The canonical evidence-tier scale

Evidence across the network is shown on a visible seven-tier scale (1 = healthy-aging human lifespan RCT, down to 7 = in vitro / mechanism) and is never collapsed into a single marketing score. Tier 1 is empty network-wide by design: no mechanism has a healthy-aging lifespan RCT. Note the deliberate distinction between tier 2 (a human clinical-outcome RCT in a disease population) and a healthy-aging lifespan result — the former is real and important, but it is disease treatment, not an anti-aging effect. This is the canonical version of the scale; each mechanism site links back to it rather than restating it.

TierLabelWhat it means
1Healthy-aging human lifespan RCTRandomized, hard lifespan / healthy-aging endpoint in a healthy-aging population. EMPTY everywhere in this network -- no mechanism site has one.
2Human clinical-outcome RCT -- disease populationRandomized, hard clinical outcome but in a DISEASE population, not healthy aging (e.g. danazol in telomeropathy; CoQ10 in heart failure; imetelstat in MDS). Real and important, but it is disease treatment, not evidence of an anti-aging effect.
3Human RCT -- biomarker endpointRandomized, but the endpoint is a biomarker (telomere length, senescent-cell burden, a functional marker), not a clinical outcome or lifespan. A biomarker change is not a clinical outcome.
4Human pilot / observational -- biomarkerSmall pilot or observational cohort with a biomarker endpoint; no randomized healthy-aging intervention.
5Animal lifespan studyLifespan change in an animal model. Informative for biology, not a human outcome.
6Animal healthspan / disease-model / mechanismHealthspan, function, or disease-model change in an animal; no whole-organism lifespan endpoint.
7In vitro / mechanismCell-culture or biochemical mechanism; no whole-organism outcome.

The honesty-flag legend

Each site card carries one of three flags derived from the strength of its human evidence: ● green is reserved for a genuine healthy-aging human lifespan RCT and is empty across the whole network; ▲ amber marks real human data that is biomarker, pilot, observational, or disease-outcome grade — i.e. not a healthy-aging lifespan RCT (every live site is amber); ○ grey marks animal / mechanism-only data or, for planned sites, no published content yet. See how to read the evidence for the plain-language version.

How the hub sources

The hub is a navigational layer: it cites sites, not primary trials. Primary-source verification (Crossref / ClinicalTrials.gov confirmation of every identifier and datapoint) is done on each mechanism site, where the detailed evidence lives. The one primary source the hub verifies itself is the hallmarks reference, confirmed against the Crossref record — see the hallmarks page. Nothing on the hub overstates or re-grades what a site reports; the site’s honest one-liner is surfaced verbatim.