Stronger men are more likely than average to exhibit outward displays of anger. Researchers have measured men's handgrip strength, the amount of weight each participant could lift, bicep circumference, etc.—controlling for body‑fat percentage and other factors. The result was striking: stronger men were consistently more prone to anger. That pattern held not only in American samples but also among hunter‑gatherer groups in Peru and Central Africa. Anger seems to work as an effective bargaining tool for physically formidable men.