Disposable Soma Theory

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The disposable soma theory (soma = 'human body'; English disposable soma = " disposable body ") is a theory put forward in 1977 by the English biologist Tom Kirkwood on the evolution of aging .

description

The aging is one of the least understood phenomena on biology. Various theories have been put forward to explain this phenomenon. One of them is Thomas Kirkwood's Disposable Soma Theory.

The energy resources for an organism are always limited. Different phases of life compete for these scarce resources. Compromises have to be made in the distribution of energy resources. The energy is used for metabolism, reproduction and for repair and maintenance of the body (physical integrity). According to Kirkwood, an organism can either invest in the longevity of the body ( soma ) or in a high rate of reproduction. Both processes compete for the nutrients absorbed. What one process absorbs is no longer available to the other. There is an energetic-physiological conflict ( trade-off ) between investing in fertility on the one hand and securing physical integrity on the other. Because of this energetic dilemma, an organism invests only so much and only so long energy in maintaining the soma that survival and reproduction are assured. Any investment going beyond that would be missing in the reproduction, which would reduce the overall success of the reproduction. However, this would be subject to a negative selection . The tradeoff in energy allocation for repair functions results in the body gradually deteriorating as it ages.

The term Disposable Soma ( disposable body ) was formed in analogy to disposable / single-use products, which, since they are only used for a limited time, are not very stable.

reception

The disposable soma theory tries to explain the aging process of organisms on the basis of the theory of evolution . For gene transmission, investing in reproductive strategies can be more economical than investing in longevity strategies. The body of an organism and that of humans is optimized for procreation (reproduction) and the rearing of the offspring. Aging, illness and death are side effects. Health in old age and longevity are not goals of evolution. When reproduction is complete and the offspring is independent, there is no evolutionary need for the organism to survive. The body ( soma ) is thus available .

The theory has some weaknesses. For example, a drastic reduction in energy supply would have a negative effect on both reproduction and the lifespan of an organism. In a large number of experiments with model organisms and restricted feeding ( calorie restriction or intermittent fasting ), a significant decrease in the fertility of the test animals was observed, but also a significant increase in their life expectancy.

literature

Individual evidence

  1. ↑ J. Krutmann: Environment-induced aging processes. In: Annual Report 2008 German Research Foundation
  2. ↑ P. Dammann: Senescence in African sand graves (Bathyergidae, Rodentia) with special consideration of the genus Fukomys. Dissertation, University of Duisburg-Essen, 2006
  3. ↑ TBL Kirkwood, MR Rose: Evolution and senescence - late survival sacrificed for reproduction. In: Philosophical Transactions of the Royal Society of London Series B , 332, 1991, pp. B15-B24. PMID 1677205 (Review)
  4. ↑ JR Speakman et al. a .: Living fast, dying when? The link between aging and energetics. In: J Nutr 132, 2002, pp. 1583S-1597S. PMID 12042467 (Review)
  5. ↑ TBL Kirkwood: Evolution of aging. In: Nature 270, 1977, pp. 301-304. PMID 593350
  6. ↑ C. Rott: Marketing strategies for older people. (PDF) WLSB popular sports conference, June 11, 2005
  7. ↑ J. Mitteldorf: Can experiments on caloric restriction be reconciled with the disposable soma theory for the evolution of senescence? In: Evolution 55, 2001, pp. 1902-1905. PMID 11681746
  8. ↑ EJ Masoro: Overview of caloric restriction and aging. In: Mech Aging Dev 126, 2005, pp. 913-922. PMID 15885745 (Review)
  9. ^ DP Shanley and TB Kirkwood: Calorie restriction and aging: a life-history analysis. In: Evolution 54, 2000, pp. 740-750. PMID 10937249