Growth, innovation, scaling, and the pace of life in cities
Growth, innovation, scaling, and the pace of life in cities
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DOI：
10.1073/pnas.0610172104
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发表时间：
2007-04-24
影响因子：
11.1
通讯作者：
West, Geoffrey B.
中科院分区：
文献类型：
--
作者：
Bettencourt, Luis M. A.;Lobo, Jose;West, Geoffrey B.
人类刚刚跨越了其历史上的一个重要里程碑，大多数人现在生活在城市中。长期以来，城市一直被认为是社会创新和财富创造的主要引擎，但它们也是犯罪、污染和疾病的主要来源。世界范围内城市化的必然趋势对发展城市组织和可持续发展的预测性定量理论提出了紧迫的挑战。在这里，我们提出的经验证据表明，城市化与经济发展和知识创造的过程是非常普遍的，属于同一城市系统的所有城市都有，并在不同的国家和时代持续存在。城市的许多不同属性，从专利生产和个人收入到电缆长度，都是人口规模的幂律函数，其标度指数β属于不同的普适性类。反映财富创造和创新的企业的贝塔系数约为1.2 > 1（收益递增），而基础设施企业的贝塔系数约为0.8 < 1（规模经济）。我们预测，城市中社会生活的节奏随着人口规模的增加而增加，与数据定量一致，我们讨论了城市与生物有机体的相似性和不同之处，其中β < 1。最后，我们通过推导增长方程来探索这些比例关系的可能后果，这些增长方程量化了创新推动的增长与规模经济驱动的增长之间的巨大差异。这种差异表明，随着人口的增长，主要的创新周期必须以不断加快的速度产生，以维持增长，避免停滞或崩溃。
Humanity has just crossed a major landmark in its history with the majority of people now living in cities. Cities have long been known to be society's predominant engine of innovation and wealth creation, yet they are also its main source of crime, pollution, and disease. The inexorable trend toward urbanization worldwide presents an urgent challenge for developing a predictive, quantitative theory of urban organization and sustainable development. Here we present empirical evidence indicating that the processes relating urbanization to economic development and knowledge creation are very general, being shared by all cities belonging to the same urban system and sustained across different nations and times. Many diverse properties of cities from patent production and personal income to electrical cable length are shown to be power law functions of population size with scaling exponents, beta, that fall into distinct universality classes. Quantities reflecting wealth creation and innovation have beta approximate to 1.2 > 1 (increasing returns), whereas those accounting for infrastructure display beta approximate to 0.8 < 1 (economies of scale). We predict that the pace of social life in the city increases with population size, in quantitative agreement with data, and we discuss how cities are similar to, and differ from, biological organisms, for which beta < 1. Finally, we explore possible consequences of these scaling relations by deriving growth equations, which quantify the dramatic difference between growth fueled by innovation versus that driven by economies of scale. This difference suggests that, as population grows, major innovation cycles must be generated at a continually accelerating rate to sustain growth and avoid stagnation or collapse.