People with higher-than-average IQs may attend prestigious colleges, be the recipients of large scholarships, or easily find a profession in their chosen career. As it turns out, the benefits of intelligence may extend far beyond academic or career progress. In every population studied so far—with most studies including people from Western democracies—researchers have found that high IQ test scores in childhood correlate with a longer life.
Though scientists have offered a number of explanations for this correlation, a clear answer has been remarkably elusive. A study published in the International Journal of Epidemiology, though, argues that the phenomenon is likely genetic.
Why Intelligence Might Mean a Longer Life
Twin studies have long been used to estimate the heritability of a trait. Heritability is a measure of the degree to which genetic differences explain the differences in a trait between people, not an assessment of which portions of a trait are genetic in any single person. To explore the genetic connection between intelligence and long life, researchers pulled data from three different twin registries: 377 pairs of male veterans from the NAS-NRC US World War II Twin Registry, 784 pairs of twins from the Danish Twin Registry, and 246 pairs of twins from the Swedish Twin Registry. The sample included a total of 2,814 people.
The differences between twins were most pronounced among fraternal twins. Fraternal twins share 50% of their DNA, just like other siblings, but identical twins share 100% of their DNA. Thus researchers would expect more differences among fraternal twins, since they are less genetically similar.
Though the researchers confirmed a link between intelligence and long life, the correlation was a relatively small one. It is not possible to guess how long a person will live based solely on his or her intelligence. Moreover, measures of intelligence vary, and the very concept is increasingly controversial. Some people deemed less intelligent live longer than their counterparts who were determined to have higher IQs.
The researchers did not independently assess a genetic basis of intelligence, so the study is a measure of the heritability of intelligence and longevity together, not intelligence as a standalone trait.
- Arden, R., Luciano, M., Deary, I. J., Reynolds, C. A., Pedersen, N. L., Plassman, B. L., … Visscher, P. M. (2015). The association between intelligence and lifespan is mostly genetic. International Journal of Epidemiology Int. J. Epidemiol. doi:10.1093/ije/dyv112.
- Deary, I. (2010, October 28). Why do smart people live longer. Retrieved from http://www.project-syndicate.org/commentary/why-do-smart-people-live-longer
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