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

  Objectives 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.