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Persistent differences in wealth and power among prehispanic Pueblo societies are visible from the late AD 800s through the late 1200s, after which large portions of the northern US Southwest were depopulated. In this paper we measure these differences in wealth using Gini coefficients based on house size, and show that high Ginis (large wealth differences) are positively related to persistence in settlements and inversely related to an annual measure of the size of the unoccupied dry-farming niche. We argue that wealth inequality in this record is due first to processes inherent in village life which have internally different distributions of the most productive maize fields, exacerbated by the dynamics of systems of balanced reciprocity; and second to decreasing ability to escape village life owing to shrinking availability of unoccupied places within the maize dry-farming niche as villages get enmeshed in regional systems of tribute or taxation. We embed this analytical reconstruction in the model of an ‘Abrupt imposition of Malthusian equilibrium in a natural-fertility, agrarian society’ proposed by Puleston et al . (Puleston C, Tuljapurkar S, Winterhalder B. 2014 PLoS ONE 9 , e87541 (doi:10.1371/journal.pone.0087541)), but show that the transition to Malthusian dynamics in this area is not abruptmore »but extends over centuries This article is part of the theme issue ‘Evolutionary ecology of inequality’.« less

Climate extremes are thought to have triggered large-scale transformations of various ancient societies, but they rarely seem to be the sole cause. It has been hypothesized that slow internal developments often made societies less resilient over time, setting them up for collapse. Here, we provide quantitative evidence for this idea. We use annual-resolution time series of building activity to demonstrate that repeated dramatic transformations of Pueblo cultures in the pre-Hispanic US Southwest were preceded by signals of critical slowing down, a dynamic hallmark of fragility. Declining stability of the status quo is consistent with archaeological evidence for increasing violence and in some cases, increasing wealth inequality toward the end of these periods. Our work thus supports the view that the cumulative impact of gradual processes may make societies more vulnerable through time, elevating the likelihood that a perturbation will trigger a large-scale transformation that includes radically rejecting the status quo and seeking alternative pathways.

El Panel Intergubernamental del Cambio Climático (IPCC por sus siglas en inglés) fue fundado en 1988 con el objetivo de proporcionar tanto evaluaciones de las ciencias climáticas relevantes a las políticas gubernamentales, como opciones para adaptación y mitigación a los gobiernos a nivel internacional. Al presente, este cuerpo intergubernamental es reconocido como la fuente principal de compilaciones sobre las investigaciones desde las ciencias climáticas, de adaptación y de mitigación. Los científicos que voluntariamente escriben los reportes para el IPCC han completado cinco ciclos de evaluaciones, y se encuentran trabajando en el sexto ciclo que terminarán en 2022. En este artículo, los autores revisamos cómo la información de y sobre la arqueología y otras formas de patrimonio cultural han sido incorporadas en estos reportes hasta el momento. Aún cuando esta revisión demuestra que la arqueología no ha estado totalmente ausente del trabajo del IPCC, los autores sugerimos que la arqueología tiene mucho más que ofrecer, tanto al IPCC como a la respuesta climática global. A estos efectos, proponemos cinco maneras en que tanto los arqueólogos como el conocimiento del pasado y sobre él pueden ser incorporados más plenamente en las evaluaciones y reportes del IPCC.

A constrained stochastic weather generator (CSWG) for producing daily mean air temperature and precipitation based on annual mean air temperature and precipitation from tree-ring records is developed and tested in this paper. The principle for stochastically generating daily mean air temperature assumes that temperatures in any year can be approximated by a sinusoidal wave function plus a perturbation from the baseline. The CSWG for stochastically producing daily precipitation is based on three additional assumptions: (1) In each month, the total precipitation can be estimated from annual precipitation if there exists a relationship between the annual and monthly precipitations. If that relationship exists, then (2) for each month, the number of dry days and the maximum daily precipitation can be estimated from the total precipitation in that month. Finally, (3) in each month, there exists a probability distribution of daily precipitation amount for each wet day. These assumptions allow the development of a weather generator that constrains statistically relevant daily temperature and precipitation predictions based on a specified annual value, and thus this study presents a unique method that can be used to explore historic (e.g., archeological questions) or future (e.g., climate change) daily weather conditions based upon specified annual values.

All species have an environmental niche, and despite technological advances, humans are unlikely to be an exception. Here, we demonstrate that for millennia, human populations have resided in the same narrow part of the climatic envelope available on the globe, characterized by a major mode around ∼11 °C to 15 °C mean annual temperature (MAT). Supporting the fundamental nature of this temperature niche, current production of crops and livestock is largely limited to the same conditions, and the same optimum has been found for agricultural and nonagricultural economic output of countries through analyses of year-to-year variation. We show that in a business-as-usual climate change scenario, the geographical position of this temperature niche is projected to shift more over the coming 50 y than it has moved since 6000 BP. Populations will not simply track the shifting climate, as adaptation in situ may address some of the challenges, and many other factors affect decisions to migrate. Nevertheless, in the absence of migration, one third of the global population is projected to experience a MAT >29 °C currently found in only 0.8% of the Earth’s land surface, mostly concentrated in the Sahara. As the potentially most affected regions are among the poorestmore »in the world, where adaptive capacity is low, enhancing human development in those areas should be a priority alongside climate mitigation.« less

Throughout the Holocene, societies developed additional layers of administration and more information-rich instruments for managing and recording transactions and events as they grew in population and territory. Yet, while such increases seem inevitable, they are not. Here we use the Seshat database to investigate the development of hundreds of polities, from multiple continents, over thousands of years. We find that sociopolitical development is dominated first by growth in polity scale, then by improvements in information processing and economic systems, and then by further increases in scale. We thus define a Scale Threshold for societies, beyond which growth in information processing becomes paramount, and an Information Threshold, which once crossed facilitates additional growth in scale. Polities diverge in socio-political features below the Information Threshold, but reconverge beyond it. We suggest an explanation for the evolutionary divergence between Old and New World polities based on phased growth in scale and information processing. We also suggest a mechanism to help explain social collapses with no evident external causes.

Este artículo investiga las dinámicas de la formación comunitaria a través de un análisis de los cambios diacrónicos en los patrones espaciales de las viviendas contemporáneas. Desarrollamos y aplicamos una rutina geoespacial para medir las extensiones y los patrones de interacción entre las viviendas desde dC 600 hasta 1280 en la cuesta Mesa Verde en el sudoeste de Colorado. Los resultados implican que la organización espacial entre las viviendas fue determinada simultáneamente por el mantenimiento de la interacción social habitual que sostenía las comunidades y por la separación espacial suficiente para la subsistencia de los grupos domésticos. Entre dC 600 y 1200, los grupos domésticos mantuvieron el equilibrio entre estos dos factores a través la formación de comunidades adicionales con asentamientos dispersos para mitigar varias presiones demográficas y ecológicas. Sin embargo, con el resurgimiento de la población después de la megasequía a mediados del siglo XII, las comunidades se volvieron cada vez más concentradas, alterando en cada comunidad el equilibrio existente entre la interacción de los grupos domésticos y sus espacios de subsistencia respectivos. Este cambio de la organización espacial de las comunidades generó vulnerabilidades que iban agravándose por los factores de un clima más frío, la sequía, la violencia,more »y otros cambios en la organización política y ritual a mediados del siglo XIII. La interacción entre estas presiones sociales y ambientales desembocó en la despoblación total de la cuesta Mesa Verde antes del fin del siglo XIII.« less