  Aging is analyzed as the spontaneous loss of adaptivity and increase in
fragility that characterizes dynamic systems. Cybernetics defines the general
regulatory mechanisms that a system can use to prevent or repair the damage
produced by disturbances. According to the law of requisite variety,
disturbances can be held in check by maximizing buffering capacity, range of
compensatory actions, and knowledge about which action to apply to which
disturbance. This suggests a general strategy for rejuvenating the organism by
increasing its capabilities of adaptation. Buffering can be optimized by
providing sufficient rest together with plenty of nutrients: amino acids,
antioxidants, methyl donors, vitamins, minerals, etc. Knowledge and the range
of action can be extended by subjecting the organism to an as large as possible
variety of challenges. These challenges are ideally brief so as not to deplete
resources and produce irreversible damage. However, they should be sufficiently
intense and unpredictable to induce an overshoot in the mobilization of
resources for damage repair, and to stimulate the organism to build stronger
capabilities for tackling future challenges. This allows them to override the
trade-offs and limitations that evolution has built into the organism's repair
processes in order to conserve potentially scarce resources. Such acute,
"hormetic" stressors strengthen the organism in part via the "order from noise"
mechanism that destroys dysfunctional structures by subjecting them to strong,
random variations. They include heat and cold, physical exertion, exposure,
stretching, vibration, fasting, food toxins, micro-organisms, environmental
enrichment and psychological challenges.
