Benefits of lifelong social support?
According to a new study published in PLOS ONE, an analysis of nearly 3,000 same-sex twin pairs in Denmark found that twins live longer than the general population of singletons.
"We find that at nearly every age, identical twins survive at higher proportions than fraternal twins, and fraternal twins are a little higher than the general population," lead author David Sharrow, a postdoctoral researcher at the University of Washington, said in a press release.
This analysis is the first to look at life expectancy among twins versus the general population, but the results could have implications for twins and non-twins alike — close social connections could harbor a significant health benefit.
Using data from the Danish Twin Registry, the researchers looked at 2,932 pairs of twins who were born between 1870 and 1900, so all had completed their lifespans. Comparing the twins’ ages at death with data for the overall Danish population, the researchers found that the peak benefit of having a twin sibling occurred in the mid-40s. If 84 out of 100 boys in the general population were still alive at age 45, the number for twin boys was 90. For female twins, the peak benefit occurred in their early 60s.
"There is benefit to having someone who is socially close to you who is looking out for you," Sharrow said. "They may provide material or emotional support that lead to better longevity outcomes."
The team also analyzed a mortality model using the twin data — separating acute causes of death, like accidents or behavior-related causes, from natural causes in old age — and stumbled upon an unexpected discovery.
While female twins had a lower mortality rate for earlier, acute causes, male twins benefitted from an overall longevity boost. Sharrow suspects this may reflect the “immediate and cumulative effects of male twins making healthier choices,” according to the release.
"Males may partake in more risky behaviors, so men may have more room to benefit from having a protective other -- in this case a twin -- who can pull them away for those behaviors," Sharrow said.
"There is some evidence that identical twins are actually closer than fraternal twins," he continued. "If they're even more similar, they may be better able to predict the needs of their twin and care for them."
The authors note that these findings should be replicated in other datasets of twins, since this study only included data on Danish twins.
However, the results could have implications for the general population.
"Research shows that these kinds of social interactions, or social bonds, are important in lots of settings," Sharrow concluded. "Most people may not have a twin, but as a society we may choose to invest in social bonds as a way to promote health and longevity.”