Long time lurker here, I've read posts in the past suggesting not to use main account on this subreddit due to the stigma associated with TRP, so I'm posting from this alt.

I had a 'showerthought' today which I pondered for a quite awhile. It's based mostly on the ideas of Gad Saad as expressed in his appearence on the Joe Rogan Experience.

Gad Saad crosses alot of interesting ideas, but one which he briefly touches on is the disparity between the price of pregnancy for males and females. In summary, in stone age time the price for a woman for choosing a poor mate was significantly higher than the price of a man choosing a poor mate.
Example, a small tribe, gets an attrative outside male visitor, lets assume for arguments sake the women in the tribe found this man attractive purely based on his physique and reproduced with him during his short stay. The man took off the next day, now the women who were impregnated are facing a horrible future, 9 months of pregnancy, with no provider to bring them the resources they need in this time. It's not inconceivable that the woman could die during childbirth without sufficient outside help. And after the birth the child would likewise lack a male parent bringing them the resources he/she needs, maybe the child would be left for the wolves.

If the gender roles were reversed, the tribe gets an attrative outside female visitor, a male impregnates her, the cost for the man is almost negligble, maybe the child and mother survives - maybe they dont, either way the cost is the same comparatively low cost, if he gets a descendant one would assume in an evolutionary perspective that this kind of behaviour would be fostered and nurtured.
This revelation in itself can explain why men are much more readily prepared to fuck women, and can decide whether or not they want to fuck a women within the first few seconds of seeing her. While women typically tend to take more time before making the same decision. It's a low cost decision for a man, and a high cost decision for a woman.
This is where shit tests come in, since the woman needs to know that her potentiale mate is reliable and resourceful, that he sticks around and helps her through the eventual pregnancy. If a woman in the aforementioned example, was able to gauge the reliability and resourcefullness of the man in the short timespan he was there by shit testing, she would be able to make a much more informed decision - which could save her life, a pregnancy, and alot of time.
What is the most common shit test of all time?
"How many sexual partners have you had?"
I'm not saying the stone age people would have the language capabilities to ask this in this same straightforward way. But if she could somehow gauge an answer to this question, she would have a really good gauge on whether or not this visitor was reliable or not, aswell as if he was competetively attractive. If the man had went from tribe to tribe fucking every woman in sight and leaving the next day, then naturally, he would not make a good mate for the woman - unless she had the resources necessary to take care of pregnancy and kid herself, which in stone age time I imagine would be highly unlikely - unlike modern times.
It seems that a woman who shit tests would make healthier decisions in stone age time, and if that is true then this could explain from an evolutionary perspective why shit testing is such an intrinsic part of modern relationships - It is fostered because its healthy for females to do so. This is as far as I got with this thought, I can't find any holes, so please tear this theory apart if you spot any flaws.