The second-to-fourth digit ratio (2D:4D) is a sexually dimorphic somatic trait and has been proposed as a biomarker
for the organizational, i.e., permanent, effects of prenatal testosterone on the human brain. Accordingly, recent research
has related 2D:4D to a variety of sex-dependent, hormonally influenced traits and phenotypes. The geographical variation
in typical 2D:4D is marked and presently poorly understood. This study presents the first investigation into the
2D:4D ratio in a Baltic country. A contemporary sample of 109 Lithuanian men and women was compared with data
from a historical sample of 100 Lithuanian men and women, collected and published in the 1880s and rediscovered only
now. The findings included the following lines of evidence: (i) seen in an international perspective, the average 2D:4D in
Lithuania is low; (ii) there was a sex difference in 2D:4D in the expected direction in both samples; (iii) a previously adduced
hypothesis of an association of lighter eye and hair color with higher, i.e., more feminized, 2D:4D received no support
in both samples; and (iv) the average 2D:4D in the contemporary sample was higher than in the historical sample.
In view of a hypothesized increase in 2D:4D in modern populations, owing to increased environmental levels of endocrine
disruptors such as xenoestrogens, this latter finding appears to be of particular notice. However, because finger-
-length measurement methods differed across the samples, it cannot be safely ruled out that the apparent time trend in
Lithuanian 2D:4D in truth is an artifact. The puzzling geographical pattern seen in the 2D:4D ratio and the question of
possible time trends therein deserve further investigations
