Women are disposed to cheat sometimes

In the <previous post> I started searching for uniquely female tendencies that were adaptive in our environment of evolutionary adaptation but are not adaptive or moral today. I suggested a reluctance to give babies up for adoption.

Here's another one: a tendency to cheat so that a baby is fathered by a "better" man but is presented to her husband as his to raise and care for.

For some context, let me emphasize that male-specific bad behavior dwarfs anything mentioned here or in the previous post. I'm not thinking in war-of-the-sexes terms. But I think finding such cases is interesting in its own right, and might possibly give some perspective on male misbehavior.

The background of this is that in most mammals, the male provides nothing but sperm. The female chooses among competing males for the one she thinks is "best" and mates with him. His good genes make it more likely that the offspring will be successful and leave descendants which include her genes. In humans, males do help raise children, and women have long-term commitments to individual men. The men with the best genes are in short supply and are likely taken by some other woman, but it is worth it to her to have a husband with just average genes who supports her children. However, a woman could get the best of both worlds if she sneaks off to have an affair with the best man (call him the "sexiest man") who fathers her child, while the cuckolded husband thinks it is his and helps her raise it. A prediction of the theory is that actual women seeking affairs outside marriage will most often choose men who are above their husband in sexiness. This and other aspects of human sexuality from an evo psych point of view are laid out in more detail in <this excellent TEDx talk>.

It's notable that in some birds the same basic situation holds, and <birds cheat>.

Something on the order of 1-5% of children in today's world are raised by a male parent who thinks he is the biological father but is not. One reason this might happen is if the woman became pregnant by rape and understandably decided not to tell her husband. Or the timing of the rape might have been such that she is uncertain whether the husband is the father or not. I suspect these cases are actually quite rare. They would not qualify as bad behavior in the way that choosing to cheat would be.

It is possible that a woman says to herself, "I'm going to get that really sexy man to father my child, and dupe my husband and he'll help raise it, bwa-ha-ha!" That would be not very nice at all. That would deserve the name "paternity fraud". A few women do it.

But evolution doesn't tend to work in such an open and obvious fashion. One reason is that it's better if she loves her husband (putting up with his weaknesses while he does help raise the children), and better if her husband believes this, and both actuality and perception are easier to maintain if she is not deliberately deceiving him.

We would expect evolution to design it to be more an impulsive decision, perhaps putting herself in the path of the sexiest man, and being carried away with the passion of the moment to accept his advances. She might feel guilty for the liaison. She might feel especially guilty if she has reason to think she got pregnant from such an encounter -- and thus have reason not to dwell on such possibilities. But it would still be an adaptive advantage in the environment we evolved in.

There was an exciting line of research suggesting that women were https://en.wikipedia.org/wiki/Ovulatory_shift_hypothesis. Some feminists objected, though I saw no reason to think these findings would be harmful to women. The latest word is that this https://slate.com/technology/2018/10/ovulation-research-women-replication-crisis.html. But whether extramarital sex is coordinated with ovulatory phase or not, some babies are still conceived outside of marriage and raised by cuckolded men.

Such opportunities might not arise very often for women in earlier times or now -- a discreet, high-status man nearby willing to have sex with low probability of detection. Even with an opportunity, just how often women will let themselves give in to this innate tendency would presumably vary with time and place. When definitive paternity identification became possible with DNA testing -- or even when people understood it was a likely future development -- we might expect women to be more cautious, suppressing this evolutionary tendency. On the other hand, women today also might not feel the need to suppress if they know they are on reliable contraception.

Of course the sexiest man also had a role in such cuckolding. But evolution doesn't expect him to refuse an opportunity to mate with a willing partner.

What about husbands who cheat? It is not a parallel case in evolutionary terms. A husband who has affairs does not upset his wife's genetic interest as long as he doesn't leave her. It's of no concern to her in evolutionary terms if her husband fathers children with some other woman. This is why polygamy is a stable arrangement, however much we disapprove of it today given our modern morality, as long as the man has resources to support all his wives and children.

So, it's not much, but a tendency to cheat does look like one instance of evolution predisposing women to do something that is not in line with our modern notions of morality. Evo psych suggests that men are programmed with a tendency to do more immoral things and more often.