Aging clocks for men and women differ sharply

Researchers drew on a large-scale human aging phenome: a collection of thousands of measurements of bodily functions and substances, tracked over time. Using this data, the researchers built separate clocks for men and women. The study was published in Nature Aging. The principle behind such clocks is that biological age (how old your body functions) can diverge from your calendar age.

Metabolism and tumour markers as aging signals

The aging clocks identified systemic metabolic signals and circulating tumour markers (substances in the blood that can rise with cancer) as notable features of biological aging. This does not mean that everyone with elevated markers has cancer; rather, their levels appear to partly determine how quickly someone ages biologically.

The study also mapped aging transitions: points at which the pace or pattern of aging clearly differs between men and women. These are not sharp inflection points, but gradual shifts that unfold differently by sex. The researchers stress that this distinction matters for how aging interventions are designed and tested.

Why sex differences in aging matter

Much existing aging research combines men and women in a single model, obscuring sex-specific patterns. Building separate clocks makes visible patterns that would otherwise remain hidden. Women live longer on average than men, but spend a greater share of those extra years with chronic conditions. That paradoxical pattern, the researchers suggest, may partly be explained by the differences these clocks reveal.

The study is observational in nature. The clocks describe aging patterns, but do not yet prescribe which interventions are most effective for men or women separately. That is a next step.

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