An interesting discussion is presently ongoing over at the Gerontology Research Group email list, covering such topics as workable definitions for aging and the need for biomarkers of aging. I've touched on the topic of biomarkers for aging previously; it's an important issue for the research community. How can you rapidly determine that you have successfully developed an anti-aging technology that works in humans if you cannot tell how advanced the aging process is in any given individual, or if you cannot even agree on a working scientific definition for aging? Obviously you can wait around to count years and deaths, but that reliable fallback is not a good approach for those of us who would like to see working healthy life extension medicine in our lifetimes.
A good excerpt from the GRG conversation has made it's way to the transhumantech group, and is worth reading if you have an interest in the nuts and bolts of the field.
I should mention that, in my view, the Strategies for Engineering Negligible Senescence approach sidesteps many of the requirements for definitions and biomarkers. If researchers jump right on in and work on fixing what we know to be root causes of degeneration, then they can't be going far wrong. You don't need a unified theory of automotive decay to use a toolkit and spare parts to extend the lifespan of your car - the only difference between the human body and a car is the degree of complexity involved. When it comes to repairing the causes of degeneration in people, scientists can measuring the effectiveness of repair strategies on specific modes of age-related damage (mitochondrial mutations, extracellular junk, damaged DNA, etc) in isolation; improvements in repair capabilities in any one area should lead to incremental benefits to patients even while other modes of age-related damage are still taking place unabated. Provided that medical research can reliably identify all causes of age-related degeneration as science moves forward and time advances, researchers should be well set to solve the problem of aging incrementally - without the need for a comprehensive understanding at the outset.
As always, the crucial missing ingredients are significant funds and public support for this sensible, necessary, practical direction in aging research. This is a problem that folks like you and I can help to solve, however, by stepping up to support efforts like the Mprize for longevity research.