Researchers have found a correlation between the average lifespan of a species and the rate at which its telomeres are shortened.
Telomeres are structures at the ends of chromosomes that function to protect genes. However, every time a cell divides, telomeres become a little shorter. When telomeres reach a critical length, the cell stops dividing altogether in order to protect chromosomes from unravelling. Although it has been known for quite some time that telomeres play a role in ageing, no relationship had been found between telomere length and lifespan of each species. There are species with very long telomeres that are short-lived and vice versa.
“We have found a universal pattern, a phenomenon of biology that explains the life span of the species, and that warrants more research,” says María Blasco, head of the research group at the Spanish National Cancer Research Centre.
This study showed that it is not the initial length of telomeres, but their rate of shortening that correlates with species longevity. Telomere length was measured from individuals of 9 different species of birds and mammals at different ages, and telomere shortening rate per year was calculated. Interestingly, when considering the timepoint of the average lifespan, the length of telomeres at death appears to be about 75% of the original length.
The relationship between the average lifespan of each species and telomere shortening rate can be fitted to a power law curve, which is also commonly used to describe other natural phenomena such as population growth, body mass, and species extinction. The equation from this curve can further be used to accurately predict lifespan, at least with the current dataset in this study.
Moving forward, it would be worth conducting a longitudinal study, following animals and/or humans over their lifetime to confirm the findings of this study. In any case, "these results support the notion that critical telomere shortening and the consequent onset of telomeric DNA damage and cellular senescence are a general determinant of species life span.," the authors write in PNAS.