A crucial task of Evolutionary Psychology 101 is to learn the difference between proximate and ultimate causation. You can’t really understand anything important about evolutionary psychology, and thus you can’t really understand much of anything important about family and civilization, unless you understand this basic distinction. Let’s take two examples where proximate and ultimate causation are confused:
(1) “Women prefer alpha males over beta males because it used to be the case that they would have more surviving offspring if protected by powerful alphas. But this is no longer the case. Today a woman can have just as many offspring with a beta as with an alpha. Therefore, with enough exhortation and instruction we can teach women to stop prefering alphas over betas.”
(2) “Men get jealous and engage in mate-guarding behaviors, and decide how much time and resources to invest in their children based on these emotions, because men need to be confident of paternity in order for their genes to succeed. But today we have DNA tests, so men need no longer worry about any of this. It causes no harm for a wife to commit adultery as long as the real biological father is identified and made to pay to raise the child.” (Michelle Langley’s theory).
“Paternity confidence” is simply a shorthand about ultimate causation, that is about why certain innate male behaviors evolved. In other words, it’s a statement about under what evolutionary pressures of genetic selection the behaviors evolved. In this case, the longhand is a formal model of differential genetic propagation that shows how cues and resulting behaviors of men in the evolutionary environment of adaptation (usually considered to be a hunter-gatherer culture) evolved to increase the probability that they invested more in their own genetic children and less in others’, thus increasing the propagation of the genes coding for this behavior.
The proximate behaviors, i.e. the systems of recognition and behavior response or propensity that actually evolved, are not about intellectual understanding or knowledge of paternity, they are about the man observing how his mate behaves and treating her and her children accordingly. Possible cues include — does she hang around with other women or other men? Does she disappear unexpectedly or often fail to have an alibi? What stories does he hear about what she does when he is absent? Does she act towards him in a loving way? Do the children look more like him or like the stud neighbor she’s been seen making eyes at? What was her sexual behavior like before he met her? All proximate signals that relate to the ultimate (and quite implicit) genetic “goal” of paternity confidence, and thus about how much, if any, further time and resources he should invest in his children and in his mate after he has had sex with her. The cues that evolved are innate cues that men still respond strongly to despite any paternity tests that deal with the original ultimate reason why these proximate innate behaviors evolved.
If you didn’t follow all that, let’s take an example more commonly discussed in these parts: women still tend to seek men with (among other things) greater wealth and power, since in the evolutionary environment of adaption (but not necessarily now) a wealthier and more powerful mate led to more surviving offspring. It does not follow that if women today learn and believe the fact that today they can have as many surviving offspring with a beta male as an alpha, that they can be convinced to stop preferring alphas. To think so is to confuse ultimate with proximate causation. So now that you understand ultimate vs. proximate causation, go back and read the preceeding paragraphs.
Back to paternity testing, it is possible that one of the proximate cues for paternity confidence does happen to what the man learns via communication (whether from people telling him how much the baby looks like him, or from a paternity test, or otherwise). But in the evolutionary environment these communications could easily be misleading, and were unverifiable, so I heavily doubt that any mere communications, whether in the form of paternity tests or otherwise, have any substantial positive impact on the emotional attitudes and resulting behaviors that evolved to assess and act on paternity confidence. A paternity test can convince him intellectually, but not emotionally, that the children really are his. To convince him emotionally requires the traditional virtues of women that most of today’s Western women have forgotten.
The Michelle Langley theory that Devlin criticizes in “Rotating Polyandry — and Its Enforcers”, that paternity testing now allows women to live out their hypergamistic fantasies of adultery with more alpha males because their husbands can DNA test the kids and thus no longer have a reason to get jealous, thus doesn’t work any better than the idea that beta men can simply point out to women that they can have as many surviving offspring with betas as with alphas, and thereby convince them to start prefering betas. Both of these lines of reasoning confuse ultimate and proximate causation.