Data from: A life-cycle model of human social groups produces a u-shaped distribution in group size

One of the central puzzles in the study of sociocultural evolution is how and why transitions from small-scale human groups to large-scale, hierarchically more complex ones occurred. Here we develop a spatially explicit agent-based model as a first step towards understanding the ecological dynamics of small and large-scale human groups. By analogy with the interactions between single-celled and multicellular organisms, we build a theory of group lifecycles as an emergent property of single cell demographic and expansion behaviours. We find that once the transition from small-scale to large-scale groups occurs, a few large-scale groups continue expanding while small-scale groups gradually become scarcer, and large-scale groups become larger in size and fewer in number over time. Demographic and expansion behaviours of groups are largely influenced by the distribution and availability of resources. Our results conform to a pattern of human political change in which religions and nation states come to be represented by a few large units and many smaller ones. Future enhancements of the model should include decision-making rules and probabilities of fragmentation for large-scale societies. We suggest that the synthesis of population ecology and social evolution will generate increasingly plausible models of human group dynamics.

社会文化演化研究中的核心谜题之一，便是人类群体如何且为何会从小规模社群，转型为层级结构更复杂的大规模社群。
本研究构建了空间显式基于智能体模型（spatially explicit agent-based model），作为理解人类大小社群生态动力学的初步尝试。我们以单细胞生物与多细胞生物的相互作用为类比，提出了一套群体生命周期理论，将群体生命周期视作单个个体人口统计行为与扩张行为的涌现属性。
研究结果显示，一旦完成从小规模社群到大规模社群的转型，少数大规模群体会持续扩张，而小规模社群则逐渐减少；随着时间推移，大规模社群的规模不断扩大，其数量却愈发稀少。群体的人口统计行为与扩张行为，在很大程度上受资源分布与可获得性的影响。
本研究结果契合人类政治变迁的典型模式：宗教与民族国家最终演化为少数大型单元与多数小型单元并存的格局。未来对该模型的改进，应纳入大型社群的决策规则与解体概率等要素。我们认为，将种群生态学与社会演化理论相结合，将能够构建出愈发贴合现实的人类群体动力学模型。