each species) were recorded by focal-animal sampling. These data failed to show a consistent association between species and most of the behavioural patterns recorded, such as frequency of aggression, percentage of successful food transfer, frequency of social grooming bouts, and duration of social grooming/animal/hr. A significant difference was found for only two of the variables: Individual siamangs in this study showed longer grooming bout durations, and made fewer food transfer attempts than lar individuals. Only the first of these two differences is consistent with the hypothesis mentioned above, whereas the lower frequency of food transfer attempts in siamangs is the opposite of what should be expected under the hypothesis. On the other hand, two of these behavioural patterns showed a significant correlation with the parameters group size and individual age: Both individuals in larger groups and younger individuals tended to show shorter grooming bouts and a smaller proportion of successful food transfers. Our findings indicate that social cohesion within these gibbon groups may be much more flexible according to and depending on social or ecological influences and less rigidly linked to specific gibbon taxa than previously assumed. A considerably larger number of gibbon groups would have to be compared to provide reliable evidence for or against species-specific differences in group cohesion. Another finding of this study—a positive correlation between the frequency of aggression and grooming—is discussed in the light of the functional interpretations commonly attributed to allogrooming behaviour in primates.     

The trade balance of grooming and its coordination of reciprocation and tolerance in Indonesian long-tailed macaques (<Emphasis Type="Italic">Macaca fascicularis</Emphasis>)

We collected data on grooming, proximity, and aggression in long-tailed macaques (Macaca fascicularis) in Kalimantan, Indonesia. We used this data to study how grooming influenced a receiver's (B) behavior towards the bout's initiator (A). In our first analysis, post-grooming samples were collected after A groomed B. These were compared to matched-control samples of similar conditions but A had not previously groomed B. This comparison was performed on 26 individuals (16 female, 3 male, 7 immature) and tested whether A's initial act of grooming increased the pair's time in proximity and the amount of time B groomed A. We also tested if A's grooming decreased B's aggression towards A per time in proximity. Rates of B-->A aggression per time in proximity with A for 39 individuals (18 female, 5 male, 16 immature) were compared between post-grooming and focal sample data. Finally, we studied 248 grooming bouts to test if the first two grooming episodes were time matched. We assessed the influence of age, sex, rank and inferred kinship on time matching, and controlled for individual variation and tendency to groom using a general linear mixed model. Our results showed that A-->B grooming acted to increase B-->A grooming and the pair's proximity, while lowering B-->A aggression. Despite these effects, episodes in grooming bouts were generally not matched, except weakly among similar partners (i.e., female pairs and immature pairs). Grooming imbalance was greatest across age-sex class (i.e., male-female and adult-immature pairs). In similar pairs, grooming duration was skewed in favor of high-ranking individuals. We conclude grooming established tolerance and increased the likelihood that grooming reciprocation would occur, but grooming durations were not typically matched within bouts. Lack of time matching may be the result of grooming that is performed to coordinate interchanges of other social services.