What would be the harm?

[The Grand Nudger]

Exactly, jorm.  Exactly.  It's very advantageous to me from the standpoint of evolutionary biology (hell, it's advantageous to the species), and yet, as a moral proposition....wrong.  Is that not out-thinking our biology, or unmooring our moral propositions from an evolutionary underpinning that may not describe "the good" only the "good-for"?

Oh, gotcha.  I thought you were suggesting burning out our neighbors was a moral proposition.  Now that I understand, allow me to object to what you meant.  As an individual act, burning out my neighbors has advantages.  However if I further a world in which people are allowed to burn each other out ad libitum, then that threatens the security and safety of me and mine.  I have a definite biological interest in the safety of me and mine, so I have a biological motive for forbidding such things, and refraining from them for fear that might prompt others to do likewise to me, regardless of how advantageous it might be for me to act thus otherwise.  So, no, this is not an example where morals are in contradiction to evolved needs and biology.  The problem is the lack of universalizability of the act.  An act which is in accord with my interests can quickly become contrary to my interests if universalizing said behavior would impinge upon the survivability of me and my genes.  This is why most moral frameworks, such as Kant's, have universalizability as a key feature.

None of that matters to evolution.  Aggressive and lethal competition for resources benefits the individual who prevails and weeds out those lesser genetics from the pool.

You may have a definite interest, but to call it a definite biological interest is to subtly conflate that with the interests of evolutionary biology, which don;t give a shit about you and your interests.  Additionally, while you posit that you have such a rational self interest..if you really were the biggest and the baddest in the land your rational self interest would rationally lead you to burn out the weaklings.

In all of this, remember, that by mooring your moral propositions (not your apparatus, your moral propositions themselves) to the whims of evolutionary biology or survival you are explicitly tanking the meaningful objectivity of a moral system in ethical terms.  You are setting it up to be knocked down, and with ease-

-naturalistic fallacy.

If that which is good is, more properly, that which is good for survival, it is an instrumental good, and not an intrinsic good. It is not a matter of the fact x, but some other fact, y, to which x is applied as leverage. The good, rather than the good for, could very well be (and often is) z. It may be natural to do x, because of y, but that won't change the fact that it is z, and not x or y which is good (obviously, supposing that there is such a fact)...and that the fact z is that x is bad.