A 2026 study investigated aging through the use of transcriptomics:

“By constructing transcriptomic clocks of expected mortality across >11,000 samples from mouse, rat, macaque and human, we provide a unified framework that integrates age-associated transcriptional change with the direction and magnitude of lifespan modulation by interventions, enabling a quantitative and biologically interpretable readout of health status.

While chronological clocks captured many detrimental conditions (e.g., chronic diseases or certain short-lived genetic models), they were comparatively less responsive to lifespan-extending interventions, consistent with reports that longevity treatments often only modestly reverse age-associated transcriptomic signatures. In contrast, mortality clocks robustly distinguished both short- and long-lived models and showed strong associations with human time-to-death, approaching the predictive performance of second-generation DNAm mortality clocks while remaining biologically interpretable.

Our results support and extend DNAm-based observations that heterochronic parabiosis in old animals and early embryogenesis can induce molecular age deceleration. In old heterochronic parabionts, mortality clocks detected a sustained tAge reduction that persisted for 2 months after detachment from young partners. Together, these findings support the view that early development contains a conserved rejuvenation-like phase, and that systemic environment can partially reset molecular age later in life.

https://www.nature.com/articles/s41586-026-10542-3 “Universal transcriptomic hallmarks of mammalian ageing and mortality”

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Applying this study to An environmental signaling paradigm of aging theory and its derivative studies through Reversing biological age in rats and https://link.springer.com/article/10.1007/s11357-023-00980-6 “Reversal of biological age in multiple rat organs by young porcine plasma fraction” could clarify involved mechanisms. This research area doesn’t have current sponsors, though, to carry out rat lifespan studies.

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