Introduction What is "gender based violence" (GBV)? GBV harms women and children Prevalence of GBV worldwide Attitudes to acceptability of GBV Trends in GBV prevalence and attitudes Patriarchal culture & "gender deviance neutralization" cause GBV Effects of female seclusion and nomadic pastoralism on GBV risk GBV is associated with childhood socialization GBV is bullying: a stronger person hits a weaker person GBV and women's earnings Alcohol increases the risk of GBV GBV may be related to cortisol GBV is sometimes a response to stressful temperatures We need a global intervention to reduce GBV Conclusion