Inconsistent with the data: Support for the CLASH model depends on the wrong kind of latitude (original) (raw)

The CLASH model lacks evolutionary and archeological support

Worldwide there are substantial differences within and between countries in aggression and violence. Although there are various exceptions, a general rule is that aggression and violence increase as one moves closer to the equator, which suggests the important role of climate differences. While this pattern is robust, theoretical explanations for these large differences in aggression and violence within countries and around the world are lacking. Most extant explanations focus on the influence of average temperature as a factor that triggers aggression (The General Aggression Model), or the notion that warm temperature allows for more social interaction situations (Routine Activity Theory) in which aggression is likely to unfold. We propose a new model, CLimate, Aggression, and Self-control in Humans (CLASH), that helps us to understand differences within and between countries in aggression and violence in terms of differences in climate. Lower temperatures, and especially larger degrees of seasonal variation in climate, call for individuals and groups to adopt a slower life history strategy, a greater focus on the future (vs. present), and a stronger focus on self-control. The CLASH model further outlines that slow life strategy, future orientation, and strong self-control are important determinants of inhibiting aggression and violence. We also discuss how CLASH differs from other recently developed models that emphasize climate differences for understanding conflict. We conclude by discussing the theoretical and societal importance of climate in shaping individual and societal differences in aggression and violence.

Hsiang, Influence of climate on Human conflict (2013)

A rapidly growing body of research examines whether human conflict can be affected by climatic changes. Drawing from archeology, criminology, economics, geography, history, political science, and psychology, we assemble and analyze the 60 most rigorous quantitative studies and document, for the first time, a remarkable convergence of results. We find strong causal evidence linking climatic events to human conflict across a range of spatial and temporal scales and across all major regions of the world. The magnitude of climate's influence is substantial: for each 1 standard deviation (1σ) change in climate toward warmer temperatures or more extreme rainfall, median estimates indicate that the frequency of interpersonal violence rises 4% and the frequency of intergroup conflict rises 14%. Because locations throughout the inhabited world are expected to warm 2-4σ by 2050, amplified rates of human conflict could represent a large and critical impact of anthropogenic climate change.

CLASH: Climate (change) and cultural evolution of intergroup conflict

Group Processes & Intergroup Relations

Aggression and violence levels generally increase as one moves closer to the equator, but why? We developed a new theoretical model, CLimate, Aggression, and Self-control in Humans (CLASH; van Lange, Rinderu, & Bushman, 2017b, 2017c), to understand differences within and between countries in aggression and violence in terms of differences in climate. Colder temperatures, and especially larger degrees of seasonal variation in climate, call for individuals and groups to adopt a slower life history strategy, revealed in a greater focus on the future (vs. present) and a stronger focus on self-control—variables that are known to inhibit aggression and violence. Other variables (e.g., wealth, income inequality, parasite stress) are also linked to both climate differences and to aggression and violence differences. When people think of the consequences of climate change, they rarely think of the impact on aggression and violence levels, but they should. CLASH has broad implications for the...

Climate, aggression, and violence (CLASH): a cultural-evolutionary approach

Current Opinion in Psychology

The CLimate, Aggression, and Self-control in Humans (CLASH) proposes that aggression and violence increase as climates become hotter and seasonal variation becomes smaller by influencing time-orientation and self-control. Emerging empirical evidence supporting the model is reviewed. Wealth, income inequality, and pathogen stress as powerful influences of these processes are also discussed. We conclude by discussing the theoretical and societal importance of climate change in shaping violence.

Climate, conflict, and social stability: what does the evidence say?

Climatic Change, 2013

Are violent conflict and socio-political stability associated with changes in climatological variables? We examine 50 rigorous quantitative studies on this question and find consistent support for a causal association between climatological changes and various conflict outcomes, at spatial scales ranging from individual buildings to the entire globe and at temporal scales ranging from an anomalous hour to an anomalous millennium. Multiple mechanisms that could explain this association have been proposed and are sometimes supported by findings, but the literature is currently unable to decisively exclude any proposed pathway. Several mechanisms likely contribute to the outcomes that we observe.

One effect to rule them all? A comment on climate and conflict

A recent Climatic Change review article reports a remarkable convergence of scientific evidence for a link between climatic events and violent intergroup conflict, thus departing markedly from other contemporary assessments of the empirical literature. This commentary revisits the review in order to understand the discrepancy. We believe the origins of the disagreement can be traced back to the review article's underlying quantitative meta-analysis,

Climate change and violent conflict in Europe over the last millennium

Climatic Change, 2010

We investigate the relationship between a thousand-year history of violent conflict in Europe and various reconstructions of temperature and precipitation. We find that conflict was more intense during colder periods. This relationship is weakening over time, and is not robust to the details of the climate reconstruction or to the sample period. We thus confirm Zhang et al. (2006, Climatic Change, 76, 459-477) that, at least in temperate climates, global warming would, if anything, lead to reduced violent conflict.

The Long-Term Patterns of Violent Conflict in Different Regions of the World

This paper is an interim report of a long-term project to develop a taxonomy of violent conflicts and ultimately a conflict early warning system. The paper first describes the nature of the conflict early warning problem---as the author perceives it---that shapes the design decisions the author has made. The paper then describes the Conflict Catalog, a listing of all recorded violent conflicts that meet Richardson's magnitude 1.5 or higher criterion (32 or more deaths). The Conflict Catalog is a dataset designed for the purpose of making a conflict taxonomy that is comprehensive in terms of the types of conflicts included and extensive in terms of encompassing conflicts in all regions of the world since 1400 AD. The paper presents "in-progress" findings from the catalog for the regions of the world for which a reasonably complete compilation has been assembled. The paper then describes a list of variables that define the criteria for placing historical conflicts into t...