Researchers have claimed that biological age and life expectancy of a person can be predicted by measuring an individual's DNA.
Scientists at the University of East Anglia studied the length of chromosome caps - known as 'telomeres' - in a 320-strong wild population of Seychelles Warblers on a small isolated island.
"We saw that telomere length is a better indicator of life expectancy than chronological age - so by measuring telomere length we have a way of estimating the biological age of an individual - how much of its life it has used up," Lead researcher, Dr David S Richardson said.
The research shows that individuals differ radically in how quickly their telomeres shorten with age, and that having shorter telomeres at any age is associated with an increased risk of death.
Telomere length is a better indicator of future life-expectancy than actual age and may, therefore, be an indicator of biological age.
The 20-year research project is the first of its kind to measure telomeres across the entire lifespan of individuals in a wild population.
Telomeres are found at the end of chromosomes. They act as protective caps to stop genes close to the end of the chromosome degenerating Ņ like the hard plastic ends of a boot lace.
"Over time these telomeres get broken down and become shorter. When they reach a critical short length they cause the cells they are in to stop functioning," Richardson said.
"This mechanism has evolved to prevent cells replicating out of control Ņ becoming cancerous. However the flip side is that as these zombie cells build up in our organs it leads to their degeneration - ageing - and consequently to health issues and eventually death. Telomeres help safeguard us from cancer but result in our ageing," he said in a statement.
Researchers studied the warbler population on Cousin Island. Blood samples were collected twice a year and telomere length analysed.
"We wanted to understand what happens over an entire lifetime, so the Seychelles Warbler is an ideal research subject. They are naturally confined to an isolated tropical island, without any predators, so we can follow individuals throughout their lives, right through to old age," said Richardson.