Evidence for assortative mating on digit ratio (2D:4D), a biomarker for prenatal androgen exposure.
The second-to-fourth digit ratio (2D:4D) presents an anatomical sex difference in humans. On average, men tend to have lower 2D:4D compared with women. There is fairly strong evidence for a role of the 2D:4D ratio as a biomarker for the organizational (permanent) effects of prenatal testosterone on the brain and behaviour. Recently, an accumulating research programme has shown 2D:4D to be related to a multitude of sex-dependent, hormonally influenced biosocial traits and phenotypes which reach into the domains of ability, behaviour, fertility, health, personality and sexuality. This study investigated the degree of assortative mating (spousal similarity) in a sample of 239 native Austrian couples of parental or grandparental age, all of them having reproduced. Results included: (i) significant spousal correlations of +0.19 and +0.18 for right-hand and left-hand 2D:4D, respectively, and +0.24 for average 2D:4D; (ii) no assortative mating effect on the right-minus-left difference in 2D:4D; (iii) indications consistent with a possible generational decrease of spousal similarity in 2D:4D; (iv) a prevalence of couples with a lower right-hand 2D:4D observed in the husband compared with his wife; and (v) relations of spousal 2D:4D patterns to spousal age differences, such that matings of men with more male-typical trait expressions (namely, a generally low right-hand 2D:4D or showing a lower right-minus-left 2D:4D difference than their wives) implicated larger male-minus-female age differences, i.e. younger wives. It is argued that assortative mating on 2D:4D operates indirectly and may be mediated through the assortment on other, more perceptible, physical traits and psychological phenotypes that entertain associations with 2D:4D and are relevant for courtship and mate choice.
Voracek
Martin
M
University of Vienna, Austria.
Dressler
Stefan G
SG
Manning
John T
JT
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000728:Androgens; D000886:Anthropometry; D001317:Austria; D015415:Biomarkers; D005260:Female; D005385:Fingers / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D019655:Quantitative Trait, Heritable; D012016:Reference Values; D013739:Testosterone
D000728:Androgens; D015415:Biomarkers; D013739:Testosterone