One boat is red, one is green. The sails are a different shape. One has a cook, the other a raconteur. But they're both going to China, and both are going to take a long time in doing so. This little scene is what springs to mind when I see people debating the merits of different attempts to develop drugs that can slow aging. Slowing aging is the slow and expensive path to a poor end result:
It is likely to be easier and less costly to produce rejuvenation therapies than to produce a reliable and significant slowing of aging. A rejuvenation therapy doesn't require a whole new metabolism to be engineered, tested, and understood - it requires that we revert clearly identified changes to return to a metabolic model that we know works, as it's used by a few billion young people already. Those rejuvenation therapies will be far more effective than slowing aging in terms of additional years gained, since you can keep coming back to use them again and again. They will also help the aged, who are not helped at all by a therapy that merely slows aging.
We who are middle aged have a few decades of leeway - in which one development path or another will be pursued. If at the end of the day, when we are old and damaged, the result is a therapy that only slows aging, then we are out of luck. Thanks for playing.
But today, the vast majority of longevity research is focused on the slow boats to China - on producing ways to change human metabolism to modestly slow down age-related degeneration. This state of affairs will be the death of us all, unless the focus shifts to the Strategies for Engineered Negligible Senescence and other repair-based approaches to reversing the damage of aging.
In any case, here is a Technology Review article that looks at the slow boats: lines of research that won't make much of a meaningful and direct difference to the longevity of the presently middle aged, but which are illustrative of the mainstream of present aging and longevity research:
Elixir Pharmaceuticals, which was cofounded by Kenyon and Guarente in 1999 to translate their findings on the genetics of aging into a pill, was once "the leading commercial effort to turn research on aging into antiaging drugs," says Stipp. But the company has been far less successful than Sirtris in generating funding and excitement; today it employs just a handful of people, who are still pursuing sirtuins but have also moved on to developing other types of drugs. (Both Kenyon and Guarente have since left Elixir. Guarente joined Sirtris's scientific advisory board in 2007.) Peter S. DiStefano, chief scientific officer of Elixir, is no fan of the rival company, accusing it of weak science and overzealous claims. "While Sirtris was way more successful than Elixir from a business perspective, at least I have my scientific integrity and can look at myself and say I did the right thing the right way," he says.
But some scientists doubt that sirtuins hold the key to life extension; for one thing, sirtuin activation hasn't been shown to extend life in healthy animals. A number of other molecular mechanisms are also under close scrutiny for their effects on aging. Kenyon, director of the Hillblom Center for the Biology of Aging at UCSF, points to a different drug, called rapamycin; as Stipp explains, one way it appears to lengthen life is by slowing the production of the proteins needed for cell division. As more proteins are produced, so are more defective proteins, which can accumulate in cells and contribute to the symptoms we see as aging.
And so forth. Elixir, Sirtris, and others in the wings are just the early examples of a great wave of similar ventures that will arrive over the next decade, each based on some newly discovered and distinct aspect of metabolism that might be manipulated with drugs in order to modestly slow aging.
My prediction, as above, is that none of these efforts will ultimately affect your life expectancy in any meaningful way. We will either develop working repair strategies for age-related biological damage, such as by realizing SENS, and live for additional centuries in good health, or we will get to live a few years longer by using age-slowing drugs. The technology for either result is achievable within a few decades of now, assuming adequate funding. I know which path I prefer.