Digit ratio (2D:4D), mate guarding, and physical aggression in dating couples

The current study assessed digit ratio (2D:4D) and mate guarding in 101 dating couples. Low 2D:4D men (indicating higher prenatal testosterone exposure) were more likely to state that they threatened male competitors and used more threats and physical aggression toward their female partners. Men were particularly likely to use threats and physical aggression toward partners who cheated in the current relationship. In addition, women resisted mate guarding by men with high 2D:4D, particularly when women cheated on their partner. High 2D:4D women were more possessive toward their partner. This is consistent with ideas regarding the effects of sexual selection on mate guarding.