Disentangling the evolutionary drivers of social complexity: A comprehensive test of hypotheses.

During the Holocene, the scale and complexity of human societies increased markedly. Generations of scholars have proposed different theories explaining this expansion, which range from broadly functionalist explanations, focusing on the provision of public goods, to conflict theories, emphasizing the role of class struggle or warfare. To quantitatively test these theories, we develop a general dynamical model based on the theoretical framework of cultural macroevolution. Using this model and Seshat: Global History Databank, we test 17 potential predictor variables proxying mechanisms suggested by major theories of sociopolitical complexity (and >100,000 combinations of these predictors). The best-supported model indicates a strong causal role played by a combination of increasing agricultural productivity and invention/adoption of military technologies (most notably, iron weapons and cavalry in the first millennium BCE).

A randomized trial of cash incentives for sexual behavior change among female sex workers in Dar es Salaam.

RATIONALE: Female sex workers (FSW) across the world are at high risk for HIV infection and much work is needed to scale up HIV prevention programs among this group. Conditional cash transfer (CCT) programs have been used successfully in recent years to encourage behavior change. We report the results of a CCT intervention among FSW in Tanzania. METHODS: We conducted a randomized controlled trial (N = 100) of a CCT intervention among FSW in Dar-es-Salaam, Tanzania in 2013. A respondent-driven sampling approach recruited women and randomized them into two groups based on the value of the cash incentive ($20 vs. $40 per visit). All women received testing for 2 curable sexually transmitted infections (STIs), trichomonas and syphilis, free treatment for those STIs and counseling. Women attended study visits at 0, 2 and 4 months and were tested for STIs and received counseling at each visit. Women testing negative for both STIs at the 2- and 4-month visits received a cash reward. RESULTS: Eighty-four women were retained in the study through all three visits. Participants reported significant reductions in the number of clients per week, and increases in the proportion of clients that they used condoms with over the course of the study. STI results showed decreases in prevalence from baseline to final study visit for syphilis and trichomonas. CONCLUSION: While this study was not powered to determine if the incentive resulted in statistically significant increases in condom use or decreases in STI prevalence, the results show the acceptability of the intervention, the feasibility of the recruitment methods, and the ability to retain FSW participants across multiple study visits. A follow-up randomized study with a larger number of participants is planned to test the efficacy of the intervention among high-risk populations of women engaging in transactional sex.

Complex societies precede moralizing gods throughout world history.

The origins of religion and of complex societies represent evolutionary puzzles1-8. The 'moralizing gods' hypothesis offers a solution to both puzzles by proposing that belief in morally concerned supernatural agents culturally evolved to facilitate cooperation among strangers in large-scale societies9-13. Although previous research has suggested an association between the presence of moralizing gods and social complexity3,6,7,9-18, the relationship between the two is disputed9-13,19-24, and attempts to establish causality have been hampered by limitations in the availability of detailed global longitudinal data. To overcome these limitations, here we systematically coded records from 414 societies that span the past 10,000 years from 30 regions around the world, using 51 measures of social complexity and 4 measures of supernatural enforcement of morality. Our analyses not only confirm the association between moralizing gods and social complexity, but also reveal that moralizing gods follow-rather than precede-large increases in social complexity. Contrary to previous predictions9,12,16,18, powerful moralizing 'big gods' and prosocial supernatural punishment tend to appear only after the emergence of 'megasocieties' with populations of more than around one million people. Moralizing gods are not a prerequisite for the evolution of social complexity, but they may help to sustain and expand complex multi-ethnic empires after they have become established. By contrast, rituals that facilitate the standardization of religious traditions across large populations25,26 generally precede the appearance of moralizing gods. This suggests that ritual practices were more important than the particular content of religious belief to the initial rise of social complexity.

Building community resilience: what can the United States learn from experiences in other countries?

OBJECTIVES: Community resilience (CR) is emerging as a major public policy priority within disaster management and is one of two key pillars of the December 2009 US National Health Security Strategy. However, there is no clear agreement on what key elements constitute CR. We examined exemplary practices from international disaster management to validate the elements of CR, as suggested by Homeland Security Presidential Directive 21 (HSPD-21), to potentially identify new elements and to identify practices that could be emulated or adapted to help build CR. METHODS: We extracted detailed information relevant to CR from unpublished case studies we had developed previously, describing exemplary practices from international natural disasters occurring between 1985 and 2005. We then mapped specific practices against the five elements of CR suggested by HSPD-21. RESULTS: We identified 49 relevant exemplary practices from 11 natural disasters in 10 countries (earthquakes in Mexico, India, and Iran; volcanic eruption in Philippines; hurricanes in Honduras and Cuba; floods in Bangladesh, Vietnam, and Mozambique; tsunami in Indian Ocean countries; and typhoon in Vietnam). Of these, 35 mapped well against the five elements of CR: community education, community empowerment, practice, social networks, and familiarity with local services; 15 additional practices were related to physical security and economic security. The five HSPD-21 CR elements and two additional ones we identified were closely related to one another; social networks were especially important to CR. CONCLUSIONS: While each disaster is unique, the elements of CR appear to be broadly applicable across countries and disaster settings. Our descriptive study provides retrospective empirical evidence that helps validate, and adds to, the elements of CR suggested by HSPD-21. It also generates hypotheses about factors contributing to CR that can be tested in future analytic or experimental research.