I don't look at it in the context of up and down, nor the idea that perfection is a target. Even if such a thing could be achieved, it would only be perfection for a moment, because the environment would change, and therefore, the perfection lost.
I think more in terms of adaptation. We may look at extinct species and conclude that better species came along to replace them, but that would not be accurate. In fact, the extinct species at one time was the best equipped to deal with its environment, and the later species may not have survived in the older environment. Adaptation. The species best adapted to the environment will be most successful. If the environment changes, and the species cannot adapt, it will go extinct. It's not a question of better or targets, it simply is what it is.