How a Thriving Social Life Can Boost Lifespan

May 27, 2008 — -- They say you are only as old as the woman (or man) you feel – now we might be closer to understanding why.

It has been suggested that humans and other vertebrates live longer if they have more social interactions, and now this has been verified – in fruit flies.

Chun-Fang Wu and Hongyu Ruan at the University of Iowa in Iowa City studied fruit flies with a genetic mutation that reduces their lifespan by interfering with an enzyme that mops up dangerous free radicals.

The same enzyme is implicated in age-related diseases like Alzheimer's and Parkinson's in humans.

Mutant flies that shared a home with younger flies, or non-mutants, lived longer and were more mobile than those sharing a home with similar-aged flies. They were also more resistant to the effects of extreme physical exertion, heat and oxidative stress.

Courtship and aggression

Impairing the movement or activity of younger flies reduced this effect, suggesting that social interaction with the younger flies through courtship, aggression, or grooming, plays a key role in increasing the lifespan of the older flies. "Social activity is the key," says Wu.

Keeping the flies in the dark, so they could not see each other, also reduced the effect.

The next step is to unravel how these social interactions override the mutant gene at the molecular level. In doing so, Wu hopes to understand how similar interactions could benefit ageing humans.

"This study shows that the lifespan of these flies is plastic and can be conditioned by social interactions, corroborating the notion that human patients of certain age-dependant neurological diseases may be benefited by an appropriate social environment," he says.

However, Wu has studied several genes that influence lifespan in fruit flies, and not all of them can be overridden by social interaction, he says.

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