Which mechanism or intervention will be validated as the primary key to stopping or reversing human ageing?

rationale:

The resolution criteria set an exceptionally high bar: overwhelming scientific consensus, decisive clinical evidence of a 'root cause,' and a dramatic 50+ year healthy lifespan extension. Because no current intervention is remotely close to this threshold, these estimates effectively reflect a prior over which underlying theory of aging will ultimately prevail. Two dominant paradigms account for over 60% of the probability: a multifactorial systems approach and epigenetic reprogramming.

A Combination Systems Approach (31%) The prevailing academic consensus relies on the 'Hallmarks of Aging' framework (expanding from 9 to 12+ hallmarks), which models aging as a deeply interconnected, multifactorial process. Prominent scientific reviews consistently assert there is 'no silver bullet' for aging. If human aging is irreducibly complex, achieving a dramatic 50+ year lifespan extension will require simultaneously targeting multiple interacting damage and regulatory pathways. Because this directly reflects current broad consensus, it holds the highest probability of being validated as the necessary paradigm.

Epigenetic Reprogramming / Partial Reprogramming (30%) While the systems approach leads on current consensus, epigenetic reprogramming (e.g., partial reprogramming via Yamanaka OSK factors) is the strongest candidate for a single, upstream mechanism capable of true rejuvenation rather than mere slowing. Reprogramming uniquely satisfies the 'stopping or reversing' framing by resetting the cellular clock and concurrently ameliorating multiple downstream hallmarks, including genomic instability, telomere attrition, and mitochondrial dysfunction [S1568163726000012; PMC12340157]. This mechanism is supported by the Information Theory of Aging, which posits epigenetic information loss as the reversible root cause [Yang-Sinclair Cell 2024; HMS]. It also boasts unprecedented capital momentum (e.g., Altos Labs' ~$3B funding, Retro Bio) and is crossing the clinical threshold, with the first FDA-cleared human trial for partial reprogramming (Life Biosciences ER-100/OSK) dosing patients in mid-2026 [lifespan.io; businessinsider].

mTOR / Nutrient Sensing (10%) and Senescent Cell Clearance (8%) These mid-tier candidates possess the most robust existing clinical and experimental foundations but are hindered by the magnitude of the required 50+ year lifespan extension. mTOR inhibition (rapamycin) is the most reliable mammalian lifespan extender to date (e.g., 15-20% extension in the NIA ITP [PMC12226543; aging-us]), with early human healthspan signals (PEARL 2025). However, mTOR primarily modulates and slows aging rather than reversing it, suggesting a biological ceiling that falls short of the resolution criteria. Senolytics similarly clear accumulated damage but do not rewrite the underlying upstream aging clock.

Downstream Single Hallmarks (3-4% each) Mechanisms such as telomere shortening, NAD+ decline, mitochondrial dysfunction, DNA damage, proteostasis failure, and systemic inflammation (inflammaging) are increasingly viewed as downstream consequences or partial interacting components rather than singular master drivers. Furthermore, aggressively upregulating some of these specific pathways (e.g., telomerase activation, NAD+) carries theoretical or observed cancer-risk caps, significantly limiting their plausibility as a standalone primary key for dramatic, safe lifespan extension.