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RE: Peter Parsons in Biogerontology
Jim,
I guess this goes back to the old joke about the need to pick your parents
to get the best genes.
I notice they do not identify radiation has a useful stressor to increase
lifespan.
-- John
John Jacobus, MS
Certified Health Physicist
3050 Traymore Lane
Bowie, MD 20715-2024
E-mail: jenday1@email.msn.com (H)
-----Original Message-----
From: Muckerheide [mailto:muckerheide@attbi.com]
Sent: Tuesday, October 01, 2002 7:27 AM
To: radsafe@list.vanderbilt.edu
Subject: Peter Parsons in Biogerontology
Friends,
Our friend Peter Parsons has published the following paper.
Regards, Jim Muckerheide
Radiation, Science, and Health
===============================
Biogerontology 2002;3(4):233-41
Life span: does the limit to survival depend upon metabolic efficiency
under stress?
Parsons PA.
La Trobe University, Bundoora, Vic. 3083, Australia; Author for
correspondence: P.O. Box 906, Unley, SA 5061, Australia (e-mail:
pparsons@senet.com.au; fax: +61-8-8373-5557)
Survival to old age in natural populations is enhanced by high vitality
and resilience which depends upon substantial homeostasis and energetic
and metabolic efficiency underlain by genes for stress resistance. Under
this assumption increased longevity follows from primary selection for
stress resistance where stress targets energy carriers. Furthermore old
and young fitness should be correlated irrespective of age under the
stressful selection regime of natural populations. In contrast,
antagonistic pleiotropy is most likely under the less rigorous selection
regime of well-nourished humans and laboratory populations surviving to
old age. Similarly, hormesis for longevity, for example from a mild
temperature stress or restricted food intake is most likely under benign
environmental conditions. Assuming that aging in natural populations
depends upon ecological circumstances, large evolutionary increases in
life span are unlikely under the stress theory of aging since organisms
are frequently close to their limits of survival where metabolic
efficiency is at a premium. Exceptions can occur in island populations
and for mutants under laboratory conditions since the risks from
environmental hazards are reduced, and life span becomes extended as a
consequence. In modern human populations, selection for stress
resistance is less intense than in earlier times which should be
permissive of the accumulation of stress-sensitive mutants under the
mutation-accumulation theory of aging. However, this process is
ultimately likely to restrict the evolution of life-span extensions in
the future especially if abiotic conditions deteriorate, when survival
would depend more directly on metabolic efficiency under stress.
http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list
_uids=12232505&dopt=Abstract
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