Abstract
The second-to-fourth finger length ratio (2D:4D) is an indication of prenatal sex hormone exposure, and has sex-specifically been associated with several lethal illnesses including ischemic heart disease, diverse cancers, and suicide. Our primary aim was to verify that 2D:4D sex-specifically relates to life expectancy and suicide numbers on a national level (23 countries). We also used a hypothesis-free approach to investigate associations with other causes of death [p value adjustment for multiple hypothesis testing using the false discovery rate procedure (FDR)]. All parameters were normalized to the national mean (of males and females) and analyzed across nations. Normalized male 2D:4D correlated positively with normalized male life expectancy (at birth, r = 0.46, p = 0.029; at the age of 60, r = 0.44, p = 0.038) and negatively with normalized male suicide rates (r = − 0.49, p = 0.017). In the exploratory analyses, the normalized male 2D:4D values were negatively associated with the normalized male deaths rates from communicable, maternal, perinatal, and nutritional conditions [r = − 0.65, p(FDR) = 0.011], respiratory infections [r = − 0.69, p(FDR) = 0.008], asthma [r = − 0.65, p(FDR) = 0.011], neurological conditions [r = − 0.56, p(FDR) = 0.046], and Alzheimer’s disease and other dementias [r = − 0.59, p(FDR) = 0.036]. The normalized female parameters showed the same cross-national correlations. In line with the previous individual level findings, the results suggest that prenatal sex hormone effects are sex-specifically involved in suicide and neurological conditions. Moreover, we provide novel national level evidence that prenatal sex hormone priming may sex-specifically influence life expectancy and death risk from respiratory diseases.
Highlights
Emerging evidence suggests that sex hormone levels during early developmental periods influence the risk of severe diseases with high mortality in later life
In support of our confirmatory hypotheses, normalized male 2D:4D correlated positively with normalized male life expectancy and negatively with normalized age-standardized male suicide rates across nations. These findings indicate that lower 2D:4D values might sex- be associated with reduced life expectancy and a higher risk for death by suicide
After correction for multiple hypothesis testing according to the false discovery rate procedure (FDR) procedure, the analyses revealed exclusively negative Pearson correlations
Summary
Emerging evidence suggests that sex hormone levels during early developmental periods influence the risk of severe diseases with high mortality in later life. 2011), gastric cancer (Nicolás Hopp et al 2013), disordered eating in males (Smith et al 2010), Alzheimer’s disease in males (Vladeanu et al 2014), coronary heart disease (Lu et al 2015), and myocardial infarction (Kyriakidis et al 2010). These studies, though, are often limited in sample size. Most findings have not been replicated and negative or contradictory results have been reported [e.g., prostate cancer (Muller et al 2011; García-Cruz et al 2012)]. The overall effect sizes may be over interpreted due to publication bias of positive findings
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