Your theory about the origin of aggressiveness puts more weight on the genes; mine puts more weight on the culture.

You do know that this is a controversial topic since at least 1963 when Konrad Lorentz published his On Aggression, right? If you want to talk about theories it's a good habit to be aware of existing literature :-/

This is a good and interesting discussion, finally. Upvoted.

First of all - my main point is that aggressiveness is not simply a bad thing. It is certainly dangerous. It is arguable whether it is a net negative, but it also has good aspects, or, to put differently, it is caused by things that have other effects and some of those are good, and removing the roots of aggressiveness would also remove them.

Second - aggressiveness is not really well defined term. Let's see two examples. Let's look at a fair and equal fight, duel-like, even with weight classes like boxing, and obviously a voluntary one. The other example is simply beating up someone who is defenseless, a victim, out of hatred.

The two things are IMHO very different and hardly ever connected. The second type aims to cause harm, the weaker and more defenseless the victim is the better. The first type looks for challenge: in the first type of encounter if the opponent is defensless or bad at defending himself the whole thing becomes boring and pointless.

So the difference is rather huge and it is not the same thing. The issue is, humanist intellectuals who hate both types tend to conflate them. I am not sure you do. I am sure Erich Fromm did conflate them in The Anatomy of Human Destructiveness which is a textbook case of how to miss this kind of point.

We really need different terms for this, as I obviously endorse only of the first. The first is more of a more intense version of competition and dominance, really a more intense form of volleyball. The second is something much more evil.

The first is lot like challenging each other to a test: if I tried to do the second on you, could you defend yourself? The second is largely outgroup, it is a destroy-the-enemy ethos. The first is closer to an in-group dominance fight, more of a let's see who is boss around here. (At this point I admit the confusion that I modeled the first type, but between out-groups, but what else can I do? )

I would not collapse in laughter. A form of communist puritanism has a certain appeal to me, but probably for the wrong reasons: it channels status-seeking to more excitingly aggressive forms. It is, quite literally, Sparta.

In the utopia where I'm absolute dictator, liquors are illegal.

Well, at least you're being internally consistent.