Digit ratio (2D:4D) in Lithuania once and now: testing for sex differences, relations with eye and hair color, and a possible secular change.
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.
Voracek
Martin
M
Department of Basic Psychological Research, School of Psychology, University of Vienna, Vienna, Austria. martin.voracek@univie.ac.at
Bagdonas
Albinas
A
Dressler
Stefan G
SG
D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers; D001837:Body Weights and Measures / Q000266:history / Q000639:trends; D005127:Eye Color / Q000502:physiology*; D005260:Female; D005385:Fingers / Q000033:anatomy & histology*; D006200:Hair Color / Q000502:physiology*; D049672:History, 19th Century; D006801:Humans; D008097:Lithuania; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012727:Sex Characteristics
D015415:Biomarkers