Biology of ageing: principles, challenges and perspectives.

Living systems owe their survival and health to a series of complex biochemical pathways of maintenance and repair. These defense systems create the homeodynamic space of an individual, which is characterized by stress tolerance, molecular damage control and continuous remodeling. Ageing, age-related diseases and eventual death are the consequences of a progressive shrinkage of the homeodynamic space, due to the failure of maintenance and repair. Whereas longevity assurance genes do affect the essential lifespan of a species, there are no ageing-specific gerontogenes to cause ageing and to limit the lifespan of an individual. The challenge of preventing, managing or treating age-related chronic diseases and other health problems requires abandoning the traditional "one-target, one-shot" biomedical approach. Wholistic methods incorporating lifestyle-based hormetic interventions, including food, physical activity and mental engagement, appear to be potentially more successful in maintaining health and in extending healthspan and longevity.