Reacción a "Universal molecular ‘clocks’ of ageing and mortality identified in mammals"

The study can be considered high quality owing to its scale (more than 11,000 transcriptomes), its comparative multi-species design (mouse, rat, macaque and human), and its extensive validation across both in vivo and in vitro models as well as longitudinal human data. In addition, it integrates multiple tissues and employs different methodological approaches — including statistical models, machine learning and network analysis — which strengthens the robustness of the findings.

Nevertheless, there are important limitations. The study is correlational in nature, and its observational design prevents the establishment of causality; the transcriptomic changes observed could be consequences rather than drivers of ageing. Potential technical biases between heterogeneous datasets also remain, and although human data are included, much of the mechanistic evidence derives from animal models.

In terms of prior evidence, the work is consistent with existing ‘epigenetic clocks’, but it provides greater functional interpretability by directly linking genes and biological pathways to ageing, mortality and responses to interventions.

The implications of identifying universal transcriptomic signatures are profound. They suggest that ageing and mortality share a conserved molecular architecture across mammals, dominated by processes such as inflammation, cellular senescence and mitochondrial dysfunction, reinforcing the idea of common underlying ageing mechanisms. Inflammation is already known to be a marker of many diseases, including obesity and cancer. It is therefore not particularly surprising that it also emerges as a marker of ageing, probably as a response to the DNA damage that accumulates as cells grow older.

However, clinical translation remains limited. Although the transcriptomic clocks predict mortality in humans with accuracy comparable to epigenetic clocks, their practical application will require standardisation, cost reduction and prospective validation in clinical populations.

Overall, the study represents an important conceptual advance, but its clinical impact remains uncertain and will depend on demonstrating predictive utility and the capacity to guide interventions in real-world settings.