A Sad Argument For Class Structure

We've all heard that America is a classless society. Nothing could be further from the truth; we are clearly delineated class-wise. I once heard that some of the brownstones in New York and New England were deceptive. When viewed from the outside, you see what appear to be multiple apartments. But, once you pass through the doors, you find that many of them, in middle class neighborhoods, hide large, single dwellings. That's how class works in this country - you don't see it at first. But it's there. Ask any minimum wage employee.
That's the crux of the problem. Some of my friends say that personal advancement is an individual issue. They take a very libertarian viewpoint, and they have that right. However, what they don't like to talk about is that in order for their ideal society to work, classes have to exist. For instance, you might have senior managers and owners on top, middle managers and specialists on another layer, and your average workers and then laborers near the bottom. Is there interclass movement? Probably, but it would be doubtful that someone from the bottom tier could make it any higher than a middle tier. The upper tiers would always set out to assure that they maintain that position.
Simply put, a rigid class structure would always come into being. Somehow, it's human nature. We want structure, our collective conscience needs it. Or so it seems.
I would argue that this is partially nature, but more than likely nurture. For all of our time on this planet, there have always been leaders and followers, rulers and servants. This need to follow and be ruled over is part of our psyche, coming up from the most primitive part of the brain, the area just above medulla oblongata, our reptilian ancestry. It is our animal selves that want this. We can't help but listen to it, against our own will.
Can the upper brain, the cerebral cortex, our higher selves, overcome this? I doubt that it can, not any time soon. This is not an argument for class based on biology, however. The one thing that truly separates us from the rest of nature is our intellect. It is simply too easy to listen to those animal instincts that were bred into us. We have, within ourselves, the ability to rise above these notions. Society forces us to accept things as they are, it seems, and the class structure would demand this of us.
We're still relatively young, both as a species and as society; it was barely a tick of the geologic clock ago that we were hunter-gatherers, trying to eke out a living. Biologically speaking, we've been a raving success.
Perhaps in time we can find another way to make society work. Until then, we just have to do the best we can and remember that we are all human, no matter our social position.