The Hallmarks of Aging paper was published earlier this year. It is an outline by a group of noted researchers that divides up degenerative aging into what they believe are its fundamental causes, with extensive references to support their conclusions, and proposes research strategies aimed at building the means to address each of these causes. This is exactly what we want to see more of in the aging research community: deliberate, useful plans that follow the Strategies for Engineered Negligible Senescence (SENS) model of approaching aging.
Read through the Hallmarks of Aging and you'll see that it is essentially a more mild-mannered and conservative restatement of the SENS approach to aging - written after more than ten years of advocacy and publication and persuasion within the scientific community by SENS supporters. To my eyes, the appearance of such things shows that SENS is winning the battle of ideas within the scientific community, and it is only a matter of time before it and similar repair-based efforts aimed at human rejuvenation dominate the field. Rightly so, too, and it can't happen soon enough for my liking. SENS and SENS-like research is the only way we're likely to see meaningful life extension technologies emerge before those of us in middle age now die, so the more of it taking place the better.
Aubrey de Grey, author of the original SENS proposals and now Chief Science Officer of the SENS Research Foundation that funds and guides rejuvenation research programs, is justifiably pleased by the existence of the Hallmarks of Aging. See this editorial in the latest Rejuvenation Research, for example:
On June 6th, a review appeared concerning the state of aging research and the promising ways forward for the field. So far, so good. But this was not any old review. Here's why: (a) it appeared in Cell, one of the most influential journals in biology; (b) it is huge by Cell's standards - 24 pages, with well over 300 references; (c) all its five authors are exceptionally powerful opinion-formers - senior, hugely accomplished and respected scientists; (d) above all, it presents a dissection of aging into distinct (though inter-connected) processes and recommends a correspondingly multi-pronged ("divide and conquer") approach to intervention.
It will not escape those familiar with SENS that this last feature is not precisely original, and it may arouse some consternation that no reference is made in the paper to that prior work. But do I care? Well, maybe a little - but really, hardly at all. SENS is not about me, nor even about SENS as currently formulated (though a depressing number of commentators in the field persist in presuming that it is). Rather, it is about challenging a profound, entrenched, and insidious dogma that has consumed biogerontology for the past 20 years, and which this new review finally - finally! - challenges (albeit somewhat diplomatically) with far more authority than I could ever muster.
Aging has been shown, over several decades, to consist of a multiplicity of loosely linked processes, implying that robust postponement of age-related ill-health requires a divide-and-conquer approach consisting of a panel of interventions. Because such an approach is really difficult to implement, gerontologists initially adopted a position of such extreme pessimism that all talk of intervention became unfashionable. The discovery of genetic and pharmacological ways to mimic [calorie restriction], after a brief period of confused disbelief, was so seductive as a way to raise the field's profile that it was uncritically embraced as the fulcrum of translational gerontology for 20 years, but finally that particular emperor has been decisively shown to have no biomedically relevant clothes.
The publication of so authoritative a commentary adopting the "paleogerontological" position, that aging is indeed chaotic and complex and intervention will indeed require a panel of therapies, but now combined with evidence-based optimism as to the prospects for implementing such a panel, is a key step in the elevation of translational gerontology to a truly mature field.
In essence, as de Grey points out, work on aging has been following the wrong, slow, expensive, low-yield path for a couple of decades: the path of deciphering the mechanisms of calorie restriction and altering genes and metabolism to slightly slow down aging. This path cannot result in large gains in life expectancy and long-term health, and it cannot result in therapies that will greatly help people who are already old. What use is slowing down the accumulation of the damage of aging if you are already just a little more damage removed from death, and frail and suffering because of it, and the treatment will meaningfully alter none of that? If we want to add decades or more to our healthy life spans before we die, then rejuvenation and repair of damage are what is needed: ways to reverse frailty, remove suffering, and restore youthful function.