Reliability Theory Explains Human Aging and Longevity

PRESS RELEASE

Our bodies backup systems don't prevent aging, they make it more certain. This is one offshoot of a new "reliability theory of aging and longevity" by two researchers at the Center on Aging, NORC at the University of Chicago.

The authors presented their new theory at the National Institutes of Health (NIH) conference "The Dynamic and Energetic Bases of Health and Aging" (held in Bethesda, NIH). Their theory of aging has been published by the "Science" magazine department on aging research, Science's SAGE KE ("Science of Aging Knowledge Environment").

The authors say, "Reliability theory is a general theory about systems failure. It allows researchers to predict the age-related failure kinetics for a system of given architecture (reliability structure) and given reliability of its components."

"Reliability theory predicts that even those systems that are entirely composed of non-aging elements (with a constant failure rate) will nevertheless deteriorate (fail more often) with age, if these systems are REDUNDANT in irreplaceable elements. Aging, therefore, is a direct consequence of systems redundancy."

In their paper, "The quest for a general theory of aging and longevity" (Science's SAGE KE [Science of Aging Knowledge Environment] for 16 July 2003; Vol. 2003, No.28, 1-10. http://sageke.sciencemag.org ), Leonid Gavrilov and Natalia Gavrilova offer an explanation why people (and other biological species as well) deteriorate and die more often with age.

Interestingly, the relative differences in mortality rates across nations and gender decrease with age: Although people living in the U.S. have longer life spans on average than people living in countries with poor health and high mortality, those who achieve the oldest-old age in those countries die at rates roughly similar to the oldest-old in the U.S.

The authors explain that humans are built from the ground up, starting off with a few cells that differentiate and multiply to form the systems that keep us operating. But even at birth, the cells that make up our systems are full of faults that would kill primitive organisms lacking the redundancies that we have built in.

"It's as if we were born with our bodies already full of garbage," said Gavrilov. "Then, during our life span, we are assaulted by random destructive hits that accumulate further damage. Thus we age."

"At some point, one of those hits causes a critical system without a back-up redundancy to fail, and we die."

As the authors puts it, "Reliability theory also predicts the late-life mortality deceleration with subsequent leveling-off, as well as the late-life mortality plateaus, as inevitable consequences of REDUNDANCY EXHAUSTION at extreme old ages."

All those who have achieved the oldest-old age have very few redundancies remaining, therefore they can't accumulate many more defects: They simply die when the next random shock hits a critical system. Hence, the mortality rates tend to level off at extreme old ages, and people all over the world die at relatively similar rates on average. The initial differences in body reserves (redundancy) eventually disappear.

In the authors' words, "The theory explains why relative differences in mortality rates of compared populations (within a given species) vanish with age, and mortality convergence is observed due to the exhaustion of initial differences in redundancy levels."

This fundamental theory of aging and longevity is grounded in a predictive mathematical model that accounts for questions raised by previous models addressing the mechanisms of aging, mortality, survival and longevity.

The authors are research associates at the Center for Aging at the University of Chicago's National Opinion Research Center. Their research was sponsored by the National Institute on Aging. The authors are invited to present and discuss their theory at the forthcoming 10th Congress of the International Association of Biomedical Gerontology (England, September 2003), organized by Dr. Aubrey de Grey (http://www.gen.cam.ac.uk/iabg10/abs/Gavrilov2.htm)

Additional information on new theory is available at:

http://longevity-science.org/

and

http://longevity-science.org/SAGE-KE-03.pdf

Medline abstract of this new publication is attached below:

===============Entrez PubMed Results=================

Sci Aging Knowl Environ. 2003 Jul 16;2003(28):RE5. Related Articles, Books, LinkOut

The quest for a general theory of aging and longevity.

Gavrilov LA, Gavrilova NS.

Center on Aging, National Opinion Research Center/University of Chicago, Chicago, IL 60637, USA. lagavril@midway.uchicago.edu

Extensive studies of phenomena related to aging have produced many diverse findings, which require a general theoretical framework to be organized into a comprehensive body of knowledge. As demonstrated by the success of evolutionary theories of aging, quite general theoretical considerations can be very useful when applied to research on aging. In this theoretical study, we attempt to gain insight into aging by applying a general theory of systems failure known as reliability theory. Considerations of this theory lead to the following conclusions: (i) Redundancy is a concept of crucial importance for understanding aging, particularly the systemic nature of aging. Systems that are redundant in numbers of irreplaceable elements deteriorate (that is, age) over time, even if they are built of elements that do not themselves age. (ii) An apparent aging rate or expression of aging is higher for systems that have higher levels of redundancy. (iii) Redundancy exhaustion over the life course explains a number of observations about mortality, including mortality convergence at later life (when death rates are becoming relatively similar at advanced ages for different populations of the same species) as well as late-life mortality deceleration, leveling off, and mortality plateaus. (iv) Living organisms apparently contain a high load of initial damage from the early stages of development, and therefore their life span and aging patterns may be sensitive to early-life conditions that determine this initial damage load. Thus, the reliability theory provides a parsimonious explanation for many important aging-related phenomena and suggests a number of interesting testable predictions. We therefore suggest adding the reliability theory to the arsenal of methodological approaches applied to research on aging.

PMID: 12867663 [PubMed - in process]

weblink:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12867663&dopt=Abstract