Having an identical twin is good for more than orchestrating elaborate mistaken identity capers and pranking random people on the NYC subway. According to a recent study in the journal PLOS One, twins may actually live longer than the general population.

Researchers at the University of Washington used the Danish Twin Registry to analyze 2932 pairs of Danish twins born between 1870 and 1900 who had survived past the age of 10. They found that both fraternal and identical twins lived longer than singletons, though identical twins lived the longest.

The greatest benefit of having either an identical or fraternal twin occurred for men in their mid-40s and women in their 60s, according to the research. While 84 percent of the general male population was still alive at 45, a full 90 percent of male twins were alive at that age. Female twins in their early 60s, meanwhile, led the general population by 10 percentage points.

Researchers aren’t sure why twins have lower mortality rates than others, though they believe the cause is likely social rather than biological. They say it may be akin to the so-called marriage protection effect. “There is benefit to having someone who is socially close to you who is looking out for you,” researcher David Sharrow explains. “They may provide material or emotional support that lead to better longevity outcomes.”

Sharrow notes that more research is needed to substantiate the connection between twins and longevity, especially since the study’s data centered exclusively on people born in Denmark in the late 19th century. However, he believes that studying twins could be the key to understanding how strong social bonds can increase the life spans—and quality of life—of both twins and singletons. “Research shows that these kinds of social interactions, or social bonds, are important in lots of settings,” he explains. “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.”

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