The effects of demography and migration on cooperation and competition: a large-scale field study

在进化科学中，合作被定义为以牺牲行为者为代价造福他人的行为，是人类社会组织的基石。合作的程度和规模在不同人群中有很大差异，许多作者将这种差异归因于文化差异。然而，目前还不清楚是什么驱动了这种文化差异。进化生物学的大量理论预测，人口的人口特征，如人口规模和迁移模式，可能是合作和竞争的重要驱动力。但这些理论观点从未在人类群体中进行过实证检验，因此，进化模型是否是解释人类合作模式变化的有用工具仍不清楚。这项研究将是第一个实证测试这些想法在一组现实世界的人口，以调查人口对合作和竞争的影响是否解释了在人群中观察到的文化差异。这项研究将产生一个大规模的，纵向的行为数据集的合作行为在两个小规模的印度社会的多个人口与对比制度的婚姻和财富继承。将经济博弈、行为调查和对公共工程贡献的观察相结合，来衡量一个母系社会中多个群体的合作水平。（梅加拉亚的卡西人），在那里，典型的男性是迁徙的性别，财富是通过女性血统传递的，以及一个父系社会（恰蒂斯加尔的帕哈里科尔瓦），在那里，女性是迁徙的性别，财富是通过男性血统传递的。这些数据将用于检验这两个社会中带有性别偏见的移徙的对比模式是否影响到社交网络以及两性内部和两性之间的合作水平。通过对每个社会的多个群体的行为进行抽样，我们将能够梳理出移民模式（男性或女性偏见）与移民率在多大程度上驱动了行为;这种抽样策略还将使我们能够调查移民如何与人口的其他人口特征（如人口规模和年龄结构）相互作用，以影响个人的行为。最后，我们将监测研究人群随着时间的推移，即纵向，以检查个人如何修改他们的行为与不断变化的人口模式;这将使我们能够评估人口统计过程和合作之间的关系是否稳定。这项研究还将解决社会科学和自然科学中一个悬而未决的重大问题，即是否存在“合作”和“不合作”类型的人，或者个人是否根据背景改变合作水平。这将通过纵向比较不同措施（经济游戏、自我报告的调查、对公共工程捐款的观察）的个人行为来完成，以测试不同措施之间的任何观察到的相关性（或缺乏相关性）是否随着时间的推移而稳定。该研究报告特别具有专题性，因为它涉及关于移徙对社会结构和社会凝聚力的影响的辩论。这项研究的结果将对管理一系列公共产品的政策制定者感兴趣，包括在英国和国际上共享土地，水和能源资源以及灾害管理和社区建设计划。英国有越来越多来自不同文化背景的移民。通过研究移徙如何影响不同文化群体的社交网络，该项目将及时解决我们需要在移徙者和非移徙者之间建立何种联系的问题，以便改善后者的融合，并在一个多文化社会中保持合作。

Cooperation, defined in the evolutionary sciences as behavior that benefits others at a cost to the actor, is a cornerstone of human social organization. The degree and scale of cooperation varies considerably across human populations and many authors have attributed this variation to cultural differences. However, it remains unclear what drives this cultural variation. A substantial body of theory in evolutionary biology predicts that demographic characteristics of populations, such as their size and patterns of migration, may be important drivers of cooperation and competition. But these theoretical ideas have never been empirically tested in human populations, so it remains unclear whether evolutionary models are useful tools to explain variation in patterns of human cooperation. This study will be the first to empirically test these ideas in a set of real-world populations in order to investigate whether demographic influences on cooperation and competition explain the cultural variation observed across populations.The study will generate a large-scale, longitudinal behavioural dataset of cooperative behavior in multiple populations of two small-scale Indian societies with contrasting systems of marriage and wealth inheritance. A combination of economic games, behavioural surveys, and observations of contributions to public works will be used to measure levels of cooperation in multiple populations of a matrilocal society (the Khasi of Meghalaya), where typically men are the migrating sex and wealth is transmitted via the female line, and a patrilocal society (the Pahari Korwa of Chhattisgarh), where women are the migrating sex and wealth is transmitted via the male line. These data will be used to test whether the contrasting patterns of sex-biased migration in these two societies affect the social networks and levels of cooperation within and between the sexes. By sampling behavior in multiple populations from each society we will be able to tease apart the extent to which behavior is driven by the pattern of migration (male- or female-biased) versus the rate of migration; this sampling strategy will also allow us to investigate how migration interacts with other demographic features of a population, such as its size and age-structure, to affect the behavior of individuals. Finally, we will monitor the study populations over time, i.e. longitudinally, in order to examine how individuals modify their behavior with changing demographic patterns; this will allow us to assess whether the relationships between demographic processes and cooperation are stable. The study will also address a major outstanding question in both the social and natural sciences about whether there are "cooperative" and "non-cooperative" types of people, or whether individuals modify levels of cooperation according to context. This will be done by comparing individuals' behaviour across different measures (economic games, self-reported surveys, observation of contributions to public works) longitudinally to test whether any observed correlations between the different measures (or lack thereof) are stable over time. The study is particularly topical as it addresses debates about the effects of migration on the social structure and cohesion of societies. Findings from this research will be of interest to policy makers managing a range of public goods including shared land, water and energy resources as well as disaster-management and community-building programmes, both in the UK and internationally. The UK has a growing community of immigrants from many different cultural backgrounds. By examining how migration affects the social networks of different cultural groups, the project will address timely questions about the types of links that we need to build between migrants and non-migrants in order to improve the integration of the latter and maintain cooperation in a multi-cultural society.