Fighting ability, largely determined by upper body strength, continues to rule the minds of modern men, according to a new study¹ by Aaron Sell from Griffith University in Australia and colleagues.

Their work explores the concept that human males are designed for fighting, and shows how this fighting ability drives both their behavior and attitudes to a range issues, including political orientation. For example, their research demonstrates that among Hollywood actors, those selected for their physical strength, i.e. action stars, are more likely to support the Republican position on foreign policy. The study is published online in Springer's journal Human Nature, and is part of a special issue² on the evolution of human aggression.

Multiple research disciplines have found evidence that our male ancestors used physical aggression to compete for status. The evidence shows how this competition led to the evolution of numerous physical and psychological sex differences. Sell and team's review highlights the sheer number of physical and mental features that show evidence of special design for physical aggression in men, compared to women. These features include abilities to dissipate heat, perceive and respond rapidly to threats, estimate the trajectory of thrown objects, resist blunt-force trauma and accurately intercept objects.

While fighting ability was undoubtedly essential when man was a hunter-gatherer, how important and influential is it today? According to Sell and colleagues' work, man's fighting ability is still a major influence on his attitudes and behavioral responses.

Multiple studies conducted from the US, East India, Bolivia and the Central African Republic show that physically strong men have a greater sense of entitlement, a shorter fuse on anger, and are more likely to turn aggressive when angry. The effects are quite substantial, often two to four times larger than the known effect of testosterone on aggression.

The authors applied the same analysis to attitudes on warfare and found that stronger men, compared to weaker men, were more likely to believe in the utility of political aggression as a means of resolving conflicts of interest. Using a sample of Hollywood stars they demonstrated that those actors known for their physical strength and formidability, among them Arnold Schwarzenegger, Bruce Willis, Chuck Norris and Sylvester Stallone, were more likely to support military action. Generally speaking, Hollywood actors are left wing, but the action stars among them were more likely than not to support the Republican position on foreign policy.

The authors conclude: "Upper body strength in adult males is a crucial variable that appears to have impacts on a wide range of mental mechanisms. These mechanisms were designed by natural selection at a time when personal physical aggression was far more common and individual differences in fighting ability were far more relevant for the resolution of conflicts. Despite the steady decline in physical aggression and violent deaths that have accompanied Western civilization, the human mind is still designed for ancestral environments."