I tried to post this question yesterday, but it was removed. The mods asked me to submit a revised question more in line with the subreddit's guidelines. The mods were nice about it. Let's have a round of applause for the mods.

Here's an article that of explains the Y Chromosome Bottleneck. Unfortunately, I don't completely understand the article.

As far as I can tell, in many parts of the world, between 7000 and 5000 years ago, only one male in twenty (give or take) actually reproduced.

Do historians have any evidence that helps us understand what really happened? As I imagine it, it seems like bands or armies of closely related males would invade and dominate a certain region, monopolize all the women, possibly in some harem-like system, and then enslave, castrate or kill the local males. The sons and grandsons of the dominant males would then go on to father subsequent generations of children.

I'm guessing the invaders couldn't kill all the non-dominant males because they would be needed for farming and herding, to produce enough food for the women, children and invading males. However, I'm only guessing. Do historians have any evidence that sheds light on this?

The article I cited above, explains why this system disappeared about 5000 years ago, but the explanation is hard to understand. Can historians clarify it?

I wonder if the system disappeared entirely. Are more recent systems of severe restriction of female sexual freedom, harems, eunuchs, and male slaves or peasants, modern remnants of this ancient phenomenon?