In short
The hallmarks of aging are a framework of interconnected biological mechanisms — originally nine, expanded to twelve — proposed as the shared drivers underlying aging across tissues and species.
The framework was introduced in a widely cited 2013 paper in the journal Cell by López-Otín, Blasco, Partridge, Serrano, and Kroemer, titled "The Hallmarks of Aging." The original nine hallmarks were: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication.
In a 2023 follow-up paper, the same group (with additional co-authors) expanded the list to twelve hallmarks, adding disabled macroautophagy, chronic inflammation (inflammaging), and dysbiosis (gut microbiome imbalance). The framework groups hallmarks into primary causes of damage, antagonistic responses to that damage, and integrative hallmarks that produce the overall functional decline.
The value of the framework is organizational, not itself a claim of proof: it gives researchers and, by extension, this glossary a shared vocabulary for mechanisms that are each independently studied to different degrees. Some hallmarks (like genomic instability and telomere attrition) have decades of supporting mechanistic and epidemiological data; others (like altered intercellular communication) are more provisional categories under active refinement. Treat the hallmarks framework as an organizing lens for aging biology, not as twelve independently validated drug targets with equal evidence behind each.
Worth remembering
- Introduced in a 2013 Cell paper by López-Otín et al.; expanded to twelve hallmarks in 2023.
- Groups mechanisms into primary damage, antagonistic responses, and integrative hallmarks.
- An organizing framework, not twelve equally proven drug targets.