If you're serious about "silently judging women with low digit ratios", do you know what the link between digit ratio and "sluttiness" is? It's not clear to me from the OP's first link (http://m.rsbl.royalsocietypublishing.org/content/11/2/20140977.full.pdf).

Quoting from the OP's first link (some parts don't copy and paste correctly):

From the "Methods" section:

SOI-R data were collected from British and North American Caucasian participants using an online questionnaire [18]. These comprised 134 male and 186 female British participants and 68 male and 187 female North American participants (ages 18– 63, mean ¼ 24.7, s.d. ¼ 7.9). To assess participants’ preferred mating strategy (sociosexual orientation), questions forming the ‘attitude’ and ‘desire’ subscales of the SOI-R were used [3,13].

The following paragraph:

Data on 2D : 4D ratios were previously collected from righthand photocopies in a large-scale study of a British Caucasian population (n ¼ 1314, 572 males, 742 females).

So it seems that the SOI-R data and the 2D:4D data were taken from different groups of people.

From the "Results" section:

The likelihood ratio x2 tests confirm that the British and North American male and female sociosexuality datasets each have an underlying bimodal distribution (table 1).

Okay.

Later:

While the x2 tests confirm that the male 2D : 4D data also have an underlying bimodal distribution, the female data just fail to reach statistical significance ( p ¼ 0.079). Nonetheless, modelling still supports the existence of two underlying phenotypes for both sexes (table 2), with low 2D : 4D males making up a larger proportion of the male distribution, and the female 2D : 4D phenotypes being more evenly distributed (figure 2).

Okay.

But where is the link between sociosexuality and 2D:4D? Is it even possible to link them considering that the sociosexuality data and the 2D:4D data seem to come from different groups of people?

What if they also found that some other trait, say hypothetically how much people liked broccoli had an underlying bimodal distribution? Would it mean there was some kind of link between how much a person likes broccoli and how promiscuous they are?

Am I missing something?

Also a separate but possibly relevant issue:

The statistical method used here assumes that underlying mixture distributions are normally distributed and does not rule out the possibility that the two phenotypes are skewed or represent two separate peaks on a single underlying distribution. Unfortunately, it is not possible to investigate alternative statistical distributions: the near-infinite number of possible permutations and combinations involved makes statistical analysis impossible. These methods, however, are still robust enough to point to the existence of alternative mating phenotypes in both sexes, and it is likely that these have distributions across the phenotypic continuum (in all likelihood reflecting the fact that they are predispositions rather than categorical types). More importantly, which of these alternatives is biologically the case does not affect our claim that statistical analysis of three separate datasets reveals that each sex seems to exhibit two different phenotypes in roughly equal proportions.