聚落遗址迁移最优路径模拟

古遗址作为古人生产、生活的重要场所和文化遗存,客观反映了在长期的人地关系相互作用下的地理空间特征及其分异情况,但是由于史前人类生产力水平低下,在聚落迁移或对周边资源探索中更多地考虑自然环境因素,这种行为符合“最优路径”的思想。本文旨在基于考古调查和基础地理数据,模拟构建古人在聚落选择上的迁移最优路径,探讨古人行为模式,重点研究成本数据确定和成本栅格数据的集成方法及最优路径应用分析。以长江中游新石器晚期的大溪文化、屈家岭文化、石家河文化为连续研究文化期,对其中1200多处遗址的基础地理数据和考古数据进行分析;选取高程、坡度/坡向、地形起伏度、距水系距离等自变量,基于二分类逻辑回归模型,构建研究区史前聚落遗址分布模型。为分析聚落群的时空演变,首先基于期望最大化方法（EM算法）和Voronoi方法对聚落遗址数据进行聚类划分聚落群的中心点的确定,选取分布模型中的自然因子系数作为权重计算成本栅格数据,进而模拟聚落遗址按时序迁移的最优路径。研究结果符合古人类在迁移过程中多考虑以最低成本从山谷、丘陵中穿行的基本规律。并对比已探明的聚落遗址信息,验证模拟的最优路径具有一定的合理性。本文提出的方法,避免了人为选择权重生成成本栅格所带来的仅依靠主观因素的局限,提高了考古研究的科学性,其研究方法和结论对于探究史前聚落遗址时空演变规律和人地关系有一定的参考价值。

Simulating the Optimal Migration Paths between Prehistoric Settlement Sites

As the relics of the ancients for production and other activities, prehistoric settlement sites reflected objectively the strong geographical features and differentiation patterns of long-term human-environment interactions. Due to the low productivity of the ancients, more natural factors were likely taken into account in between-settlement migration and resource exploration around their residences, which was consistent with the idea of "optimal path." This paper aimed to simulate the optimal path of the ancients in migrating between settlement sites, and to explore their behavioral pattern based on archaeological and geographic data. We emphasized the determination of migration cost, the integration of cost raster layers, and the optimal path analysis. The basic geographical and archaeological data of more than 1200 sites of the sequential cultural period, involving Daxi, Qujialing, and Shijiahe Cultures in the late Neolithic period in the middle reaches of the Yangtze River, were included for this study. Elevation, slope/slope direction, topographical relief, and distance from water were selected as the independent variables to analyze and construct the distribution model of the settlement sites in the study area, based on binary classification logistic regression model. To analyze the spatiotemporal evolution of the settlement groups, firstly, the clustering and centers of the settlement groups were identified based on the Expectation Maximization method and Voronoi algorithm; then, the natural factor coefficients in the distribution model were used as weights to generate the cost raster layers; lastly, the layers were input for simulating the optimal path of between-settlement migration constructed based on the cultural sequence. The results were consistent with the basic rule that the ancients were inclined to walk through valleys and hills in the process of migration at the lowest cost. The simulated path was proved reasonable when compared to the other available site information. The method proposed in this paper can address the limitation of relying on only subjective weighting in generating and integrating the cost raster layers, and can enhance the science of archaeological research. Our method and conclusion help explore the spatiotemporal evolution patterns of prehistoric settlement sites and human-environment relationship.