The scaling laws of human travel
The scaling laws of human travel
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DOI：
10.1038/nature04292
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发表时间：
2006-01-26
期刊：
影响因子：
64.8
通讯作者：
Geisel, T
中科院分区：
文献类型：
--
作者：
Brockmann, D;Hufnagel, L;Geisel, T
个体的动态空间再分布是地理尺度上各种时空现象的关键驱动力。它可以同步相互作用的物种种群，稳定它们，并使基因库多样化（1-3）。例如，人类旅行是人类传染病地理传播的原因（4-9）。鉴于国际贸易不断增加，人类流动性增强以及甲型流感流行的迫在眉睫的威胁（10），人类旅行的动态和统计特性的知识具有根本的重要性。尽管它的关键作用，在地理尺度上的这些属性的定量评估仍然是难以捉摸的，和假设，人类扩散仍然盛行的模型。在这里，我们通过分析美国的钞票流通情况，对人类旅行统计数据进行了可靠的定量评估。使用一个全面的数据集超过一百万个人的位移，我们发现，分散是异常的两种方式。首先，旅行距离的分布衰减为幂律，这表明钞票的轨迹让人想起被称为Levy飞行的无标度随机行走。第二，在一个小的，空间受限的区域内的时间T的概率是由代数长尾，衰减超扩散蔓延占主导地位。我们表明，人类的旅行行为可以在许多时空尺度上的数学描述的两个参数的连续时间随机游走模型的一个令人惊讶的准确性，并得出结论，人类旅行的地理尺度上是一个矛盾的，有效的超扩散过程。
The dynamic spatial redistribution of individuals is a key driving force of various spatiotemporal phenomena on geographical scales. It can synchronize populations of interacting species, stabilize them, and diversify gene pools(1-3). Human travel, for example, is responsible for the geographical spread of human infectious disease(4-9). In the light of increasing international trade, intensified human mobility and the imminent threat of an influenza A epidemic(10), the knowledge of dynamical and statistical properties of human travel is of fundamental importance. Despite its crucial role, a quantitative assessment of these properties on geographical scales remains elusive, and the assumption that humans disperse diffusively still prevails in models. Here we report on a solid and quantitative assessment of human travelling statistics by analysing the circulation of bank notes in the United States. Using a comprehensive data set of over a million individual displacements, we find that dispersal is anomalous in two ways. First, the distribution of travelling distances decays as a power law, indicating that trajectories of bank notes are reminiscent of scale-free random walks known as Levy flights. Second, the probability of remaining in a small, spatially confined region for a time T is dominated by algebraically long tails that attenuate the superdiffusive spread. We show that human travelling behaviour can be described mathematically on many spatiotemporal scales by a two-parameter continuous-time random walk model to a surprising accuracy, and conclude that human travel on geographical scales is an ambivalent and effectively superdiffusive process.