This study investigates a possible nexus between inter-group competition and intra-group cooperation, which may be called "tribalism." Building upon previous studies demonstrating a relationship between the environment and social relations, the present research incorporates a social-ecological model as a mediating factor connecting both individuals and communities to the environment. Cyclical and non-cyclical fluctuation in a simple, two-resource ecology drive agents to adopt either "go-it-alone" or group-based survival strategies via evolutionary selection. Novelly, this simulation employs a multilevel selection model allowing group-level dynamics to exert downward selective pressures on individuals' propensity to cooperate within groups. Results suggest that cooperation and inter-group conflict are co-evolved in a triadic relationship with the environment. Resource scarcity increases inter-group competition, especially when resources are clustered as opposed to widely distributed. Moreover, the tactical advantage of cooperation in the securing of clustered resources enhanced selective pressure on cooperation, even if that implies increased individual mortality for the most altruistic warriors. Troubling, these results suggest that extreme weather, possibly as a result of climate change, could exacerbate conflict in sensitive, weather-dependent social-ecologies---especially places like the Horn of Africa where ecologically sensitive economic modalities overlap with high-levels of diversity and the wide-availability of small arms. As well, global development and foreign aid strategists should consider how plans may increase the value of particular locations where community resources are built or aid is distributed, potentially instigating tribal conflict. In sum, these factors, interacting with pre-existing social dynamics dynamics, may heighten inter-ethnic or tribal conflict in pluralistic but otherwise peaceful communities.

中文翻译：

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部落主义的演变：牧民主义下合作与群体间冲突的社会生态模型

这项研究调查了群体间竞争与群体内合作之间可能存在的联系，这种联系可能被称为“部落主义”。在先前的研究表明环境与社会关系之间的关系的基础上，本研究纳入了社会生态模型作为将个人和社区与环境联系起来的中介因素。简单的，具有两种资源的生态驱动因子中的周期性和非周期性波动可通过进化选择采用“独自行动”或基于群体的生存策略。新颖的是，该模拟采用了多级选择模型，该模型允许组级动态对个人在组内进行协作的倾向施加向下的选择压力。结果表明，合作和群体间冲突在与环境的三元关系中共同发展。资源稀缺性加剧了群体间的竞争，尤其是在资源聚集而不是广泛分布的情况下。此外，合作在确保集群资源方面的战术优势增加了合作的选择性压力，即使这意味着最利他的战士的个人死亡率也会增加。令人不安的是，这些结果表明，可能是气候变化的结果，极端天气可能加剧敏感的，依赖天气的社会生态系统中的冲突，尤其是在非洲之角等对生态敏感的经济模式与高水平的经济重叠的地方。多样性和小型武器的广泛使用。还有 全球发展和外国援助战略家应考虑计划如何增加社区资源建立或分配的特定地点的价值，从而可能引发部落冲突。总而言之，这些因素与先前存在的社会动力相互作用，可能加剧多元化但和平的社区之间的族裔或部落冲突。