Evolutionary theory dictates no such thing. It dictates just the opposite:
Get all you can as easily as you can.
And that takes freedom and individualism.
If you felt that humans should stick to the behaviors that are "natural" then I guess you will also have to say it is OK for men to impregnate as many women as they can get away with, abandon their wives once past child-bearing age, kill those from outside their tribe, kill children that aren't theirs, etc., etc.,
Realizing we have inherited certain instincts for base behavior (infanticide, voting Democratic)is not the same as giving in to them!