The word murd murder implies an immoral motive, not just the act of killing. If you believe that a specific act of killing is in self defense, or in the defense of your family, community or nation, then it is not murder.
Authorities seldom tell people to commit murder. They tell them what is necessary for defense.
FWIW, you're touching on a different topic here, which is the moral implications of something like the theory of evolution. Can one really make a positive statement about the "moral propriety" of killing -- whether as murder or self-defense -- when the moral implications of evolution tend to support utilitarian principles?
Yeah, it's a topic for a different day, but since you'd already sorta brought it up...
Yes. That's why I distinguished between murder and killing.