skip to main content

Title: Loss of resilience preceded transformations of pre-Hispanic Pueblo societies
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.  more » « less
Award ID(s):
1637171 1620462
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
Proceedings of the National Academy of Sciences
Page Range / eLocation ID:
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Increasing population and rural to urban migration are accelerating urbanization globally, permanently transforming natural systems over large extents. Modelling landscape change over large regions, however, presents particular challenges due to local-scale variations in social and environmental factors that drive land change. We simulated urban development across the South Atlantic States (SAS), a region experiencing rapid population growth and urbanization, using FUTURES—an open source land change model that uses demand for development, local development suitability factors, and a stochastic patch growing algorithm for projecting alternative futures of urban form and landscape change. New advances to the FUTURES modelling framework allow for high resolution projections over large spatial extents by leveraging parallel computing. We simulated the adoption of different urban growth strategies that encourage settlement densification in the SAS as alternatives to the region’s increasing sprawl. Evaluation of projected patterns indicate a 15% increase in urban lands by 2050 given a status quo development scenario compared to a 14.8% increase for the Infill strategy. Status quo development resulted in a 3.72% loss of total forests, 2.97% loss of highly suitable agricultural land, and 3.69% loss of ecologically significant lands. An alternative Infill scenario resulted in similar losses of total forest (3.62%) and ecologically significant lands (3.63%) yet consumed less agricultural lands (1.23% loss). Moreover, infill development patterns differed qualitatively from the status quo and resulted in less fragmentation of the landscape. 
    more » « less
  2. null (Ed.)
    Abstract Sub-Saharan Africa (SSA) is undergoing rapid transformations in the realm of union formation in tandem with significant educational expansion and rising labor force participation rates. Concurrently, the region remains the least developed and most unequal along multiple dimensions of human and social development. In spite of this unique scenario, never has the social stratification literature examined patterns and implications of educational assortative mating for inequality in SSA. Using 126 Demographic and Health Surveys from 39 SSA countries between 1986 and 2016, this study is the first to document changing patterns of educational assortative mating by marriage cohort, subregion, and household location of residence and relate them to prevailing sociological theories on mating and development. Results show that net of shifts in educational distributions, mating has increased over marriage cohorts in all subregions except for Southern Africa, with increases driven mostly by rural areas. Trends in rural areas align with the status attainment hypothesis, whereas trends in urban areas are consistent with the inverted U-curve framework and the increasing applicability of the general openness hypothesis. The inequality analysis conducted through a combination of variance decomposition and counterfactual approaches reveals that mating accounts for a nonnegligible share (3% to 12%) of the cohort-specific inequality in household wealth, yet changes in mating over time hardly move time trends in wealth inequality, which is in line with findings from high-income societies. 
    more » « less
  3. Purpose The authors use a co-auto-ethnographic study of Hurricane Harvey where both authors were citizen responders and disaster researchers. In practice, large-scale disaster helps temporarily foster an ideal of community which is then appropriated by emergency management institutions. The advancement of disaster research must look to more radical perspectives on human response in disaster and what this means for the formation of communities and society itself. It is the collective task as those invested in the management of crises defer to the potentials of publics, rather than disdain and appropriate them. The authors present this work in the advancement of more empirically informed mitigation of societal ills that produce major causes of disaster. The authors’ work presents a departure from the more traditional disaster work into a critical and theoretical realm using novel research methods. The paper aims to discuss these issues. Design/methodology/approach This paper produces a co-auto-ethnographic study of Hurricane Harvey where both authors were citizen responders and disaster researchers. Findings The authors provide a critical, theoretical argument that citizen-based response fosters an ephemeral utopia not usually experienced in everyday life. Disasters present the possibility of an ideal of community. These phenomena, in part, allow us to live our better selves in the case of citizen response and provide a direct contrast to the modern experience. Modernity is a mostly fabricated, if not almost eradicated sense of community. Modern institutions, serve as sources of domination built on the backs of technology, continuity of infrastructures and self-sufficiency when disasters handicap society, unpredictability breaks illusions of modernity. There arises a need to re-engage with those around us in meaningful and exciting ways. Research limitations/implications This work produces theory rather than engage in testing theory. It is subject to all the limitations of interpretive work that focuses on meaning and critique rather than advancing associations or causality. Practical implications The authors suggest large-scale disasters will persist to overwhelm management institutions no matter how much preparedness and planning occurs. The authors also offer an alternative suggestion to the institutional status quo system based on the research; let the citizenry do what they already do, whereas institutions focus more on mitigate of social ills that lead to disaster. This is particularly urgent given increasing risk of events exacerbated by anthropogenic causes. Social implications The advancement of disaster research must look to more radical perspectives on human response in disaster and what this means for the formation of communities and society itself. It is the collective task as those invested in the management of crises to defer to the potentials of publics, rather than disdain and appropriate them. The authors also suggest that meaningful mitigation of social ills that recognize and emphasize difference will be the only way to manage future large-scale events. Originality/value The authors’ work presents a departure from the more practical utility of disaster work into a critical and highly theoretical realm using novel research methods. 
    more » « less
  4. Many applications that use large-scale machine learning (ML) increasingly prefer different models for subgroups (e.g., countries) to improve accuracy, fairness, or other desiderata. We call this emerging popular practice learning over groups , analogizing to GROUP BY in SQL, albeit for ML training instead of SQL aggregates. From the systems standpoint, this practice compounds the already data-intensive workload of ML model selection (e.g., hyperparameter tuning). Often, thousands of models may need to be trained, necessitating high-throughput parallel execution. Alas, most ML systems today focus on training one model at a time or at best, parallelizing hyperparameter tuning. This status quo leads to resource wastage, low throughput, and high runtimes. In this work, we take the first step towards enabling and optimizing learning over groups from the data systems standpoint for three popular classes of ML: linear models, neural networks, and gradient-boosted decision trees. Analytically and empirically, we compare standard approaches to execute this workload today: task-parallelism and data-parallelism. We find neither is universally dominant. We put forth a novel hybrid approach we call grouped learning that avoids redundancy in communications and I/O using a novel form of parallel gradient descent we call Gradient Accumulation Parallelism (GAP). We prototype our ideas into a system we call Kingpin built on top of existing ML tools and the flexible massively-parallel runtime Ray. An extensive empirical evaluation on large ML benchmark datasets shows that Kingpin matches or is 4x to 14x faster than state-of-the-art ML systems, including Ray's native execution and PyTorch DDP. 
    more » « less
  5. Abstract

    Although biological invasions play an important role in ecosystem change worldwide, little is known about how invasions are influenced by local abiotic stressors. Broadly, abiotic stressors can cause large-scale community changes in an ecosystem that influence its resilience. The possibility for these stressors to increase as global changes intensify highlights the pressing need to understand and characterize the effects that abiotic drivers may have on the dynamics and composition of a community. Here, we analyzed 26 years of weekly abundance data using the theory of regime shifts to understand how the structure of a resident community of dung beetles (composed of dweller and tunneler functional groups) responds to climatic changes in the presence of the invasive tunnelerDigitonthophagus gazella. Although the community showed an initial dominance by the invader that decreased over time, the theory of regime shifts reveals the possibility of an ecological transition driven by climate factors (summarized here in a climatic index that combines minimum temperature and relative humidity). Mid and low values of the driver led to the existence of two alternative stable states for the community structure (i.e. dominance of either dwellers or tunnelers for similar values of the climatic driver), whereas large values of the driver led to the single dominance by tunnelers. We also quantified the stability of these states against climatic changes (resilience), which provides insight on the conditions under which the success of an invasion and/or the recovery of the previous status quo for the ecosystem are expected. Our approach can help understand the role of climatic changes in community responses, and improve our capacity to deal with regime shifts caused by the introduction of exotic species in new ecosystems.

    more » « less