Media playback is unsupported on your device Media caption The scientists looked at how long 99 zebra finches lived

Scientists at Glasgow University say they have found a key genetic indicator of how long an individual will live.

They say the lengths of tiny pieces of DNA called telomeres indicate whether a young creature is likely to live long into old age.

But before you rush out to get your telomeres stretched - were such a process possible - it is worth pointing out that the creatures they have been working with are not humans but altogether shorter-lived zebra finches.

Everything that is made up of living cells contains chromosomes: the genetic code that makes us what we are.

At the ends of each chromosome lie the telomeres. They have been likened to the caps on the ends of shoelaces - they stop things from unravelling.

Over time they wear down - and when they do, the DNA they protect is compromised and the cell can malfunction or die.

This is where the zebra finches came in: how early and accurately could longer telomeres predict a longer life?

To find out, the Glasgow researchers collaborated with colleagues at Exeter University, with Glasgow's Prof Pat Monaghan leading the team.

Tiny blood samples were taken from a group of 99 zebra finches and the lengths of their telomeres measured. They were tested again throughout their lifetimes.

To find out how long the birds lived, the researchers had to wait until they died. The first turned up its claws in just over six months. But the last hardy specimen kept them waiting almost nine years.

In every case the longest lived birds had the longest telomeres, but the best predictor of lifespan was the length of the telomeres at just 25 days old.

Life conditions

Prof Monaghan says the study shows the importance of processes acting early in life.

The next step will be to find out why the length of telomeres can vary so much from individual to individual.

"We now need to know more about how early life conditions can influence the pattern of telomere loss and the relative importance of inherited and environmental factors," she said.

The results of the research have been published in the Proceedings of the National Academy of Sciences USA.

They are certain to raise the question of whether our telomeres are similar predictors of how long we will live.

But it is a big leap from the laboratory to the real world - whatever our telomeres may say, human lifespans also have to contend with additional factors like diet, drink and stress.

Wild finches, meanwhile, have snakes and birds of prey to worry about.

The bottom line for now? Ask not for whom the zebra finch chirps...