London: Intelligent people outlive their less clever peers because genes that make one intelligent may also be associated with a longer lifespan, according to a new study.
Scientists have known that cleverer people outlive their less intelligent peers. Most explanations for this have argued that it is down to status effects.
The hypothesis is that more intelligent people earn more and have higher status, both of which would lead them to also have better health.
However, a new study by scientists at the London School of Economics has found that the link between intelligence and lifespan is genetic, 'The Times' reported.
The scientists looked at the differences in longevity between identical and non-identical twins, using studies from Sweden, the US and Denmark.
Identical twins share all their genes, while non-identical twins share ? on average ? half of them. They are often used in genetics studies to differentiate between environmental and inherited effects, because they are typically brought up in the same way.
The scientists recorded the difference in intelligence between twins, and their ages at death.
They found that in both sorts of twins the brighter of the two lived longer, but in non-identical twins the effect was far greater. From this they calculated that 95 per cent of the link between intelligence and lifespan was genetic.
"Our research shows that the link between intelligence and longer life is mostly genetic. So, to the extent that being smarter plays a role in doing a top job, the association between top jobs and longer lifespans is more a result of genes than having a big desk," said Rosalind Arden, a research associate at the LSE.
"However, it's important to emphasise that the association between intelligence and lifespan is small. So you can't, for example, deduce your child's likely lifespan from how he or she does in their exams this summer," Arden said.
Arden said that the research did not explain how the genetic link between intelligence and lifespan works.
"It could be that people whose genes make them brighter also have genes for a healthy body. Or intelligence and lifespan may both be sensitive to overall mutations, with people with fewer genetic mutations being more intelligent and living longer," Arden said.
The study is published in the International Journal of Epidemiology.