Comparing and Contrasting Rates of Firearm Homicides and Suicides

The present research investigates relations among social-biogeographic factors (i.e., temperature, parasite burden, poverty rate, firearm possession rate, psychopathology rate, and estimated IQ), firearm homicide rate, and firearm suicide rate in each of the 50 states of the United States of America. Analysis of archival state-level data showed that local parasite burden strongly and positively predicted firearm homicide rate ( sR = .58, p = < .0001). In contrast, both firearms possession rate ( sR = −.18, p = .008) and State psychopathology rate ( sR = −.34, p = < .0001) negatively predicted firearm homicide rate. In contrast, State psychopathology rate alone positively predicted suicide rate ( sR = .42, p = < .0001). These results, which we discuss in terms of Thornhill’s and Fincher’s Parasite-Stress Model ( 2011 ), can be used to provide behavior-driven alternative models of behavior to guide political policy making and therapeutic interventions.