That said, chiefalchemist is jumping to conclusions not supported by the data in the papers when he offers his conjectures on violence etc. The only thing we can really conclude with authority based on this data is that whatever happened, more of it happened in europe and the mideast.
With that said, let me rephrase then...the "rise" of the "violence gene profile":
1) Was more effective in some parts of the world then in others.
2) That profile is still with us today. Perhaps not as dominant but none rhe less not gone.
3) We may think we're a peace loving species but our gene pool says other wise.
Again, yesterday's "winning effort" is today's murder. Today's mental health issues arw yesterday's hero (e.g., an unfiltered willingness to kill).
We can talk about being rational, intelligent, etc. but the fact is we still have a gene pool that historically says otherwise.
this replacement (sedentary agriculturalists killing/pushing out hunter-gatherers) happened everywhere in the world, not just 'white western europe'