Hanging out with younger, healthier people might help the elderly to live longer, suggests a study of fruit flies.
The research also supports the notion that old people are more likely to thrive if with a younger peer group, or with their children and grandchildren, than if they are with their aged peers in a home.
Scientists have already gathered a range of evidence that having a social network is healthier than leading a solitary life: the healthy effects of attending church could be as significant as those enjoyed by people who give up smoking, according to one study of 4,000 elderly people in North Carolina.
Another study at the University of Chicago found that loneliness is a major risk factor in increasing blood pressure and could raise the risk of death from stroke and heart disease.
However, the underlying reason why being sociable has health effects have not been well understood. Now, fruit flies are set to provide the answer, after the discovery that fast-ageing flies that socialise with normal flies live longer than if they live with their peers.
In a study published in the Proceedings of the National Academy of Sciences, Drs Hongyu Ruan and Prof Chun-Fang Wu of the University of Iowa used the fruit fly Drosophila melanogaster to examine the molecular networks that govern the effects of social interactions on the ageing process.
he authors grew a particular strain of mutant fly with greatly reduced lifespan and raised the flies in the same vial as normal fruit flies.
What was striking was that the mutant flies that lived with normal flies lived survived nearly twice as long as mutants housed with other mutants.
In addition, flies with shorter lifespans housed with the normal flies had improved physical responses and better survived environmental stresses compared to those that remained among the mutant population, according to the authors.
The mutation that cuts lifespan, by interfering with an enzyme that mops up harmful radicals, mirrors deficits in a number of age-dependent diseases in humans, including Parkinson's, Huntington's, and Alzheimer's diseases, leading the team to suggest that their research may aid in therapies for these illnesses.
"Our results provide a definitive case of beneficial social interaction on lifespan and a useful entry point for analysing the underlying molecular networks and physiological mechanisms," they conclude.