PNAS – Proceedings of the National Academy of Sciences of the United States of America
(Accessed 15 November 2014)
http://www.pnas.org/content/early/

Effects of temperature and precipitation variability on the risk of violence in sub-Saharan Africa, 1980–2012
John O’Loughlina,1, Andrew M. Linkea, and Frank D. W. Witmerb
Author Affiliations
Edited by B. L. Turner, Arizona State University, Tempe, AZ, and approved October 9, 2014
Significance
A robust debate about the effects of climate change on conflict occurrences has attained wide public and policy attention, with sub-Saharan Africa generally viewed as most susceptible to increased conflict risk. Using a new disaggregated dataset of violence and climate anomaly measures (temperature and precipitation variations from normal) for sub-Saharan Africa 1980–2012, we consider political, economic, and geographic factors, not only climate metrics, in assessing the chances of increased violence. The location and timing of violence are influenced less by climate anomalies than by key political, economic, and geographic factors. Overall, the temperature effect is statistically significant, but important inconsistencies in the relationship between temperature extremes and conflict are evident in more nuanced relationships than have been previously identified.
Abstract
Ongoing debates in the academic community and in the public policy arena continue without clear resolution about the significance of global climate change for the risk of increased conflict. Sub-Saharan Africa is generally agreed to be the region most vulnerable to such climate impacts. Using a large database of conflict events and detailed climatological data covering the period 1980–2012, we apply a multilevel modeling technique that allows for a more nuanced understanding of a climate–conflict link than has been seen heretofore. In the aggregate, high temperature extremes are associated with more conflict; however, different types of conflict and different subregions do not show consistent relationship with temperature deviations. Precipitation deviations, both high and low, are generally not significant. The location and timing of violence are influenced less by climate anomalies (temperature or precipitation variations from normal) than by key political, economic, and geographic factors. We find important distinctions in the relationship between temperature extremes and conflict by using multiple methods of analysis and by exploiting our time-series cross-sectional dataset for disaggregated analyses.

The ecology of religious beliefs
Carlos A. Boteroa,b,1, Beth Gardnerc, Kathryn R. Kirbyd, Joseph Bulbuliae, Michael C. Gavinf, and Russell D. Grayg,h,iAuthor Affiliations
Edited by Ara Norenzayan, University of British Columbia, Vancouver, Canada, and accepted by the Editorial Board October 10, 2014 (received for review May 11, 2014)
Significance
Here we show that the spatial prevalence of human societies that believe in moralizing high gods can be predicted with a high level of accuracy (91%) from historical, social, and ecological data. Using high-resolution datasets, we systematically estimate the relative effects of resource abundance, ecological risk, cultural diffusion, shared ancestry, and political complexity on the global distribution of beliefs in moralizing high gods. The methods presented in this paper provide a blueprint for how to leverage the increasing wealth of ecological, linguistic, and historical data to understand the forces that have shaped the behavior of our own species.
Abstract
Although ecological forces are known to shape the expression of sociality across a broad range of biological taxa, their role in shaping human behavior is currently disputed. Both comparative and experimental evidence indicate that beliefs in moralizing high gods promote cooperation among humans, a behavioral attribute known to correlate with environmental harshness in nonhuman animals. Here we combine fine-grained bioclimatic data with the latest statistical tools from ecology and the social sciences to evaluate the potential effects of environmental forces, language history, and culture on the global distribution of belief in moralizing high gods (n = 583 societies). After simultaneously accounting for potential nonindependence among societies because of shared ancestry and cultural diffusion, we find that these beliefs are more prevalent among societies that inhabit poorer environments and are more prone to ecological duress. In addition, we find that these beliefs are more likely in politically complex societies that recognize rights to movable property. Overall, our multimodel inference approach predicts the global distribution of beliefs in moralizing high gods with an accuracy of 91%, and estimates the relative importance of different potential mechanisms by which this spatial pattern may have arisen. The emerging picture is neither one of pure cultural transmission nor of simple ecological determinism, but rather a complex mixture of social, cultural, and environmental influences. Our methods and findings provide a blueprint for how the increasing wealth of ecological, linguistic, and historical data can be leveraged to understand the forces that have shaped the behavior of our own species.

Brothers in arms: Libyan revolutionaries bond like family
Harvey Whitehousea,1, Brian McQuinna, Michael Buhrmestera, and William B. Swann, Jr.b
Author Affiliations
Edited by Susan T. Fiske, Princeton University, Princeton, NJ, and approved October 9, 2014
Significance
The human propensity to sacrifice one’s life for genetic strangers has puzzled scientists since Darwin. Here, we sought answers to this puzzle by embedding ourselves within groups of individuals prepared to die for one another—Libyan revolutionary battalion members who fought against Gaddafi’s regime in 2011. We found striking evidence of extraordinarily tight, familial-like bonds among those who put themselves directly in harm’s way (i.e., frontline combatants). In fact, for nearly half of combatants, their bonds to each other were stronger than bonds to their own families. Moreover, these kin-like bonds to one another predispose them to extreme self-sacrifice.
Abstract
What motivates ordinary civilians to sacrifice their lives for revolutionary causes? We surveyed 179 Libyan revolutionaries during the 2011 conflict in Libya. These civilians-turned-fighters rejected Gaddafi’s jamahiriyya (state of the masses) and formed highly cohesive fighting units typical of intense conflicts. Fighters reported high levels of “identity fusion”—visceral, family-like bonds between fighters and their battalions. Fusion of revolutionaries with their local battalions and their own families were extremely high, especially relative to Libyans who favored the revolution but did not join battalions. Additionally, frontline combatants were as strongly bonded to their battalion as they were to their own families, but battalion members who provided logistical support were more fused with their families than battalions. Together, these findings help illuminate the social bonds that seem to motivate combatants to risk their lives for the group during wartime.