Our study demonstrated that women with lower digit ratios (2D:4D) for both hands tend to suffer migraine and TTH.
It will come in handy when, at the end of the trip, you check your bank account and see a lower digit due to flight disruption expenses.
The lower digit ratio, which is indicative of exposure to higher prenatal testosterone and lower prenatal estrogen, was associated with Migraine and TTH in women [11].
Other work has suggested that masculinization is associated with lower digit ratios in lab mice.
A second possible explanation is that higher exercise rates are in fact more "masculinized," but that lower digit ratios do not indicate greater masculinization in these mice.
Lower digit ratios are believed to indicate increased prenatal testosterone exposure, and are associated with more masculinized behavior across a range of traits.
Both of these latter two studies found males to have significantly lower digit ratios than females, albeit on different limbs: right rear in [17] and left rear in [18].
Lower digit ratios are associated with greater physical fitness or athletic competitiveness in men and women [5] [10], but mouse strains with higher digit ratios tend (p = 0.058) to show higher daily activity levels (measured by the total number of beam breaks per day in an individual live-in cage) [23].
On balance, the lack of any sex effect in that direction suggests strongly that if digit ratio indicates masculinization, then the high-running lines are the more feminized, and the possibility that lower digit ratios are more masculinized is a poor candidate explanation for our results.
Contrary to the trend noted in [19] —where males tended to have larger 2D∶4D than females in strains where the mean ratio was large and lower digit ratios than females in strains where the mean ratio was small— we found no significant relationship between a strain's mean digit ratio with the direction and magnitude of the difference between the sexes (r(18) = 0.30, p = 0.20).
