More men, more violence? Not so, review indicates
It is generally assumed that a surplus of men, a male-biased sex ratio, leads to more turbulent social interactions. Intuition suggests that all those males with all their testosterone competing for access to rare, valuable females can only result in aggression and violence.
However, the results of a review published in Trends in Ecology and Evolution, exploring correlations between biased sex ratios and violence were far less clear cut.
Where does the assumption that “more men = more violence” originate? The authors identified various sources:
- Mathematical – most people involved in violent interactions, whether the perpetrator or the victim, are male. Therefore, logic tells us that more men = more violence.
- Social science – in the 1980s researchers linking escalating violence rates in India to a heavily male-skewed sex ratio, suggesting this was a result of higher numbers of unmarried men (who are the group most likely to be engaged in violence)
- Sexual selection theory – in evolutionary biology, we are told in the traditional parental investment model that the sex involved most heavily in parental care and is therefore not always available for mating is a “limited resource”. The opposite sex must then compete for the few who are not at that time engaged in parental care, and it is generally assumed that competition results in violence.
Holes can be picked in all these sources, particularly in the applicability of sexual selection theory to humans. The authors of this review considered studies from across the world that looked at sex ratio and violence. They found equal numbers of studies where there was higher and lower violence in a male biased sex ratio society.
It is too simplistic to assume a straightforward positive or negative correlation between violence and sex ratio. For example, violence is not necessarily linked to competition for mates – mental illness, alcohol or other drugs, political unrest and anger management problems are all separate issues that can result in violence. Similarly, mate competition does not always result in violence. Female choice is an important factor that can influence this – if females choose based on male provisioning rather than physical strength, males would do best to invest in provisioning rather than aggression. The inability of the study to identify one pattern across these studies also reflects the fact that there are many differences between human cultures.
Here, the authors have proffered some interesting evidence against the assumptions that more men = more violence.
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