The negative social outcomes in populations with male-biased sex ratios are a growing concern. In general, the expectation is of heightened violence as a result of excess men engaging in antisocial behavior and crime, thereby threatening societal stability. While intuitive, these claims are largely unsupported in the literature. Using mating market theory as our guide, we examine indicators of male mating effort, including (1) violent competition between men (homicide, aggravated assault) and (2) indicators of uncommitted sexual behavior (rape, sex offenses, and prostitution). Our unit of analysis is U.S. county-level data. We find that counties with more men have lower rates of crime and violent behavior. Our findings challenge conventional claims of male excess leading to elevated levels of violence. Instead, in support of mating market predictions, we find that criminal and violent behavior related to male mating effort is least common in male-biased sex ratios. We discuss the implications of our findings for public policy regarding incarceration and criminal behavior.
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We are grateful to Elizabeth Cashdan, Karen L. Kramer, and Kristen Hawkes for their comments during the preparation of the manuscript. We also thank three anonymous reviewers and the guest editors, Rebecca Sear and Siobhán M. Mattison, for their detailed and insightful comments. Through of all their thoughtful work, both our manuscript and our thinking on the topic were much improved.
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Schacht, R., Tharp, D. & Smith, K.R. Marriage Markets and Male Mating Effort: Violence and Crime Are Elevated Where Men Are Rare. Hum Nat 27, 489–500 (2016). https://doi.org/10.1007/s12110-016-9271-x
- Sex ratio
- Parental investment
- Mating market
- Sexual selection