Digit ratio (2D:4D) and gender inequalities across nations
John T Manning1, Bernhard Fink2, Robert Trivers3
1Department of Psychology, Northumbria University, Newcastle-upon-Tyne, UK.
Summary
Prenatal hormone exposure, indicated by finger length ratios (2D:4D), correlates with national gender equality. Nations with similar 2D:4D ratios between sexes show greater female representation in parliament and the workforce.
Area of Science:
- Evolutionary biology
- Sociology
- Endocrinology
Background:
- Gender inequality is a global issue with varying degrees of female representation in social, economic, and political spheres.
- Economic prosperity is linked to gender equality, but the direction of causality is debated.
- The ratio of index (2D) to ring (4D) finger lengths (2D:4D) serves as a proxy for prenatal exposure to testosterone versus estrogen.
Purpose of the Study:
- To investigate the correlation between national gender inequality measures and average 2D:4D finger length ratios within populations.
- To explore the relationship between prenatal hormone exposure proxies and female representation in national governance and labor forces.
Main Methods:
- Compared male and female 2D:4D ratios across 29 countries.
- Correlated 2D:4D ratios with national data on female parliamentary representation, labor force participation, education levels, maternal mortality, and juvenile pregnancy rates.
Main Results:
- Nations with higher-than-expected female prenatal testosterone exposure (lower 2D:4D) and lower-than-expected male exposure (higher 2D:4D) exhibited greater female parliamentary representation and labor force participation.
- A convergence in 2D:4D ratios between sexes correlated with increased gender equality in political and economic spheres.
- Other measured variables showed weaker correlations with 2D:4D ratios.
Conclusions:
- Prenatal hormone exposure patterns, as indicated by 2D:4D ratios, may influence national levels of gender equality.
- Similarities in 2D:4D ratios between males and females could be a biological predictor of greater gender parity in societal roles.
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