• Are men funnier than women, or do we just think they are?

      Hooper, Jade; Sharpe, Donald; Roberts, Sam G. B.; University of Chester (2016-03)
      Despite the widely held view that men are funnier than women, research supporting this view is inconsistent. Instead, the view that men are funnier than women may be a stereotype rather than a reflection of real differences in humor. Considering a previously found source memory bias in the attribution of funnier captions to men and less funny captions to women, this stereotype may be working to further perpetuate this mistaken belief. The current study aims to investigate this possible stereotype and further investigate an attribution bias arising from this stereotype. Two-hundred and twenty-eight participants from three countries (Britain, Canada, and Australia) rated the funniness of male and female-authored cartoon captions while blind to the gender of the caption authors. Participants were then asked to guess the gender of the caption authors and were also asked which gender they believe to be the funniest. Participants both male and female believed men are the funniest gender. However, this belief was not reflected in their ratings of the funniness of the cartoon captions. Support was found for a bias in attributing male authorship to the funniest cartoon captions, and female authorship to the least funny cartoon captions. This bias cannot not be attributed to source memory. It was suggested this stereotype may be self-fulfilling in nature and additional mechanisms maintaining this stereotype are proposed.
    • Channel-specific daily patterns in mobile communication

      Aledavood, Talayeh; Lopez, Eduardo; Roberts, Sam G. B.; Reed-Tsochas, Felix; Moro, Esteban; Dunbar, Robin I. M.; Saramäki, Jari; University of Chester (Springer International Publishing, 2016-05)
      Humans follow circadian rhythms, visible in their activity levels as well as physiological and psychological factors. Such rhythms are also visible in electronic communication records, where the aggregated activity levels of e.g. mobile telephone calls or Wikipedia edits are known to follow their own daily patterns. Here, we study the daily communication patterns of 24 individuals over 18 months, and show each individual has a different, persistent communication pattern. These patterns may differ for calls and text messages, which points towards calls and texts serving a different role in communication. For both calls and texts, evenings play a special role. There are also differences in the daily patterns of males and females both for calls and texts, both in how they communicate with individuals of the same gender vs. opposite gender, and also in how communication is allocated at social ties of different nature (kin ties vs. non-kin ties). Taken together, our results show that there is an unexpected richness to the daily communication patterns, from different types of ties being activated at different times of day to different roles of channels and gender differences.
    • Chimpanzees modify intentional gestures to coordinate a search for hidden food

      Roberts, Anna I.; Vick, Sarah-Jane; Roberts, Sam G. B.; Menzel, Charles R.; University of Chester; University of Stirling; Georgia State University (Nature Publishing Group, 2014-01-16)
      Humans routinely communicate to coordinate their activities, persisting and elaborating signals to pursue goals that cannot be accomplished individually. Communicative persistence is associated with complex cognitive skills such as intentionality, because interactants modify their communication in response to another’s understanding of their meaning. Here we show that two language-trained chimpanzees effectively use intentional gestures to coordinate with an experimentally naive human to retrieve hidden food, providing some of the most compelling evidence to date for the role of communicative flexibility in successful coordination in nonhumans. Both chimpanzees (named Panzee and Sherman) increase the rate of non-indicative gestures when the experimenter approaches the location of the hidden food. Panzee also elaborates her gestures in relation to the experimenter’s pointing, which enables her to find food more effectively than Sherman. Communicative persistence facilitates effective communication during behavioural coordination and is likely to have been important in shaping language evolution.
    • Close social relationships: An evolutionary perspective

      Roberts, Sam G. B.; Arrow, Holly; Gowlett, John A. J.; Lehmann, Julia; Dunbar, Robin I. M.; University of Chester (Oxford University Press, 2014-02-06)
      This review provides an evolutionary perspective on close social relationships. We focus on three core issues: their function, their number and quality, and their maintenance. Our aim is not to provide a unified theory of relationships, but rather to synthesize evidence from social psychology, evolutionary theory, ethology, anthropology, and sociology in an attempt to develop a more integrated approach. For these purposes, we focus on three different types of social bonds: mateships, kinship bonds, and friendships.
    • Communicative roots of complex sociality and cognition.

      Roberts, Anna I.; Roberts, Sam G. B. (2019-10-14)
      Mammals living in more complex social groups typically have large brains for their body size and many researchers have proposed that the primary driver of the increase in brain size through primate and hominin evolution was the selection pressures associated with sociality. Many mammals, and especially primates, use flexible signals that show a high degree of voluntary control and these signals may play an important role in forming and maintaining social relationships between group members. However, the specific role that cognitive skills play in this complex communication, and how in turn this relates to sociality, is still unclear. The hypothesis for the communicative roots of complex sociality and cognition posits that cognitive demands behind the communication needed to form and maintain bonded social relationships in complex social settings drives the link between brain size and sociality. We review the evidence in support of this hypothesis and why key features of cognitively complex communication such as intentionality and referentiality should be more effective in forming and maintaining bonded relationships as compared with less cognitively complex communication. Exploring the link between cognition, communication and sociality provides insights into how increasing flexibility in communication can facilitate the emergence of social systems characterised by bonded social relationships, such as those found in non-human primates and humans. To move the field forward and carry out both within- and among-species comparisons, we advocate the use of social network analysis, which provides a novel way to describe and compare social structure. Using this approach can lead to a new, systematic way of examining social and communicative complexity across species, something that is lacking in current comparative studies of social structure. [Abstract copyright: © 2019 Cambridge Philosophical Society.]
    • Complex Sociality of Wild Chimpanzees Can Emerge from Laterality of Manual Gestures.

      Roberts, Anna I.; Murray, Lindsay; Roberts, Sam G. B. (Springer, 2019-06-24)
      Humans are strongly lateralized for manual gestures at both individual and population levels. In contrast, the laterality bias in primates is less strong, leading some to suggest that lateralization evolved after the Pan and Homo lineages diverged. However, laterality in humans is also context-dependent, suggesting that observed differences in lateralization between primates and humans may be related to external factors such as the complexity of the social environment. Here we address this question in wild chimpanzees and examine the extent to which the laterality of manual gestures is associated with social complexity. Right-handed gestures were more strongly associated with goal-directed communication such as repair through elaboration in response to communication failure than left-handed gestures. Right-handed gestures occurred in evolutionarily urgent contexts such as in interactions with central individuals in the network, including grooming reciprocity and mating, whereas left-handed gestures occurred in less-urgent contexts, such as travel and play. Right-handed gestures occurred in smaller parties and in the absence of social competition relative to left-handed gestures. Right-handed gestures increased the rate of activities indicating high physiological arousal in the recipient, whereas left-handed gestures reduced it. This shows that right- and left-handed gestures differ in cognitive and social complexity, with right-handed gestures facilitating more complex interactions in simpler social settings, whereas left-handed gestures facilitate more rewarding interactions in complex social settings. Differences in laterality between other primates and humans are likely to be driven by differences in the complexity of both the cognitive skills underpinning social interactions and the social environment.
    • Daily rhythms in mobile telephone communication

      Aledavood, Talayeh; López, Eduardo; Roberts, Sam G. B.; Reed-Tsochas, Felix; Moro, Esteban; Dunbar, Robin I. M.; Saramäki, Jari; Aalto University School of Science; University of Oxford; University of Chester; Universidad Carlos III de Madrid (Public library of Science, 2015-09-21)
      Circadian rhythms are known to be important drivers of human activity and the recent availability of electronic records of human behaviour has provided fine-grained data of temporal patterns of activity on a large scale. Further, questionnaire studies have identified important individual differences in circadian rhythms, with people broadly categorised into morning-like or evening-like individuals. However, little is known about the social aspects of these circadian rhythms, or how they vary across individuals. In this study we use a unique 18-month dataset that combines mobile phone calls and questionnaire data to examine individual differences in the daily rhythms of mobile phone activity. We demonstrate clear individual differences in daily patterns of phone calls, and show that these individual differences are persistent despite a high degree of turnover in the individuals’ social networks. Further, women’s calls were longer than men’s calls, especially during the evening and at night, and these calls were typically focused on a small number of emotionally intense relationships. These results demonstrate that individual differences in circadian rhythms are not just related to broad patterns of morningness and eveningness, but have a strong social component, in directing phone calls to specific individuals at specific times of day.
    • Gestural communication and mating tactics in wild chimpanzees.

      Roberts, Anna I.; Roberts, Sam G. B.; University of Chester (Public Library of Science, 2015-11-04)
      The extent to which primates can flexibly adjust the production of gestural communication according to the presence and visual attention of the audience provides key insights into the social cognition underpinning gestural communication, such as an understanding of third party relationships. Gestures given in a mating context provide an ideal area for examining this flexibility, as frequently the interests of a male signaller, a female recipient and a rival male bystander conflict. Dominant chimpanzee males seek to monopolize matings, but subordinate males may use gestural communication flexibly to achieve matings despite their low rank. Here we show that the production of mating gestures in wild male East African chimpanzees (Pan troglodytes schweunfurthii) was influenced by a conflict of interest with females, which in turn was influenced by the presence and visual attention of rival males. When the conflict of interest was low (the rival male was present and looking away), chimpanzees used visual/ tactile gestures over auditory gestures. However, when the conflict of interest was high (the rival male was absent, or was present and looking at the signaller) chimpanzees used auditory gestures over visual/ tactile gestures. Further, the production of mating gestures was more common when the number of oestrous and non-oestrus females in the party increased, when the female was visually perceptive and when there was no wind. Females played an active role in mating behaviour, approaching for copulations more often when the number of oestrus females in the party increased and when the rival male was absent, or was present and looking away. Examining how social and ecological factors affect mating tactics in primates may thus contribute to understanding the previously unexplained reproductive success of subordinate male chimpanzees.
    • Gestural repertoire size is associated with social proximity measures in wild chimpanzees.

      Roberts, Anna I.; Chakrabarti, Anwesha; Roberts, Sam G. B. (2019-02-01)
      Studying the communication systems of primates can provide insights into the evolutionary origins of human language. Some theories propose that language evolved to help meet the demands of managing complex social relationships. Examining the associations between sociality and communication in the great apes can help to identify the specific selection pressures that may have been important for language evolution. In particular, gestural communication is believed to be important because it is a relatively recent trait seen only in primates and particularly in the great apes. However, the extent to which more complex gestural communication plays a role in managing social relationships, as compared to less complex gestural communication, is not well understood. Using social network analysis, we examined the association between complex gesturing (indexed as repertoire size) and complexity of social relationships indexed as proximity (the duration of time spent within 10 m, per hour spent in same party) in wild chimpanzees (Pan troglodytes schweinfurthii). Repertoire size (the total number of gesture types a focal subject produced toward other individuals) and dyadic repertoire size (the number of gesture types produced toward the dyad partner, per hour spent within 10 meters) were positively associated with proximity at the level of the group (centrality in the proximity network) and the dyad (proximity duration between dyads), respectively. Further, the repertoire size of visual and auditory short-range gestures was positively associated with proximity, while the repertoire size of tactile gesture was negatively associated with proximity. Overall these results suggest that gestural repertoire size has important implications for maintaining social relationships in wild chimpanzees and more broadly that gestural communication may have played an important role in language evolution. [Abstract copyright: © 2019 Wiley Periodicals, Inc.]
    • Managing relationship decay: Network, gender and contextual effects.

      Roberts, Sam G. B.; Dunbar, Robin I. M.; University of Chester; University of Oxford (Springer, 2015-10-21)
      Relationships are central to human life strategies and have crucial fitness consequences. Yet, at the same time, they incur significant maintenance costs that are rarely considered in either social psychological or evolutionary studies. Although many social psychological studies have explored their dynamics, these studies have typically focused on a small number of emotionally intense ties, whereas social networks in fact consist of a large number of ties that serve a variety of different functions. In this study, we examined how entire active personal networks changed over 18 months across a major life transition. Family relationships and friendships differed strikingly in this respect. The decline in friendship quality was mitigated by increased effort invested in the relationship, but with a striking gender difference: relationship decline was prevented most by increased contact frequency (talking together) for females but by doing more activities together in the case of males.
    • Persistence in gestural communication predicts sociality in wild chimpanzees.

      Roberts, Anna I.; Roberts, Sam G. B. (2018-10-19)
      A key challenge for primates is coordinating behaviour with conspecifics in large, complex social groups. Gestures play a key role in this process and chimpanzees show considerable flexibility communicating through single gestures, sequences of gestures interspersed with periods of response waiting (persistence), and rapid sequences where gestures are made in quick succession, too rapid for the response waiting to have occurred. The previous studies examined behavioural reactions to single gestures and sequences, but whether this complexity is associated with more complex sociality at the level of the dyad partner and the group as a whole is not well understood. We used social network analysis to examine how the production of single gestures and sequences of gestures was related to the duration of time spent in proximity and individual differences in proximity in wild East African chimpanzees (Pan troglodytes schweinfurthii). Pairs of chimpanzees that spent a longer duration of time in proximity had higher rates of persistence sequences, but not a higher rate of single gestures or rapid sequences. The duration of time spent in proximity was also related to the rate of responding to gestures, and response to gesture by activity change. These results suggest that communicative persistence and the type of response to gestures may play an important role in regulating social interactions in primate societies.
    • Persistence of social signatures in human communication

      Saramäki, Jari; Leicht, Elizabeth A.; Lopez, Eduardo; Roberts, Sam G. B.; Reed-Tsochas, Felix; Dunbar, Robin I. M.; Aalto University School of Science; University of Oxford; University of Chester (2014-01-06)
      The social network maintained by a focal individual, or ego, is intrinsically dynamic and typically exhibits some turnover in membership over time as personal circumstances change. However, the consequences of such changes on the distribution of an ego’s network ties are not well understood. Here we use a unique 18-mo dataset that combines mobile phone calls and survey data to track changes in the ego networks and communication patterns of students making the transition from school to university or work. Our analysis reveals that individuals display a distinctive and robust social signature, captured by how interactions are distributed across different alters. Notably, for a given ego, these social signatures tend to persist over time, despite considerable turnover in the identity of alters in the ego network. Thus, as new network members are added, some old network members either are replaced or receive fewer calls, preserving the overall distribution of calls across network members. This is likely to reflect the consequences of finite resources such as the time available for communication, the cognitive and emotional effort required to sustain close relationships, and the ability to make emotional investments.
    • The repertoire and intentionality of gestural communication in wild chimpanzees.

      Roberts, Anna I.; Vick, Sarah-Jane; Roberts, Sam G. B.; University of Chester; Budongo Conservation Field Station; University of Stirling (Springer, 2014-09-03)
      A growing body of evidence suggests that human language may have emerged primarily in the gestural rather than vocal domain, and that studying gestural communication in great apes is crucial to understanding language evolution. Although manual and bodily gestures are considered distinct at a neural level, there has been very limited consideration of potential differences at a behavioural level. In this study, we conducted naturalistic observations of adult wild East African chimpanzees (Pan troglodytes schweinfurthii) in order to establish a repertoire of gestures, and examine intentionality of gesture production, use and comprehension, comparing across manual and bodily gestures. At the population level, 120 distinct gesture types were identified, consisting of 65 manual gestures and 55 bodily gestures. Both bodily and manual gestures were used intentionally and effectively to attain specific goals, by signallers who were sensitive to recipient attention. However, manual gestures differed from bodily gestures in terms of communicative persistence, indicating a qualitatively different form of behavioural flexibility in achieving goals. Both repertoire size and frequency of manual gesturing were more affiliative than bodily gestures, while bodily gestures were more antagonistic. These results indicate that manual gestures may have played a significant role in the emergence of increased flexibility in great ape communication and social bonding
    • The Six Dimensions of Personality (HEXACO) and their Associations with Network Layer Size and Emotional Closeness to Network Members

      Molho, Catherine; Roberts, Sam G. B.; de Vries, Reinout; Pollet, Thomas; VU Amsterdam, University of Chester, University of Twente (Elsevier, 2016-05-14)
      Previous work has examined how specific personality dimensions are associated with social network characteristics. However, it is unclear how the full range of personality traits relates to the quantity and quality of relationships at different network layers. This study (N = 525) investigates how the six HEXACO personality dimensions relate to the size of support and sympathy groups, and to the level of emotional closeness to network members. Extraversion was positively related to support group size, but did not significantly relate to sympathy group size or emotional closeness. Openness to Experience and Emotionality were positively related to support group size, but not to the size of the sympathy group. Honesty–Humility, but not Agreeableness, was positively related to emotional closeness to members of the sympathy group. Findings suggest that personality effects vary across network layers and highlight the importance of considering both emotional closeness and network size.
    • Social Brain Hypothesis: Vocal and Gesture Networks of Wild Chimpanzees

      Roberts, Sam G. B.; Roberts, Anna I.; University of Chester (2016-11-24)
      A key driver of brain evolution in primates and humans is the cognitive demands arising from managing social relationships. In primates, grooming plays a key role in maintaining these relationships, but the time that can be devoted to grooming is inherently limited. Communication may act as an additional, more time-efficient bonding mechanism to grooming, but how patterns of communication are related to patterns of sociality is still poorly understood. We used social network analysis to examine the associations between close proximity (duration of time spent within 10m per hour spent in the same party), grooming, vocal communication and gestural communication (duration of time and frequency of behaviour per hour spent within 10 meters) in wild chimpanzees. The results were not corrected for multiple testing. Chimpanzees had differentiated social relationships, with focal chimpanzees maintaining some level of proximity to almost all group members, but directing gestures at and grooming with a smaller number of preferred social partners. Pairs of chimpanzees that had high levels of close proximity had higher rates of grooming. Importantly, higher rates of gestural communication were also positively associated with levels of proximity, and specifically gestures associated with affiliation (greeting, gesture to mutually groom) were related to proximity. Synchronized low-intensity pant-hoots were also positively related to proximity in pairs of chimpanzees. Further, there were differences in the size of individual chimpanzees’ proximity networks - the number of social relationships they maintained with others. Focal chimpanzees with larger proximity networks had a higher rate of both synchronized low- intensity pant-hoots and synchronized high-intensity pant-hoots. These results suggest that in addition to grooming, both gestures and synchronized vocalisations may play key roles in allowing chimpanzees to manage a large and differentiated set of social relationships. Gestures may be important in reducing the aggression arising from being in close proximity to others, allowing for proximity to be maintained for longer and facilitating grooming. Vocalisations may allow chimpanzees to communicate with a larger number of recipients than gestures and the synchronized nature of the pant-hoot calls may facilitate social bonding of more numerous social relationships. As group sizes increased through human evolution, both gestures and synchronized vocalizations may have played important roles in bonding social relationships in a more time-efficient manner than grooming.
    • Wild chimpanzees modify modality of gestures according to the strength of social bonds and personal network size

      Roberts, Anna I.; Roberts, Sam G. B.; University of Chester (Nature Publishing Group, 2016-09-21)
      Primates form strong and enduring social bonds with others and these bonds have important fitness consequences. However, how different types of communication are associated with different types of social bonds is poorly understood. Wild chimpanzees have a large repertoire of gestures, from visual gestures to tactile and auditory gestures. We used social network analysis to examine the association between proximity bonds (time spent in close proximity) and rates of gestural communication in pairs of chimpanzees when the intended recipient was within 10 m of the signaller. Pairs of chimpanzees with strong proximity bonds had higher rates of visual gestures, but lower rates of auditory long-range and tactile gestures. However, individual chimpanzees that had a larger number of proximity bonds had higher rates of auditory and tactile gestures and lower rates of visual gestures. These results suggest that visual gestures may be an efficient way to communicate with a small number of regular interaction partners, but that tactile and auditory gestures may be more effective at communicating with larger numbers of weaker bonds. Increasing flexibility of communication may have played an important role in managing differentiated social relationships in groups of increasing size and complexity in both primate and human evolution.