Kusano, K. (草野広大) and Kemmelmeier, M. (2018). 
Ecology of freedom: Competitive tests of the role of pathogens, climate, and natural disasters in the development of socio-political freedom. 
Front. Psychol. 9:954. 
doi: 10.3389/fpsyg.2018.00954 

Many countries around the world embrace freedom and democracy as part of their political culture. However, culture is at least in part a human response to the ecological challenges that a society faces; hence, it should not be surprising that the degree to which societies regulate the level of individual freedom is related to environmental circumstances. Previous research suggests that levels of societal freedom across countries are systematically related to three types of ecological threats: prevalence of pathogens, climate challenges, and natural disaster threat. Though their incidence overlaps, the literature has not yet provided a competitive test. Drawing upon the ecocultural framework, we tested five rival hypotheses, alternately focused on the above ecological factors and their interactions with economic wealth in explaining country variations in socio-political freedom. Focusing on data from 150 countries, we performed a series of linear mixed-effects regressions predicting freedom in the domains of politics, media, and economy. We found that countries with higher pathogen prevalence were more likely to suppress democracy and media freedom. Economic wealth, however, moderated the effect of pathogen prevalence on economic freedom, with the main effect being only found among wealthy countries, but not among poor countries. In contrast, natural disaster threat predicted political freedom and press freedom only among poor countries, consistent with the idea that disaster threat accompanied by poor resources promote socio-political freedom as a means of increasing collective survival. Throughout our analyses, we found no support for hypotheses based on climatic challenges. In addition, our multilevel approach revealed that country scores for socio-political freedom were highly clustered within world regions, accounting for substantial portions of variance. Overall, the present research offers a nuanced view of the interplay between ecology and wealth in the emergence of socio-political freedom. We discuss new directions in future research considering methodological and theoretical contributions of the present findings. 

文化心理学では、環境が社会や心理にどのように影響を与えるのかと言う点について、様々な研究がなされてきた。先行研究は、主に病原体、気候、自然災害の3つの環境要因と、個人主義や民主主義などの国レベルの自由の指標の関係を検証する研究が多く行われて来た。病原体、気候、自然災害などの要因は、互いに独立していない環境要因であるにも関わらず、先行研究では、これらの要因についての理論を包括的に検証する試みがなされていなかった。そこで本研究では、これら3つの環境要因と、経済的豊かさ(GDP per capita)を全て考慮したモデルを検証した。さらに本研究は、先行研究の国レベルの分析における統計的な誤り(独立性の仮定)を指摘し、マルチレベル分析を用いることで、独立性の無視によって起こる推定バイアスを部分的に調整した。その結果、病原菌感染率の低い国においては、民主主義が高まる傾向にある、といった示唆が得られた。