David Brin on the Neolithic bottleneck

In Bio-Scientific problems and quandaries David Brin writes among other things:
“But are we still evolving? Between 9000 and 7000 years ago, there appears to have been a plummet in genetic diversity among human males, in what’s called the ‘Neolithic bottleneck.’ An undergrad is now credited with coming up with an explanation. Heck the surficial hypothesis is obvious – that across that time, combative males prevented other males from breeding. But apparently this study's methodology for using available data to exclude other hypotheses was very clever.  “Zeng surmised that intense warfare between patrilineal clans killed off so many men, only one was left for every 17 women.”

This should come as no surprise. Historical accounts show numerous societies doing this, even in historical times. Polynesia, for example, and the Mayan states. All of the adult males in a valley or on an island might be wiped out and replaced by the invaders who were likely related. (Indeed, I wonder that the authors of this study haven't zeroed in on those more recent episodes.) Nearly all of us are descended from the harems of the fierce men who won these struggles... helping to explain the "quirks" or unpleasant proclivities we see in many modern males, traits that are unsuitable for civilized living. Indeed, if this cycle were allowed to continue, it might help to explain the “Fermi Paradox” of why we don’t see high, alien civilizations.”