Epigenetic clocks and nonlinear aging in Odocoileus deer

A mule deer (Odocoileus hemionus) epigenetic clock estimates chronological age with accuracy comparable to mammalian clocks (r ≈ 0.9; MAE ≈ 5% of species lifespan).

• Why it matters: Wildlife demography depends on age structure, but epigenetic clocks are available for only two cervid species, limiting age estimation in intensively managed ungulates.
• What they did: The study developed a mule deer clock and a multi-species Odocoileus clock, then used cross-sectional and longitudinal epigenetic age estimates to test nonlinear methylation dynamics.
• The result: Cross-sectional estimates supported nonlinear age-associated methylation across the mule deer lifespan, while longitudinal changes suggested cross-sectional-optimized clocks may lack resolution for short-term within-individual shifts.