The benefits of having a twin go far beyond always having someone with whom to plan a birthday party. A new study suggests having a twin may actually help you live longer than most, and those with an identical twin may live the longest.

At nearly every age, twins outlive the general population, with identical twins outliving us all. Overall, male twins had the biggest longevity advantage as they had both a lower mortality rate for acute causes, such as accidents in their early years, and for natural causes past age 65, Futurity reported. The reason for this, however, has little to do with DNA and more to do with having a constant companion.

“There is benefit to having someone who is socially close to you who is looking out for you,” lead author of the study David Sharrow, a University of Washington postdoctoral researcher, told Futurity. “They may provide material or emotional support that lead to better longevity outcomes.”

But why do male twins outlive female twins when the opposite is true for singletons? For this, the team has another hypothesis.

“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,” said Sharrow.

The research also suggests that identical twins may outlive fraternal twins simply because these types of siblings tend to be the closest.

Health Benefits Of Social Bonds

The study is based on data from the Danish Twin Registry. For their research, the study authors looked at 2,932 pairs of same-sex twins who were born in Denmark between 1870 and 1900, and survived past 10 years of age. These numbers were then compared to the age at death for the general Danish population.

The findings help to show the important role social relationships play in our physical health. This is the same theory behind past research suggesting that married couples live longer than singletons. For example, a 2014 report found that married men were likely to live longer than single men or cohabitating men. However, it’s hard to pinpoint just one reason for this increased lifespan. For example, the research found that married men are more likely to visit the doctor than single men, and they are also more likely to have someone tend to them if and when they did fall ill. The same factors may carry over to twin relationships.

“There is benefit to having someone who is socially close to you who is looking out for you,” Sharrow added. “They may provide material or emotional support that lead to better longevity outcomes.”

The team hope that better understanding into how social interactions between twins helps to preserve their health will help them extend this benefit to others.

Source: Sharrow DJ, Anderson JJ. A Twin Protection Effect? Explaining Twin Survival Advantages with a Two-Process Mortality Model. PLOS One. 2016

Read More:

When It Comes To Health, Being Married Wins: People With Spouses Live Longer Than Cohabiting Partners: Read Here

Married Vs Single: What Science Says Is Better For Your Health: Read More