Global Patterns of City Size Distributions and Their Fundamental Drivers

Urban areas and their voracious appetites are increasingly dominating the flows of energy and materials around the globe. Understanding the size distribution and dynamics of urban areas is vital if we are to manage their growth and mitigate their negative impacts on global ecosystems. For over 50 years, city size distributions have been assumed to universally follow a power function, and many theories have been put forth to explain what has become known as Zipf's law (the instance where the exponent of the power function equals unity). Most previous studies, however, only include the largest cities that comprise the tail of the distribution. Here we show that national, regional and continental city size distributions, whether based on census data or inferred from cluster areas of remotely-sensed nighttime lights, are in fact lognormally distributed through the majority of cities and only approach power functions for the largest cities in the distribution tails. To explore generating processes, we use a simple model incorporating only two basic human dynamics, migration and reproduction, that nonetheless generates distributions very similar to those found empirically. Our results suggest that macroscopic patterns of human settlements may be far more constrained by fundamental ecological principles than more fine-scale socioeconomic factors

A civilização maia: contextualização historiográfica e arqueológica The Mayan Civilization: historiographic and archeological contextualization

Este artigo versa sobre a contextualização historiográfica e arqueológica da civilização maia. O intuito é traçar um perfil das primeiras explorações nos sítios arqueológicos, observar a construção do conhecimento criada acerca das primeiras informações obtidas pela Arqueologia, além das diversas vinculações das pesquisas empreendidas em relação aos contextos históricos de sua época e as teorias utilizadas atualmente pelos maístas.<br>This article deals with the historiographic and archeological contextualization of the Mayan civilization. Its purpose is to trace the profile of the first explorations into archeological sites, the construction of the knowledge created around the first information obtained by Archeology, as well as the diverse research links undertaken in relation to the historical contexts of its time, and the theories used at present by the Mayanists