Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

Selective pressure is pressure exerted by the environment or man on a certain population through removal of the bearer of certain traits, e.g. an above-average large or below-average small individual, or by preventing such an individual from reproducing. Selective pressure need not always mean a negative effect on the bearer of undesirable forms of the trait, but can just as well consist in support for individuals with the desirable form of the trait.