Thursday, February 01, 2007

Longevity: Part I

Cell homeostasis, tissue homeostasis, and organ homeostasis determine organismic homeostasis (Adam and Eve Don't Want to Get Old: New Strategies for Fighting Aging. Annals of the New York Academy of Science, Annals Extra. 8-29-2006). Therefore the efficiency of cells, tissues and organs in maintaining homeostasis would likely influence the longevity of the emergent organism.

To quantify the homeostasis efficiency of a complex system even low in hierarchy, like a eukaryotic cell, one might try valuating the degree/promptness of homeostasis of its major subsystems in response to a perturbation spectrum. But that could only quantify efficiency under the environmental conditions of the studies. Each condition might affect efficiency differently, and variably differently, in the various subsystems. Because an enormous number of environmental conditions test homeostasis-maintaining ability of the organism during a lifespan, one would need to obtain and integrate too much detail of human subsystems’ properties for any valuation of efficiency of homeostasis to have practical value in controlling human lifespan.

The property of the human system, viz., lifespan, emerges only when organismic homeostasis fails completely and death results. A model that could predict lifespan long in advance of death, even one that age-modified the prediction, might lend itself to teaching how to treat the system to improve the efficiency of homeostasis of its subsystems.

What form would such a model take? For personal benefit—a major product of aging research—the model would seem to require itself to interrogate the individual human system before running its lifespan-predicting algorithm. And do so each time as time goes by. One would want the model’s systems readout, however implemented and interpreted in relation to previous readouts, followed by a prediction of lifespan as well as a prescription of steps to take to reverse damage and improve homeostasis-maintaining ability. A massive-load-capable information-gathering-and-processing method, abstract, computational: a cyber-smart doctor, distributed geographically or miniaturized.

But that ideal model allows control of lifespan for extreme longevity, as opposed to merely extending it substantially beyond present norms. Yet, learning to extend lifespan substantially may crucially underpin any model that permits control of lifespan for extreme longevity. Minimized energy consumption as food extends lifespan in diverse genera. That would seem to have potential for obese humans, but not necessarily for non-obese humans. We do not know whether calorie minimization, ceteris paribus, extends lifespans in non-obese humans. If so, we might want to revise our quantitative criteria for obesity to retain its connotation of poor health. We have no firm idea what body mass indexes, or percent body fat, however adjusted for other anthropomorphic variables, associate with human lifespans substantially greater than current norms.

Depending on how extreme the possible longevity, achieving it may require the complex task of controlling the entire human environment, the biosphere at minimum. Hopefully, but likely, all humans will require a large core-biosphere-set of common conditions, however geo-regional, for super-efficient organismic homeostasis. In recognizing that, the motivation of individuals for youthful longevity may impel them to interact in ways to achieve that common set of conditions. Sacrifices might involve opposing nature’s algorithmic drive to reproduce. Doing that would step us closer to the question of optimal sustainable population size, and how to achieve that ethically.

The property of lifespan has interest because the desirer of longevity wants a long healthy mental life, a long-lived kingdom of the mind. Why? Because as one’s knowledge increases so do the number of paths for curiosity to pursue—and a healthy youthful mind dictates the exercise of curiosity. Because often one has ambitions and goals that require many prolonged stages. Because those who do believe in ‘afterlife’ feel they should get the greatest possible satisfaction from living before dying. Because living longer increases the chances of participating in breakthroughs to extreme longevity.

Though some suggest the possibility that someday supercomputers, perhaps quantum computers, will have the ability to simulate the processes that generate conscious and self-conscious experience in simulated humans living in a simulated biosphere (Tipler FJ. (1994) The Physics of Immortality: Modern Cosmology, God and the Resurrection of the Dead. New York: Doubleday). For all I know, I live as a simulation in a simulated world, as an experiment, perhaps an iterative run of a model program developed by model-building systems scientists beyond my ken.

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