Julie Gros-Louis

Social Conventions in Wild White‐faced Capuchin Monkeys

Ten researchers collaborated in a longterm study of social conventions in wild whitefaced capuchin monkeys, involving examination of a 19,000hour combined data set collected on 13 social groups at four study sites in Costa Rica over a 13year period. Five behavior patterns qualified as social traditions, according to the studys criteria: handsniffing, sucking of body parts, and three types of games. Some conventions were independently invented in virtually identical form at multiple sites. The extinction of several conventions was observed during the course of the study; it appears that they rarely last longer than ten years. It is hypothesized that the monkeys are using these group or cliquespecific social conventions to test the quality of their social relationships.Ten researchers collaborated in a longterm study of social conventions in wild whitefaced capuchin monkeys, involving examination of a 19,000hour combined data set collected on 13 social groups at four study sites in Costa Rica over a 13year period. Five behavior patterns qualified as social traditions, according to the studys criteria: handsniffing, sucking of body parts, and three types of games. Some conventions were independently invented in virtually identical form at multiple sites. The extinction of several conventions was observed during the course of the study; it appears that they rarely last longer than ten years. It is hypothesized that the monkeys are using these group or cliquespecific social conventions to test the quality of their social relationships.

Kin-biased social behaviour in wild adult female white-faced capuchins, Cebus capucinus

*Department of Anthropology and Center for Behavior, Evolution and Culture,University of California, Los AngelesyMax Planck Institute for Evolutionary AnthropologyzDepartment of Psychology, Indiana University(Received 16 October 2007; initial acceptance 30 October 2007;final acceptance 4 January 2008; published online 27 May 2008; MS. number: A10889R)Studies of kin bias in the distribution of social behaviour in group-living matrifocal species generallyunderline the importance of bonds among female kin. However, few studies examine either how kinbias may be affected by variation in the availability of kin or the relevance of paternal kin. In this study,we used genetic and behavioural data to analyse correlates of coalition formation, proximity, groomingand dominance relations among female white-faced capuchins over a 10-year period during which thenumber of adult females in the group varied from 6 to 10. Females sided with the most closely relatedof two opponents when joining coalitions. Both dominance rank and kinship influenced proximity andgrooming patterns. In particular, when group size was small, mean relatedness high and interdyadic var-iation in relatedness low, rank distance was a better predictor of proximity and grooming than was kinshipdistance. However, when group size was large, mean relatedness lower and interdyadic variation in relat-edness higher, females significantly biased their grooming and spatial proximity towards kin. Dominancerank was not so tightly associated with relatedness as in provisioned female-bonded cercopithecines;females did not follow the ‘youngest sister ascendancy rule’. Full sisters, maternal half sisters andmotheredaughter dyads associated at statistically indistinguishable rates, and all associated significantlymore often than paternal half sisters. Paternal half sisters did not associate more often than distantlyrelated femaleefemale dyads (r < 0.125). These and similar results call into question the general impor-tance of paternal kin ties in wild primates.

Male dominance and reproductive success in wild white-faced capuchins (Cebus capucinus) at Lomas Barbudal, Costa Rica.

Theory and a growing body of empirical evidence suggest that higher ranking males experience reproductive advantages in group‐living mammals. White‐faced capuchins (Cebus capucinus) exhibit an interesting social system for investigating the relationship between dominance and reproductive success (RS) because they live in multimale multifemale social groups, in which the alpha males can have extraordinarily long tenures (i.e. they coreside with daughters of reproductive age). Genetic paternity was determined from fecal samples for 120 infants born into three social groups of wild C. capucinus at Lomas Barbudal Biological Reserve, Costa Rica. Alpha males produced far more offspring than expected by chance, and significantly high Nonacs B indices (a measure of deviation from a random distribution of RS among potentially breeding individuals) were a feature of six out of eight male tenures. The likelihood of the alpha male siring a particular offspring was predicted by the kin relationship between the mother and the alpha male, as well as the total number of males and females in the group. The almost complete lack of father–daughter inbreeding [Muniz et al., 2006] constitutes an impediment to alpha male reproductive monopolization in this population, particularly toward the end of long alpha male tenures. Am. J. Primatol. 72:1118–1130, 2010.

Vocal Repertoire of Cebus capucinus: Acoustic Structure, Context, and Usage

Researchers studying nonhuman primate vocal repertoires suggest that convergent environmental, social, and motivational factors account for intra- and interspecific vocal variation. We provide a detailed overview of the vocal repertoire of white-faced capuchins, including acoustic analyses and contextual information of vocal production and vocal usage by different age-sex classes in social interactions. The repertoire is a mixture of graded and discrete vocalizations. In addition, there is general support for structural variation in vocalizations with changes in arousal level. We also identified several combined vocalizations, which might represent variable underlying motivations. Lastly, by including data on the social contexts and production of vocalizations by different age-sex classes, we provide preliminary information about the function of vocalizations in social interactions for individuals of different rank, age, and sex. Future studies are necessary to explore the function of combined vocalizations and how the social function of vocalizations relate to their acoustic structure, because social use of vocalizations may play an important role in shaping vocal evolution.

Infants' prelinguistic communicative acts and maternal responses: Relations to linguistic development

Infant–parent interactions are bidirectional; therefore, it is important to understand how infants’ communicative behavior elicits variable responses from caregivers and, in turn, how infants’ behavior varies with caregivers’ responses; furthermore, how these moment-to-moment interactive behaviors relate to later language development. The current study addressed these concerns by observing 10- to 13-month-old infants’ interactions with their mothers and measuring their language outcomes when they were 15 months old. The main results were: (1) infants were more likely to combine vocalizations with pointing when mothers were not looking at the target of the point, and when mothers did not respond about the target of the point; (2) infants’ combination of vocalization and pointing behavior, especially those produced when mothers were not attending to the target object of the point, related to infants’ comprehension skills at 15 months as measured by the MacArthur Communicative Development Inventory (MCDI); (3) maternal follow-in responses were related to infants’ improvement in their comprehension and production scores on the MCDI. These results suggest that infants’ own prelinguistic communicative acts that are produced differentially as a function of maternal attention and responses, and the maternal responses that they elicit, contribute to infants’ subsequent language development.

Twelve-month-olds’ vocal production during pointing in naturalistic interactions: Sensitivity to parents’ attention and responses

There have been many rich, naturalistic studies documenting prelinguistic communicative abilities that suggest that the ntegration of alternating eye gaze, vocal behaviors, and nonverbal gestures are indicative of intentional communication (e.g., ates, Camaioni, & Volterra, 1975; Bates, Benigni, Bretherton, Camaioni, & Volterra, 1979; Dore, 1974; Ninio & Bruner, 1978; revarthen & Hubley, 1978). Many observational studies have noted the increase in pointing and concurrent vocalizations rom the age of 12 months into the 2nd year, primarily during the acquisition of first words and later language abilities e.g., Bakeman & Adamson, 1986; Butcher & Goldin-Meadow, 2000; Carpenter et al., 1998; Goldin-Meadow, 1998; Masur, 983; Murphy, 1977); however, some studies have also documented gestures with concurrent prelinguistic vocalizations in ommunicative interactions prior to the acquisition of first words (Bates, 1976; Franco & Butterworth, 1996; Leroy, Mathiot, Morgenstern, 2009; Messinger & Fogel, 1998). Although there are many studies that document gestures and co-occurring ocalizations, few have examined the potential intentional use of communicative behaviors, particularly vocalizations, in ocial interactions (but see Camaioni, 1992; Franco & Butterworth, 1996). There has been an increase in research to investigate whether infants point with the intent to communicate or not. esearchers suggest that infants point initially for the self, without communicative intent, yet parents respond to infants’ ointing as if it was communicative (Carpendale & Lewis, 2004; see also Iverson & Thal, 1998). Similarly, researchers have uggested that communicative pointing may emerge out of initially non-communicative pointing and can be identified ased on whether or not infants alternate eye gaze to their parent and a target when they point versus pointing without ye gaze alternation (Desrochers, Morissette, & Ricard, 1995; Franco & Butterworth, 1996). Recent experimental studies in hich a social partner’s attention and response to an infant’s point are manipulated have helped to reveal the behaviors hat are indicative of communicative pointing. For example, when adults did not share infants’ interests or misidentified heir interests, infants pointed repeatedly and looked at adults more compared to when adults responded with interest and

Acoustic Analysis and Contextual Description of Food-Associated Calls in White-Faced Capuchin Monkeys (Cebus capucinus)

Since early studies of primates that identified vocalizations that attracted others to a food source, the assumed function of food-associated calls has been to inform others of the presence of food. The label food-associated calls and its implied function has led to a focus in research on many species of the costs/benefits for the signaler and recipient of informing others about the presence of food; however, without clearly identifying the calls contextually or acoustically, it is unclear if calls are specific to a feeding context and thus whether calls provide specific information about the presence of food. If calls occur exclusively in the context of feeding, information about individual identity would allow listeners to decide whether or not to approach a calling individual. I conducted acoustic and contextual analyses on food-associated calls in white-faced capuchins. I identified the calls as distinct vocalizations that occur almost exclusively in a feeding context. Discriminant function analyses demonstrate that information about caller sex and identity are encoded in the calls. Therefore, there is the potential for individuals to use acoustic information when responding to food-associated calls; however, playback experiments are necessary to test more explicitly the hypothesis that recipients are able to recognize the calls of specific individuals.

The Influence of Interactive Context on Prelinguistic Vocalizations and Maternal Responses

ABSTRACT Many studies have documented influences of maternal responsiveness on cognitive and language development. Given the bidirectionality of interactions in caregiver-infant dyads, it is important to understand how infant behavior elicits variable responses. Prior studies have shown that mothers respond differentially to features of prelinguistic vocalizations that reflect phonological complexity; however, studies have also found that maternal responses vary as a function of interactive contexts. Thus, it is important to examine how infant phonological features and social context interact to influence maternal responsiveness because language development occurs in social interactions and moment-to-moment behaviors influence development. In the current study, we examined how maternal responses vary relative to infant vocal production and interactional context: puppet play, toy play, and book reading. Infants produced more syllable-like, consonant-vowels (CV) than vowel-like sounds (V) during book reading. Mothers responded to proportionally more CV vocalizations during book reading and puppet play than during toy play; however, it was only during book reading that mothers responded to CV sounds more than V sounds. Overall, mothers responded to CV sounds with imitations/expansions significantly more than other response types. Examining responses within contexts, however, acknowledgments were the most frequent response type, with naming responses during book reading and questions in the puppet context also occurring frequently. Therefore, maternal responses varied relative to both vocal characteristics and context, suggesting key variables in social interactions that may support language development.

Do juvenile males affect adult males' reproductive success in brown-headed cowbirds (Molothrus ater)?

The present study was motivated by a recent anomalous finding between individual competitive performance and reproductive output in brown-headed cowbirds (Molothrus ater). White et al. (2002c) found that adult males who were housed with juveniles outcompeted adults who were housed with other adults when they were brought together to compete for mating opportunities. Although the males in groups that contained both juveniles and adults appeared to be better in securing reproductive opportunities, these groups were found to produce fewer eggs than groups with all adult males (White et al., 2002c). Because adult males were housed with juveniles, it was unclear whether the lower egg production was simply due to juveniles not reproducing or whether the adult males suffered decreased reproductive output. Is the presence of juvenile males advantageous to adult males or do they suffer reproductive consequences? In the current study, we studied four groups of captive cowbirds that differed only in the presence of juvenile males to determine what influence juvenile males have on adult male reproduction. At the end of the breeding season, we performed microsatellite parentage analysis on these four groups. Females in the two groups that contained juvenile and adult males produced fewer fertile eggs compared to females in the all-adult male aviaries. Furthermore, parentage analysis revealed that female reproductive patterns were similar in the two conditions, but females in the juvenile-adult aviaries produced fewer fertile eggs. Similarly, the males in the juvenile-adult aviaries showed a similar pattern of reproductive success as the males in the all-adult male aviaries, but had consistently lower reproductive output.

How Joint Attention Relates to Cooperation in 1- and 2-Year-Olds.

Joint attention has been suggested to contribute to children’s development of cooperation; however, few empirical studies have directly tested this hypothesis. Children aged 1 and 2 years participated in two joint action activities to assess their cooperation with an adult partner, who stopped participating at a specific moment during the tasks. Children’s joint attention skills were measured by the Early Social Communication Scales (ESCS). Results showed that children’s responding to joint attention ability contributed to their successful cooperation in an activity that required parallel roles, whereas initiating joint attention ability contributed to their successful cooperation in an activity that required complementary roles. These results suggest a complex relationship between joint attention and cooperative abilities when considering RJA and IJA separately.