One man can impregnate many women.
A friend of mine hunts Mule deer. He only hunts bucks because it only takes a few bucks to keep the population going. The females are not as expendable, and killing too many will hurt the deer population.
The extinction of the species isn't really a pressing concern at the moment, and the only kind of war that's likely to make it so won't be fought with soldiers...
Incidentally, our social expectation of (relatively) monogamous child-bearing relationships is a rather neat illustration of the suppression of natural instincts for the benefit of society.
Survival of the species is paramount, instinctively. Men protecting women is part of that instinct. For many of us, we have no way (or desire) to change this human instinct.
I can understand it being difficult, and have already set out my arguments for why I think one
should desire to change this instinct.
It's an interesting subject. I see it as a case of my idealism being confronted by my biological instinct. We humans are a strange hybrid of human idealism and animal instinct, and the human condition is one of perpetual inner conflict, as a result. Our "animal" nature would lead us to behave one way, while our "human" natures would impel us to behave another. This inner conflict has been reflected in our philosophy, religions, and sociology throughout the whole history of human culture.
I guess I chose the position that I have regarding this particular issue only because I see warfare as an expression of our animal natures more than of our human idealism. So I side with my animal instincts in deciding the case. Whereas in situations that would allow for a more contemplative study of the matter, I would likely side with my more idealistic human instincts.
That's an interesting way of looking at it, and certainly in a combat situation erring toward the 'animal' side might give you a bit of an edge, but I think that when you fail to allow your 'human' side to govern your actions - even temporarily - there's a real risk of embracing utter savagery.
One of my favourite passages of the
Tao Te Ching, which I believe I've quoted before on this site, puts it quite well:
Lao Tzu said:
Weapons are the tools of violence;
all decent men detest them.
Weapons are the tools of fear;
a decent man will avoid them
except in the direst necessity
and, if compelled, will use them
only with the utmost restraint.
Peace is his highest value.
If the peace has been shattered,
how can he be content?
His enemies are not demons,
but human beings like himself.
He doesn't wish them personal harm.
Nor does he rejoice in victory.
How could he rejoice in victory
and delight in the slaughter of men?
He enters a battle gravely,
with sorrow and with great compassion,
as if he were attending a funeral.
Our 'animal' side would have us hate our enemies and take pleasure in their suffering - the biological, hormonal response to conflict, the 'killer instinct', often manifests in a sort of excitement and exuberance - but it is of the utmost importance that we suppress this and instead grieve for those we harm, otherwise we actively betray everything our 'human' side stands for.
In the same way, there is an animal instinct in some men to prioritise women in times of hardship. As subtle as the negative effects of this on our idealism are, I do believe they exist, and once again I think this is reason enough to try to suppress and eliminate it.
Just my opinion.