Laurence J. Peter and James Hull defined The Peter Principle: “In a hierarchically structured administration, people tend to be promoted up to their level of incompetence.”
I think that's fairly well understood, but what does it look like if we frame it in an evolutionary perspective?
The evolutionary generalization of the principle is less pessimistic in its implications, since evolution lacks the bureaucratic inertia that pushes and maintains people in an unfit position. But what will certainly remain is that systems confronted by evolutionary problems will quickly tackle the easy ones, but tend to get stuck in the difficult ones. The better (more fit, smarter, more competent, more adaptive) a system is, the more quickly it will solve all the easy problems, but the more difficult the problem will be it finally gets stuck in. Getting stuck here does not mean “being unfit”, it just means having reached the limit of one's competence, and thus having great difficulty advancing further. This explains why even the most complex and adaptive species (such as ourselves, humans) are always still “struggling for survival” in their niches as energetically as are the most primitive organisms such as bacteria. If ever a species would get control over all its evolutionary problems, then the “Red Queen Principle” would make sure that new, more complex problems would arise, so that the species would continue to balance on the border of its domain of incompetence. In conclusion, the generalized Peter principle states that in evolution systems tend to develop up to the limit of their adaptive competence.