Selection, artificial and natural - a wonderful concept.
Those serious-minded jihadis out in the Caliphate raise psychopathy to new levels. I expect the prospects of joining them in their exciting campaign of mutilation, amputation, beheading, FGM and crucifixion will likely prove more attractive to UK psychopaths than the average religiously-observant regular guy who has a bit of empathy. And so the pit is dug deeper.
A completely different example of selection. Nature used to select women with an interest in sex (hard to believe, perhaps, but how could it be otherwise?).
These days, in advanced countries with contraception, selection is for women who actively like children (or are too unconscientious or unmotivated to use birth control). Interesting to speculate on the psychological and social consequences in future generations.