It was with some pleasure that I noticed the phrases "primary aging" and "secondary aging" have lately worked their way into the wider science press. I think this demonstrates that the public conversation about anti-aging, longevity research and strategies such as calorie restriction has advanced to the point at which more precise and careful language is needed - which means more people are talking, thinking about the topic, and asking sensible, intelligent questions.
Primary aging is the gradual - and presently inevitable - process of bodily deterioration that takes place throughout life: the accumulation of biochemical damage that leads to slowed movements, fading vision, impaired hearing, reduced ability to adapt to stress, decreased resistance to infections, and so forth. Secondary aging processes result from disease and poor health practices (e.g. no exercise, smoking, excess fat and other forms of self-damage) and are often preventable, whether through lifestyle choice or modern medicine. The two categories are somewhat fuzzy at the borders by these definitions; we hope that advancing medical and biotechnology will move the known and understood aspects of primary aging into the secondary aging category as rapidly as possible.
A paper from back in 2000 - an eternity ago in biotechnology development - still provides a good indication as to the present day position within mainstream generontology:
Nothing has been demonstrated to slow or reverse the primary aging process in humans; instead, the factors that are known to affect longevity do so by their influence on disease development, which is part of secondary aging. Preventive strategies against secondary aging are aimed at maintaining health and functional capacity and rectangularizing, rather than extending, the survival curve.
The main development in recent years is the growing acceptance amongst the mainstream that primary aging can be tackled, effectively and soon, and the start of a cultural transformation that will see longevity research no longer the instant death third rail of grantsmanship.
If you look at my Longevity Meme piece on anti-aging science and medicine, you'll see that a confusion - deliberate or otherwise - between primary and secondary aging is at the root of much of the conflict between business and science (and between reputable businesses and shysters). One can hope that the reputable end of the anti-aging marketplace takes the opportunity offered by a more sophisticated cultural conversation on longevity and aging to more accurately position their products ... but I'm not holding my breath there.