Second to fourth digit ratio and hand skill in Austrian children

Prenatal exposure to testosterone is thought to promote the development of the right-hemisphere and increase the incidence of sinistrality. A direct test of this hypothesis has previously been prob-lematic because of the difficulty of indirectly assessing prenatal sex steroid exposure. Evidence now suggests that the ratio between the length of the second and fourth digits (2D:4D) is related to prenatal testosterone exposure. We tested whether digit ratio is related to the degree of hand skill such that low 2D:4D (indicating high levels of testosterone in utero) may be correlated with enhanced left-hand performance. In right-handed children, high 2D:4D correlated with improved right-hand skill and low 2D:4D correlated with enhanced left-hand skill. Correlations were found to be similar for girls and for boys. Since low 2D:4D has been previously reported to be associ-ated with faster left-hand speed compared to right in Afro-Caribbean children with very low mean 2D:4D, the present finding in a Caucasian population with high mean 2D:4D suggests that a ten-dency of improved left-hand performance due to prenatal testosterone may be found across ethnic groups