Digit ratio (2D:4D), aggression, and dominance in the Hadza and the Datoga of Tanzania.

Objective: Digit ratio (2D:4D)-a putative marker of prenatal androgen activity-has been shown to correlate with self-reported physical aggression and dominance behavior, especially in male children and adolescents. This evidence is derived primarily from the study of Western samples.

Methods: Digit ratios, self-reported aggression, and dominance behavior were collected from men and women in two traditional, small-scale societies, i.e., the Hadza and the Datoga of Tanzania.

Results: We found significant differences in physical and verbal aggression, anger, and hostility between the two societies with the Datoga reporting higher scores on all four measures. Moreover, self-reported dominance in the Datoga was higher than in the Hadza. The Datoga showed lower left and right hand 2D:4D ratios than the Hadza. Men reported higher physical and verbal aggression and dominance, and had lower 2D:4D ratios than women. A significant negative association between 2D:4D and dominance was found in Hadza women.

Conclusions: We discuss our findings with reference to differences in mating systems between the two small-scale societies and previous findings of Western and other small-scale societies.