2D:4D Asymmetry and Gender Differences in Academic Performance

Abstract

Exposure to prenatal androgens affects both future behavior and life choices. However, there is still relatively limited evidence on its effects on academic performance. Moreover, the predicted effect of exposure to prenatal testosterone (T)–which is inversely correlated with the relative length of the second to fourth finger lengths (2D:4D)–would seem to have ambiguous effects on academic achievement since traits like aggressiveness or risk-taking are not uniformly positive for success in school. We provide the first evidence of a non-linear, quadratic, relationship between 2D:4D and academic achievement using samples from Moscow and Manila. We also find that there is a gender differentiated link between various measures of academic achievement and measured digit ratios. These effects are different depending on the field of study, choice of achievement measure, and use of the right hand or left digit ratios. The results seem to be asymmetric between Moscow and Manila where the right (left) hand generates inverted-U (U-shaped) curves in Moscow while the pattern for hands reverses in Manila. Drawing from unusually large and detailed samples of university students in two countries not studied in the digit literature, our work is the first to have a large cross country comparison that includes two groups with very different ethnic compositions.

Second-to-Fourth Digit Ratio Has a Non-Monotonic Impact on Altruism

“…Non-monotonicity may be particularly important in case of biological traits, since they are shaped by evolutionary forces toward “optimal” values [10]–[12] and deviations from these values in any direction might matter. Such an argument is supported by Nye et al [13] who find systematic non-monotonic associations between digit ratio and several measures of academic performance.…”

“…On the other hand, some studies have already suggested non-monotonic impacts of 2D:4D on some behavioral outcomes (e.g. [13], [40], [51], [52]). …”

The influence of prenatal hormones on occupational choice: 2D:4D evidence from Moscow

“…Previous results based on university students provided the first evidence of a non-linear relationship between 2D:4D and academic achievement using samples from Moscow and Manila. They found that there is a quadratic relationship between high T exposure and markers of achievement such as grades or test scores and that the optimum digit ratio for women in our sample is lower (indicating higher prenatal T) than the average with little to no significant correlations for men (Nye, Androuschak, Desierto, Jones, & Yudkevich, 2012). There may be nonlinearities regarding which women are likely to enter or leave occupations when ranked by skill complexity, status, or income.…”

2D:4D and Lifetime Educational Outcomes: Evidence from the Russian RLMS Survey

“…We noted earlier that in some studies nonlinear associations of 2D:4D and educational outcomes were found (John V C Nye et al 2012;Sánchez et al 2014). To check for other possible non-monotonic associations and predictors we squared the 2D:4D and included them in regressions with multiple controls (see Table A 14- Table A 16).…”

“…As argued by Nye et al (John V C Nye et al 2012) and Nye et al (J V C Nye and Orel 2015), because we have good reason to believe that traits such as confidence or risk-taking or other non-cognitive characteristics are likely to have more positive effects in moderation than at the extremes, we should observe that 2D:4D should exhibit some non-linearity in outcomes, which would have weakened their influence and led to inconsistent findings in literature which only considered first order correlations or linear regressions. Some evidence of nonlinear specifications for these relationships came from the studies of Nye et al for 2D:4D and grades/test scores (John V C Nye et al 2012) and for wages (Nye et al 2014) and Neckerman 1989), limiting the ability to successfully continue education after secondary school. Therefore, one can expect positive correlations between male higher 2D:4D and the completed level of education.…”