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The somatic mutation theory of ageing states that accumulation of mutations in somatic cells is the primary cause of aging. A comparison of somatic mutation rate across several mammal species found that the total number of accumulated mutations at the end of lifespan was roughly equal across a broad range of lifespans. [16]
Somatic mutations accumulate within an organism's cells as it ages and with each round of cell division; the role of somatic mutations in the development of cancer is well established, and the accumulation of somatic mutations is implicated in the biology of aging. [4]
In populations where extrinsic mortality is low, the drop in reproductive probability after maturity is less severe than in other cases. The mutation accumulation theory therefore predicts that such populations would evolve delayed senescence. [5] One such example of this scenario can be seen when comparing birds to organisms of equivalent size.
In biogerontology, the disposable soma theory of aging states that organisms age due to an evolutionary trade-off between growth, reproduction, and DNA repair maintenance. [1] Formulated by British biologist Thomas Kirkwood , the disposable soma theory explains that an organism only has a limited amount of resources that it can allocate to its ...
Human somatic variations are somatic mutations (mutations that occur in somatic cells) both at early stages of development and in adult cells. These variations can lead either to pathogenic phenotypes or not, even if their function in healthy conditions is not completely clear yet.
Somatic hypermutation (or SHM) is a cellular mechanism by which the immune system adapts to the new foreign elements that confront it (e.g. microbes).A major component of the process of affinity maturation, SHM diversifies B cell receptors used to recognize foreign elements and allows the immune system to adapt its response to new threats during the lifetime of an organism. [1]
The cellularity of the bone marrow does decrease with age and can be usually calculated by the formula 100-age, and this seems consistent with a stem cell theory of aging. [18] A dog study published by Zaucha J.M, Yu C. and Mathioudakis G., et al. also shows evidence against the stem cell theory. Experimental comparison of the engraftment ...
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