Your passport says 47. Your cells might disagree — and now there's a way to find out

Two ages, one body

Everyone has a chronological age — the number of years since birth. Fewer people know they also have a biological age: a measure of how much cellular aging has actually occurred, which can diverge significantly from the calendar date. Two people born in the same year can have biological ages that differ by a decade or more, depending on genetics, lifestyle, environmental exposures, and the effectiveness of their cellular maintenance processes. Biological age predicts healthspan and longevity outcomes more accurately than chronological age — which is why its measurement has become a focus of serious longevity research.

Epigenetics: how aging writes itself into your DNA

The technology behind biological age testing is epigenetics — specifically, the measurement of DNA methylation patterns. As cells age, characteristic changes occur in which methyl groups are attached to specific cytosine bases in the genome. These methylation patterns shift in predictable ways across thousands of genomic sites, and collectively they function as a molecular clock. The most validated version, the Horvath Clock (developed by Steve Horvath at UCLA), can predict biological age from a saliva sample with an accuracy of roughly 3.6 years, and its predictions correlate with health outcomes in large population studies.

What an at-home test actually measures

Aeternum's DNA Biological Age Test analyses methylation patterns across hundreds of thousands of genomic sites from a simple at-home saliva sample. The sample is processed in a CLIA-certified laboratory (the same accreditation standard used for clinical diagnostic labs), and the result is a biological age score with an accompanying report that explains the findings and highlights evidence-based areas for intervention. The test provides a baseline — and can be repeated over time to track whether lifestyle or supplementation strategies are measurably reversing biological aging markers.

What to do with the number

A biological age that's older than your chronological age isn't a verdict — it's data. The methylation patterns that generate the score are at least partially modifiable: exercise, caloric restriction, sleep quality, stress management, and certain supplements (including several that work through the NAD+ and mitophagy pathways) have all shown measurable effects on epigenetic age markers in research settings. Knowing your biological age gives the interventions a baseline to measure against — without it, you're optimising without feedback.

The shift from reactive to preventive

Most engagement with medical testing is reactive: you measure because something is wrong. Biological age testing represents a different philosophy — understanding your cellular trajectory before symptoms appear, so you can course-correct while the interventions are still working. For anyone approaching longevity as a proactive rather than reactive endeavour, a baseline biological age is arguably the most meaningful first data point available.