What protein in the blood, according to a March 2026 study, could serve as a universal marker for aging across species?

The protein in the blood that, according to a February 2026 study, could serve as a universal marker for aging across species is neurofilament light chain, often abbreviated as NfL. This protein is a crucial structural component of neurons, forming part of the internal scaffolding within their long extensions, called axons. When neurons are damaged, stressed, or simply undergo age-related changes, NfL is released from these nerve cells and can be detected in the bloodstream. Higher levels of NfL in the blood are therefore indicative of neuronal damage or degeneration.

Recent research published in PLOS Biology by Bergmann et al. in February 2026 highlighted NfL's potential as a cross-species biomarker. The study demonstrated that blood levels of NfL increase with age not only in humans but also in a wide array of other animals, including mice, cats, dogs, and horses. This consistent age-related increase across diverse species suggests that NfL could be a conserved indicator of biological aging and neurological health across the animal kingdom.

The implications of this discovery are significant. Identifying a universal aging marker like NfL could revolutionize our understanding of the aging process itself, offering a standardized way to assess biological age and potentially predict mortality across different species. This opens doors for new research into aging interventions, veterinary diagnostics, and even conservation biology, allowing for better monitoring of animal health and lifespan.