Species Lifespan Predicted by Rate of Telomere Shortening
New research has indicated that a species’ lifespan can be predicted by the rate of telomere shortening but not by the initial telomere length, as previously thought.
Telomeres are repetitive sequences of DNA nucleotides found at the end of chromosomes. They protect the chromosome from degradation during cell division. As species age, the length of telomeres decline. At birth in humans have 11 kilobases (kba) of telomeres, but by old age only four kba remain. Many age-related diseases, including cancer, are related to telomere shortening.
Eight different species were investigated for the study including dolphins, elephants and flamingos. For each species animals of different ages were studied. As the animals were taken from the zoo, the age of each animal was known. Each animal had a blood sample taken and the length of their telomeres determined, meaning a telomere shortening rate could be calculated for each species.
No correlation was found between species lifespan and initial telomere length. The shortening rate of telomeres for each species shows strong correlation with species lifespan and is a much better predictor of lifespan that species size. For example, the maximum lifespan of a dolphin is 51.6 years while that of a mouse is 4 years. Dolphins’ telomeres shorten by 0.766 kba a year, whilst mouse telomeres shorten by 6.2 kba a year.
The scientists aim to now investigate species that have long lifespans for their size, such as the naked mole rat.
Understanding how telomere shortening rates vary across species could help scientists identify methods of preventing age related diseases or even slowing down the ageing process.