Epigenetic Signatures of Ageing in Asian Elephants Revealed by Reduced Representation Bisulphite Sequencing

= 0.96, MAE = 4.82 years), corresponding to a relative error of 6.06%, comparable to epigenetic clocks developed for humans and other non-model species. Longitudinal analyses revealed heterogeneous epigenetic ageing trajectories, with most individuals showing increases in epigenetic age over time, while others exhibited relatively slower or minimal change, indicating a potential inter-individual variation in ageing processes. Functional enrichment analyses revealed that age-associated CpGs were enriched in genes and pathways related to development, neurogenesis, metabolism and social or physiological regulation, including oxytocin, apelin and melanogenesis signalling. Age-related methylation changes were characterised by predominant hypermethylation in CpG islands and genic regions, consistent with patterns reported across mammals. Together, these findings demonstrate that epigenetic clocks capture biologically meaningful features of ageing that could be linked to life-history traits. As long-lived mammals with complex social systems and extended reproductive capacity, Asian elephants provide a valuable comparative model for investigating the molecular architecture of ageing. This study contributes to the growing field of comparative epigenetic ageing and highlights the potential of DNA methylation-based approaches to inform evolutionary and conservation-relevant research when applied in appropriate ecological and methodological contexts.