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Extended breeding bonds and direct paternal care are rare in group-living species with high levels of male–male competition. In polygynandrously mating savannah baboons, many males form close ties (primary associations) to certain females outside the mating context. These relationships have likely evolved as a form of male parenting effort because roughly 50–75% of primary associates are the sires of the females' current infants. Mismatches between the formation of primary associations and paternity have been interpreted as kin recognition errors, which arise because males rely on imperfect proxies of paternity. Alternatively, mismatches may reflect prior paternity history if males form enduring relationships with the mothers of their offspring. We tested these hypotheses in a wild population of olive baboons, Papio anubis. The behaviour of sires near the time of conception was considerably different from the behaviour of nonsire primary associates, suggesting that most males were not misled by ambiguous behavioural cues of paternity. Instead, previous paternity history was an important predictor of the strength of ties between males and lactating females. Both paternity of the current infant and paternity of the previous infant influenced the probability that males would establish close ties to females, and these effects were largely additive. These findings indicate that male–female bonds in olive baboons extend long past lactation and suggest that selection may have favoured prolonged paternal investment in offspring. • Female olive baboons form long-lasting ties to the sires of their offspring. • Male–female ties reflect current and past paternity history. • Mismatches between paternity and mother–male bonds are not kin recognition errors. • Extended mother–sire association is evidence for extended paternal care. [ABSTRACT FROM AUTHOR]

Female copulation calls are species specific, distinct vocal signals sometimes given during or shortly after mating. Despite being common in primates and despite much empirical work, their function remains largely unclear for most species. Here, we used an information-theoretic approach to examine simultaneously three main competing hypotheses for the evolution of copulation calls. Two of the three hypotheses predict that female copulation calls function to incite competition between males, either directly (the male–male competition hypothesis) or indirectly (the sperm competition hypothesis), while the third predicts that females use calls to choose mating partners (the female choice hypothesis). We collected data on copulations of wild female olive baboons in Kibale National Park, Uganda, to compare the relative support for these hypotheses by modelling whether or not females produced copulation calls after mounts. Our analytical approach enabled us to objectively rank models corresponding to the three hypotheses according to how well our data fitted the models. Our data favoured the sperm competition hypothesis over the female choice hypothesis although much variation in calling remained unexplained. The male–male competition hypothesis seems unlikely given our data. We also discuss the possibility that copulation calls have no function, functions not included in our analysis, or that they are multifunctional, a reflection of the species' social evolution history. [ABSTRACT FROM AUTHOR]

According to socioecological theory, ecological pressures acting on females play an important role in shaping social organization, dispersal patterns and the nature of female–female relationships. However, there has been relatively little consideration of how females' relationships with males may influence the nature of females' relationships to other females. Here, we show that female olive baboons form well-differentiated relationships with adult males and these ties influence their relationships with other females. As in other species of savanna baboons, female olive baboons show pronounced preferences for close kin, but related females do not often share the same top-ranked male partners. Shared associations with males bring females into more frequent contact with distant kin and nonkin. The combined effects of bringing distantly related and unrelated females together and separating close kin reduced the extent of nepotistic biases among females in the study groups compared to female yellow baboons, Papio cynocephalus , and chacma baboons, Papio ursinus . These data suggest that selective pressures acting on both females and males may influence the nature and function of female–female relationships. [ABSTRACT FROM AUTHOR]

Colour signals arise in a variety of sexual contexts, including advertising reproductive status. Despite potentially attracting negative attention from unrelated competitors, bright pregnancy coloration may communicate gestation to kin and potential fathers, thereby garnering aid during agonistic encounters and reducing the overall amount of aggression received by pregnant females. To establish whether this ‘pregnancy sign’ influences rates of aggression in the presence versus absence of maternal kin, we conducted behavioural observations of wild olive baboons, Papio anubis , in Gombe National Park, Tanzania, in groups composed of maternal kin and nonkin, and of captive baboons at the Southwest National Primate Research Center (SNPRC, San Antonio, TX, U.S.A.), in group enclosures that were unlikely to include close kin. At SNPRC, we also experimentally obscured the coloration of the pregnancy sign, and we performed playback experiments to measure male responses to the distress calls of pregnant females. Free-ranging female baboons experienced significantly less aggression from nonkin females after the onset of the pregnancy sign compared to the pre-pregnancy sign. In contrast, captive pregnant females whose pregnancy coloration was obscured with paint experienced significantly lower aggression rates from female conspecifics compared to pre-painting. Male aggression towards females did not differ in the presence versus absence of the pregnancy sign in either the wild or the captive population, although captive fathers paid significantly more attention to distress calls of pregnant cage-mates than they did to those of cycling cage-mates, suggesting a willingness to aid mothers that were carrying their unborn offspring. [ABSTRACT FROM AUTHOR]

Although nonhuman primates' gestural communication is often considered to be a likely precursor of human language, the intentional properties in this communicative system have not yet been entirely elucidated. In particular, little is known about the intentional nature of monkeys' gestural signalling and related social understanding. We investigated whether olive baboons can (1) adjust their requesting gestures to the visual attention of the experimenter with special emphasis on the state of the eyes (open versus closed), and (2) flexibly tailor visual and auditory-based gestures to elaborate their communication as a function of whether or not the experimenter can see them. Using a food-requesting paradigm, we found monkeys able to favour either visual or auditory-based requesting gestures to match the experimenter's visual attention. Crucially, when the human was not visually attending, they silenced visual gestures to some extent but performed more attention-getting gestures. This is, to our knowledge, the first report of monkeys elaborating attention-getting signals to compensate for communication breakdown. Gestural communication was also supported by gaze alternation between the experimenter's face and the food, especially when the human was visually attending. These findings offer evidence that olive baboons understand the state of the eyes in others' visual attention and use requesting gestures intentionally. They emphasize that Old World monkeys shift to acoustic communication when the recipient is not visually attending. In contrast to that of human infants and great apes, this acoustic communication is purely gestural, not vocal. [Copyright &y& Elsevier]

Examines the laterality for maternal cradling and infant nipple preferences in olive baboons, Papio anubis. Determination of lateral bias for both maternal and infant behavior; Analysis of population-level handedness; Assessment on the lateral bias in hand use.

Investigates the effect of nearest neighbors' relative dominance status on the social behavior of sexually mature female olive baboons, Papio anubis. Validity of self-directed behavior (SDB) as a measure of relationship security during potential social anxiety; Variation in SDB response according to the nature of the dominant individual.

Examines the social spatial mechanisms of feeding competition among adult female olive baboons. Rank-related differences in food intake; Rate at which other animals were supplanted from feeding sites; Number of neighbors; Supplant ratio.

Examines feeding competition behavior among female olive baboons. Dominance rank; Nutrient acquisition rates; Dietary diversity or quality; Activity budgets; Link of female rank and fertility; Implications for models of female social structure and maximum group size.