Summary: Hypergamy might be evolution's way of keeping humans lean and fit on a macro scale.

I have just recently started turning this over in my head. I'm not absolutely sold on the idea, but thought it was worth considering and that you all might have some thoughts as well.

TRP talks quite about about hypergamy and how it will lead to a decline, if not fall, if not outright collapse of society. Some seem poised to enjoy the ride, others seems to be in various amounts of anguish over the prospect.

What if one of hypergamy's main utilities is to create such outcomes? You either grow or die. But, you can't grow forever, if you try, you'll just stagnate. Hypergamy might not only be designed to bring about the end of a society after that society has made its major progressive contributions to people, but it might just do so in a way meant to carry through the process all of the best genes while winnowing out all of the lesser genes.

First, a bit of history. Most people are aware of the medieval dark ages. Rome, the uncontested high point of human achieve up to that point collapsed and everything went to hell. It didn't collapse over night. But it wasn't slow either. It fell fairly hard and dramatically. It fell after taking all aspects of human thought to new levels. It also fell after prolonged social indulgence marked in huge part by highly promiscuous women. That promiscuity was fought, but promiscuity won. Society as a whole lost all of the features that had originally allowed Roman society to succeed. Rome isn't isolated.

Before Rome, Greek culture had a similar, but much smaller on scale, rise and fall. Prior to Greeks was Persians, prior to Persians was Babylonia. About 800-1000 to all that the Mycanean Golden Age collapsed bringing in a dark ages of greater antiquity.

Egypt and China, both relatively isolated cultures (Egypt surrounded on all sides by Ocean or extreme Dessert, except one small land bridge in the Sinai) had periods of extreme highs followed by rapid declines, with each high precipitated by loosening women and cultural mores.

This might be a necessary biological curtailing mechanism. Humans seems to have cobbled together several survival mechanisms, incorporating both quantity and quality reproductive strategies along with secondary resources such as society and housing structures, migration and rapid adaptability. Each of these are survival/reproductive strategies used by lesser animals, but it seems as we alone have all of them readily at our fingertips. But this could pose problems.

Our reproductive capacities mean we risk unsustainable numbers and genetic stagnation. One man-one women allows high reproduction and high paternal investment. That should result in a lot of numbers, the quality going up AND the accumulation of significant resource availability. As we see in the world around us that is highly successful but also not remotely sustainable. So, how do humans get around this?

Remove the supports that allowed the numbers and resources to accumulate. While doing that also allow the women to mate exclusively, or almost exclusively, with only the most genetically fit males and raise the resulting offspring with the reserve resources. The results might very well be a huge die off of the population but one where all of the competing offspring come from only, or almost only, the most fit males.

That would have great results, it's like the body storing energy right before a growth spurt. It will accumulate energy reserves before depleting them all to get through the next growth cycle. What's left is stronger and leaner than before. Likewise, such cycles would consistently see all of the weaker genes competed out of the pool in ever dwindling numbers until only a small group of the very best-due to the prior generation's promiscuity/exclusive reproduction with the best males-was left. Then, they'd be ready to restart the whole process having removed all of the weaker links and dead weights. It's interesting to note that each time in history it happened, the next generation to arise, once it finally did, surpassed everything that came before, even the prior golden ages.

TL/DR: Hypergamy is brutal but possibly necessary process of gene distillation.