I've been kind of hoping that someone would come up with a magic pill to reverse aging some time in the next forty or fifty years. I figured that around the time I've gone completely gray, I'll cash in my 401(k) use the resulting billion dollar cheque (not adjusted for inflation) to buy one of these pills. Alas, via Other magazine I learn that biologist Robin Holliday's paper “Aging is No Longer an Unsolved Problem in Biology,” makes clear that it ain't gonna happen.
For much of the 20th century, the accumulation of a considerable amount of information about the processes of aging did not reveal the underlying mechanisms. Toward the end of that century, the biological basis for aging became very much clearer. .... There is now much evidence that long-lived mammals have much more efficient maintenance mechanisms than short-lived mammals. Thus, aging can be defined as the eventual failure of maintenance. It also became apparent that many different maintenance mechanisms exist, and that these depend on very many genes and a considerable investment in metabolic resources .... aging is multicausal. It is also evident that the evolved design of many components of complex animals is incompatible with indefinite survival. We can therefore conclude that this evolved design is intrinsically related to the fact of aging. This in turn means that aging cannot be reversed ....This does suggest that we could genetically engineer future humans who don't age, though. They'd be as hungry as teenagers, I guess.