Mutation Accumulation Hypothesis

Mutation Accumulation Hypothesis

Type: Non adaptive hypothesis

Definition: “Aging” is due to the effects of harmful mutations, accumulated over evolutionary time, which manifest themselves at older ages when, in the wild, survivors are very few or absent and, consequently, selective forces are too weak to eliminate them

Proposers: Medawar 1952; Hamilton 1966; Edney & Gill 1968; Mueller 1987; Partridge & Barton 1993.

Theoretical arguments against the hypothesis:
Simple theoretical arguments contradict strongly Mutation Accumulation Hypothesis.

Empirical Evidence:
1) The existence of animals with negligible senescence is against the hypothesis.
2) The inverse correlation observed in the wild between extrinsic mortality rate and proportion of deaths due to intrinsic mortality is against the hypothesis.
3) The existence of mechanisms genetically determined and regulated limiting cell turnover and, therefore, lifespan is against the hypothesis.

Conclusion: Mutation Accumulation Hypothesis is strongly contradicted by theoretical arguments and by empirical evidence and is not a plausible hypothesis for aging.

References:
- Edney, E.B. & Gill, R.W. (1968) Evolution of senescence and specific longevity. Nature 220, 281-282. [PubMed] [Google Scholar]
- Hamilton, W.D. (1966) The moulding of senescence by natural selection. J. Theor. Biol. 12, 12-45. [PubMed] [Google Scholar]
- Medawar, P.B. (1952) An Unsolved Problem in Biology, H. K. Lewis, London. Reprinted in: Medawar, P.B. (1957) The Uniqueness of the Individual, Methuen, London. [Google Scholar]
- Mueller, L.D. (1987) Evolution of accelerated senescence in laboratory populations of Drosophila. Proc. Natl. Acad. Sci. USA 84, 1974-1977. [PubMed] [Google Scholar]
- Partridge, L. & Barton, N.H. (1993) Optimality, mutation and the evolution of ageing. Nature 362, 305-311. [PubMed] [Google Scholar]