Report
Teaser, summary, work performed and final results
Periodic Reporting for period 2 - Outgroup (Consequences of out-group conflict)
Teaser
The aim of this project is to determine the proximate and ultimate consequences of a fundamental but neglected aspect of sociality: out-group conflict. In a wide range of social species, from ants to humans, group members invest considerable defensive effort against individual...
Summary
The aim of this project is to determine the proximate and ultimate consequences of a fundamental but neglected aspect of sociality: out-group conflict. In a wide range of social species, from ants to humans, group members invest considerable defensive effort against individual intruders and rival groups. The lasting impacts of these conflicts with conspecifics are poorly understood. The Outgroup project will integrate empirical and theoretical approaches to uncover the effect of out-group conflict on: (i) individual behaviour, within-group interactions and group decision-making; (ii) steroid hormones that underlie stress, social behaviour and reproduction; (iii) variation in reproductive success arising from maternal investment and offspring care; and (iv) the evolution of societal structure, cooperation and punishment among group-mates, and weaponry and fortification. These these ambitious objectives will be achieved using proven experimental paradigms, innovative non-invasive sampling, long-term monitoring, and state-of-the-art analytical methods to collect data from two highly tractable model systems that have been established over several years: a captive-breeding population of the cichlid fish Neolamprologus pulcher and a habituated wild population of dwarf mongooses (Helogale parvula). Some of the same data will be used to inform the assumptions of mathematical models and evolutionary simulations in the development of a rigorous, predictive framework on out-group conflict, which will be tested using both model systems and phylogenetically controlled meta-analyses across species. The management and consequences of conflict are of major importance to science, human society and global politics. This novel and inter-disciplinary proposal will not only significantly advance our understanding of the evolution of sociality, but will invigorate a variety of existing research programmes across biology, anthropology, economics, psychology, and the social and political sciences.
Work performed
Work has been conducted on all four objectives of the project. Several experiments have been conducted on both the captive cichlid fish population (considering threats from individual outsiders) and the wild dwarf mongoose population (considering threats from rival groups). Short-term experiments (involving single simulations of an outgroup threat) have demonstrated effects on individual behaviour (e.g. increased vigilance, closer proximity when foraging), within-group interactions (e.g. increased affiliation) and group decisions (e.g. movement patterns, choice of sleeping burrow). Moreover, those short-term experiments have shown that the behavioural consequences of outgroup conflict differ depending on the identity of the intruder, the level of threat presented and between group members of different sex and dominance status.The effects of a single simulated intrusion can last for at least an hour in the aftermath and contributions to defensive actions can also influence subsequent within-group interactions. Longer-term experiments, involving repeated simulations of an outgroup threat, have also been conducted on both main study systems. With the cichlids, territorial intrusions were simulated for 12 weeks so that the effect on baseline within-group behaviour, reproductive output (e.g. number of clutches, clutch size, hatching success, fry survival) and parental-care behaviour could be determined (analyses are ongoing). With the wild mongooses, territorial intrusions were simulated over a week so that the effects on baseline individual and within-group behaviour, movement patterns, choice of sleeping burrows, patrolling and latrine-marking could be determined (analyses are ongoing). Faecal samples have been collected from the dwarf mongooses as part of the longer-term experiment, and are currently being analysed for hormonal levels to complement the behavioural data.The long-term dwarf mongoose database (from 2011 and including new data collected as part of the Outgroup project) are being analysed to assess the influence of overall outgroup threat levels (e.g. number of neighbours, rates of intrusions) on reproductive output (number of breeding attempts, number of pups produced, pup weight), movement patterns, parental-care behaviour and parental weight.
With respect to evolutionary consequences, a combination of theoretical modelling and empirical work has been conducted. New analytical models and evolutionary simulations have been used to assess the factors that cause variation in defence contributions by different group members when facing an outgroup threat, how outgroup conflict can influence reproductive skew within groups, the importance of a stochastic world (stochasticity can arise from fluctuations in the social environment) in driving cooperation, and how groups should invest in attack vs defence when faced with outside threats. Empirical work on the dwarf mongooses has considered various aspects of cooperation, including contingent cooperation between group members and cooperative interactions following the immigration of a new group members (one of the potential outcomes of outgroup conflict).
The theoretical and empirical work, along with relevant reviews, have so far generated 10 published peer-review papers, with several others submitted or in preparation. The research team have been invited to give a number of talks and seminars at conferences, workshops and academic institutions, and have contributed to several additional conferences. They have also written popular articles, conducted a number of school visits and ensured that the work from this project has a wide audience on social media.
Final results
Progress has been very good to date and we expect to deliver on all objectives by the end of the project;a substantial number of papers have already been published or are under consideration.
Our work and outputs have attracted much interest from other researchers in biology (including those interested in behavioural ecology, physiology, reproduction, cognition and evolution), as well as psychologists, anthropologists and political scientists. We know of several other research groups now working actively on outgroup conflict as a consequence, and we have been invited to speak at interdisciplinary conferences and workshops given the broad appeal of our project and its findings. The work is also attracting the attention of broader non-academic audiences given the relevant to human conflict at all scales (from mother-toddler groups, to football fans and post-pub confrontations, to nation warfare). Our aim is to make our results as widely available and as applicable as possible.