A healthy lifestyle may increase the lifespan of our great grandchildren, scientists say.
It is already known that the environment, including what we eat and the the toxic compounds we are exposed to, has an impact on our own longevity.
Now researchers from Stanford University believe they have found that this also effects the longevity of our descendants.
The researchers tested roundworm in the laboratory by modifying the expression of any three key proteins and they found it effected not only the worm but its descendants even though the original modifications are no longer present in the descendants.
The finding is the first to show that longevity can be inherited in a non-genetic manner over several generations, the researchers claim.
Professor Anne Brunet said: 'We are also curious as to whether environmental factors that can affect longevity, like calorie restriction, could also affect subsequent generations.'
Humans share similar proteins with those studied in the worms and while the team recognise more work is needed the findings suggest that modifications that occurred in our great-grandparents time have an effect on our own life spans.
Epigenetics is the term which describes when organisms change their gene expression in response to environmental cues without changing the underlying sequence of their DNA.
Chromatin, the tightly coiled complex of DNA and proteins that keeps the genetic material firmly packed in the cells’ nucleus, can be modified by addition or removal of chemical tags on proteins or DNA itself.
While these chromatin modifications are normally reset between generations during the process of reproduction, this study suggests that such reprogramming is incomplete in some cases.
Previous studies have already found that modifying several chromatin regulators can increase the life span of a laboratory roundworm by as much as 30 per cent.
These chromatin regulators control life span by functioning at least in part in the worm’s reproductive system.
Lead author Eric Greer bred the worms in such a way that their descendants would no longer have the mutations.
He found that the descendants with normal levels of expression of the three proteins, but with ancestors that were deficient for them, still lived longer than descendants from un-mutated ancestors.
This longer life span persisted, in some cases for up to three generations, but did eventually disappear and the worms reverted to a normal life span.
Professor Brunet said: 'We still don’t know the exact mechanism of this epigenetic memory of longevity between generations.
'We hypothesise that when the parental generation is missing key components that normally regulate chromatin, epigenetic marks are not completely reset from one generation to the next in the germ line, thereby inducing heritable changes in gene expression.
'It will be very interesting to understand how this happens.'
The study is published in the online journal Nature.