Digit ratio (2D:4D) and social integration: An effect of prenatal sex hormones

Abstract

The position people occupy in their social and professional networks is related to their social status and has strong e↵ects on their access to social resources. While attainment of particular positions is driven by behavioral traits, many biological factors predispose individuals to certain behaviors and motivations. Prior work on exposure to fetal androgens (measured by second-to-fourth digit ratio, 2D:4D) shows that it correlates with behaviors and traits related to social status, which might make people more socially integrated. However, it also predicts certain anti-social behaviors and disorders associated with lower socialization. We explore whether 2D:4D correlates with network position later in life and find that individuals with low 2D:4D become more central in their social environment. Interestingly, low 2D:4D males are more likely to exhibit high betweenness centrality (they connect separated parts of the social structure) while low 2D:4D females are more likely to exhibit high in-degree centrality (more people name them as friends). These gender-specific di↵erences are reinforced by transitivity (the likelihood that one's friends are also friends with one another): neighbors of low 2D:4D men tend not to know each other; the contrary is observed for low 2D:4D women. Our results suggest that biological predispositions influence the organization of human societies and that exposure to prenatal androgens influences di↵erent status seeking behaviors in men and women.

The Effect of Testosterone Administration and Digit Ratio (2D:4D) on Implicit Preference for Status Goods in Healthy Males

“…For instance, 2D:4D ratio is significantly associated with risk preferences over lotteries with real monetary incentives (Brañas-Garza et al, in press ). Recent research also showed that 2D:4D ratio correlates with social network centrality (Kovářík et al, 2017 ). In the current study, this association was abolished by testosterone treatment, possibly due to the enhancing effect of testosterone for status-goods among individuals with higher 2D:4D ratio (less masculine).…”

Digit ratio (2D : 4D) and prosocial behaviour in economic games: no direct correlation with generosity, bargaining or trust-related behaviours

“…Consequently, males tend to display lower 2D : 4D values than females [35,36]. Many studies, some using large samples, have analysed the association between 2D : 4D and diverse aspects of social involvement and interactions, including status seeking [37], social network positioning [38] and managerial ability [39].…”

Lower Digit Ratio (2D:4D) Indicative of Excess Prenatal Androgen Is Associated With Increased Sociability and Greater Social Capital

“…Thus, in contrast to what one might expect due to the above reported sex differences, men with lower (more masculine) 2D:4D perform better in tasks that require networking or bonding. Accordingly, in men, lower 2D:4D has been related to more fairness (Millet and Dewitte, 2006), stronger cognitive reflection (Bosch-Domenèch et al, 2014), and higher betweenness centrality, i.e., they connect separated parts of the social structure (Kovářík et al, 2017). Moreover, males with lower 2D:4D show more courtship behavior in social interactions with women (Roney and Maestripieri, 2004).…”