In biology, negative selection is artificial selection in which negative, rather than positive traits of a species are selected. It is generally not desirable, but caused by bad management, wherein humans eat the best plants or animals they have, leading to worse and worse stock; it occurred frequently, for example, in primitive beekeeping.
A simplistic definition of natural selection would say it can never give rise to negative selection. However with a small population and the non-deterministic nature of inheritance of traits, it is possible though unlikely.
Some proponents of eugenics argue that medicine and other technological, societal, and cultural practices cause negative selection in humans. According to them, man as a species manifests more and more negative traits as a result of this.
In politics, negative selection is a process that occurs in rigid hierarchies, most notably dictatorships.
The person on the top of the hierarchy, wishing to remain in power forever, chooses his associates with the prime criterion of incompetence - they must not be competent enough to remove him from power. The associates do the same with those below them in the hierarchy, and the hierarchy is progressively filled with more and more incompetent people.
If the dictator sees that he is threathened nonetheless, he will remove those that threaten him from their positions - "purge" the hierarchy.
Emptied positions in the hierarchy are normally filled with people from below - those who were less competent than their previous masters.
So, over the course of time, the hierarchy becomes less and less effective. As this happens relatively often, once when the dictator dies, or is removed by some external influence, what remains is a grossly ineffective hierarchy.
It is thought that this is one of the major factors responsible for problems of the former communist countries during their transition.
