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.

This research evaluates the time competence of the aged in relation to sex, age, living environment, activities, health, and socio-economic status. One hundred and sixty subjects answered a socio-demographic questionnaire. Level of time competence was evaluated by the time competence subscale of the Personal Orientation Inventory (POI) (Shostrom, 1966) and by the estimate of an interval of 40 seconds (Newman, 1972, 1976). Analysis of variance shows that level of time competence varies according to age, satisfaction in the number of activities, subjective assessment of health and living environment. These results show the possible importance of objective health in the evaluation of the time competence. In fact, subjects from the 65–75 age group living in institutions show more physical deterioration than the other subjects and less time competence. For the older subjects, time competence does not differ according to the life environment. It would therefore be important, in further studies, to take this variable into account. These results and those of earlier studies reveal that the personnel have to take into account the rate of activities imposed on the beneficiaries by their health condition when developing programs of activities because time competence also varies according to satisfaction with the number of activities. The results also cast a doubt on the sensitivity of the estimate of this particular time competence measure requiring an interval of 40 seconds.