The hallmarks of ageing, and why they matter

Ageing research groups the biology of getting older into a small number of recurring mechanisms: genomic instability, telomere attrition, epigenetic drift, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem-cell exhaustion and altered intercellular communication. Two points make this framework useful rather than decorative. First, each hallmark comes with measurable markers, so interventions can be evaluated instead of asserted. Second, the hallmarks interact — improving mitochondrial function changes senescent-cell signalling, and nutrient sensing sits upstream of proteostasis. For a research programme, the practical consequence is modest and useful: pick a pathway, pick a marker, and be explicit about whether the evidence for moving that marker comes from cell culture, from animal models, or from controlled human trials.