A review article published in Nature Reviews Genetics integrates evolutionary theory, comparative genomics, and large-scale human genetics to explain why aging occurs and why aging rates vary among individuals and species.
The authors, Dr. Melike Dönertaş of the Leibniz Institute on Aging – Fritz Lipmann Institute (FLI) in Jena and Professor Dame Linda Partridge of University College London and the Max Planck Institute for Biology of Ageing, describe that modern humans survive into old age, experiencing consequences of biological pathways optimized for youth and harmful mutations that natural selection does not efficiently eliminate because they act late in life.
Key Mechanisms
- Selection shadow: Natural selection is less effective with age, allowing harmful late-acting traits to accumulate.
- Trade-offs: Limited energy allocation between reproduction and maintenance can lead to faster aging.
- Mutation accumulation: Harmful genetic variants with late effects are weakly removed by selection.
- Antagonistic pleiotropy: Genes beneficial early in life can contribute to diseases in old age.
Modern Implications
The demographic transition—from high birth and death rates to low birth rates and high life expectancy—increases the relevance of these mechanisms. More people survive to old age, experiencing the consequences of selection shadow and youth-optimized pathways. Modern environments (abundant food, less physical activity, medical care) differ from ancestral conditions and unmask trade-offs.
Aging results from the interplay of genetic make-up, life history, environmental conditions, and population structure. Conserved biological processes known as "hallmarks of aging" include DNA instability, mitochondrial dysfunction, impaired nutrient metabolism, and accumulation of damaged proteins and aging cells. Signaling pathways like insulin/IGF-1 and mTOR regulate these processes and are conserved across species.
Statements from Authors
Dr. Melike Dönertaş stated: "An evolutionary view of aging isn't just a historical curiosity - it points to the conserved, ancient pathways whose continued activity in later life contributes to age-related disease, and where interventions are therefore most likely to work."
Professor Dame Linda Partridge stated: "Furthermore, it also reframes the goal: not simply extending lifespan, but partially relieving the late-life costs of a biology that natural selection optimized for early life - so that more of life is spent in good health."
The review proposes an integrative framework linking evolutionary theory, molecular biology of aging, and modern demographic and environmental conditions. Future research could investigate how demographic changes directly impact molecular and physiological aging processes.