Thing about evolution is that physically speaking, it doesn't really exist anymore in humans - if you have any evidence that it does, feel free to prove me wrong. Mental evolution is where it's all at, in my opinion. Whereas being detached or misanthropic as many serial killers are could be considered to be could be an advantage with regards to ensuring the continuation of your own genetics, it also swings the other way. You could argue that empathy is an evolutionary advantage for the human race as a whole, a person may put themselves in danger for the 'greater good' of mankind (though really, the good of mankind is non-existent), which would help improve the survival of the human race as a whole, but not ensure their genetics continue on through generations. Whilst on the topic of evolution I'd like to point out an unpopular opinion of mine - if serial killers are well adapted creatures, then suicidal people are maladaptive. Since In my opinion I believe that all evolution happens within the mind now, this would mean that suicidal depression is a way of filtering out those who are perhaps not mentally strong enough for our society. Such as fight to the death scenarios - would you be able to defend yourself if a serial killer was to approach you? More importantly would you want to, or rather, have the guts to? That is the new natural selection.