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

The antagonistic pleiotropy theory goes even further than theory of reduction of the effectiveness of selection during the life of an individual. This theory assumes that a great many mutations have pleiotropic effect, i.e. that they have a number of contradictory manifestations from the viewpoint of the viability of the individual. These manifestations of a certain mutation can sometimes occur simultaneously; however, they also can occur in different phases of the life cycle of the individual. If a certain mutation has a favorable effect on the viability at an early stage in the life cycle and simultaneously a negative effect at a later stage in the cycle, it will become fixed in the population because, as was already explained in the previous section, the effectiveness of selection is greater in the early stages of the life cycle of an individual. It follows from this theory (Pedersen 1995) that the deterioration in viability during ageing is caused by the manifestations of accumulated mutations with antagonistic effects, to be more exact, by those that provide a selection advantage for a younger individual and simultaneously a disadvantage for an older individual (Fig. XII.7) {11593}. A mutation increasing the ability to regenerate tissue in a young individual which must almost necessarily simultaneously increase the risk of cancer in an older individual is a typical example.