An article at The Scientist is illustrative of the focus of that portion of the gerontology mainstream presently supporting healthy life extension: work to change human metabolism so as to slow the rate of degeneration. "In the absence of planned form and designed function, what we have is a living machine that appears well thought out, but which fails when operated beyond its biological warranty period. ... Anyone who understands how time takes its toll on the body and mind, however, will recognize that designing a human body built to last requires far more substantive changes than meddling with simple anatomy. So we've asked our experts to fiddle with physiology and tinker with the inner mechanics of life at its most basic biologic level. Although it is inevitable, for now, that all systems in the body experience some level of functional decline with the passage of time, not all components of the body degrade at the same rate. Furthermore, some structures are more vulnerable than others." And herein lies the problem - reengineering metabolism is an inefficient and difficult path in comparison to working to repair the damage of aging.