The 2nd : 4th digit ratio, sexual dimorphism, population differences, and reproductive success: evidence for sexually antagonistic genes?

The ratio between the length of the 2nd and 4th digit (2D: 4D) is sexually dimorphic, with mean male 2D:4D lower than mean female 2D:4D. It recently w as suggested that 2D:4D is negatively correlated with prenatal testostcrone and positively correlated with prenatal estrogen. It is argued that high p renatal testosterone and low estrogen (indicated by low 2D:4D) favors the m ale fetus and low prenatal testosterone and high estrogen (indicated by hig h 2D:4D) favors the female fetus, The patterns of expression of 2D:4D are i nterpreted in terms of sexually antagonistic genes. We report data on the following, (a) reproductive success and 2D:4D from En gland, Germany, Spain, Hungary (ethnic Hungarians and Gypsy subjects), Pola nd, and Jamaica (women only). Significant negative associations were found between 2D:4D in men and reproductive success in the English and Spanish sa mples and significant positive relationships between 2D:4D in women and rep roductive success in the English, German, and Hungarian samples, The Englis h sample also showed that married women had higher 2D:4D ratios than unmarr ied women, suggesting male choice for a correlate of high ratio in women, a nd that a female 2D:4D ratio greater than male 2D:4D predicted high reprodu ctive success within couples. Comparison of 3D:3D ratios of 62 father:child pairs gave a significant positive relationship. This suggested that genes inherited fi om the father had some influence on the formation of the 2D:4D ratio. Waist:hip ratio in a sample of English and Jamaican women was negat ively related to 2D:3D. (b) Sex and population differences in mean 3D:3D in samples from England, Germany, Spain, Hungary (including ethnic Hungarians and Gypsy subjects), Poland, Jamaica, Finland, and South Africa (a Zulu sa mple). Significant sex and population differences in mean 2D:4D were appare nt. (C) 2000 Elsevier Science Inc. All rights reserved.