A new study analyzed data from one of the oldest and most complete registries of information about twins in the world—2,932 pairs of same-sex twins born in Denmark between 1870 and 1900—and compared their lifespans to that of the general population.
The authors found that at nearly every age, identical twins survived longer than fraternal twins, who, in turn, had greater longevity than the general population.
Why do twins live longer?
We already know that a similar longevity effect has been found for marriage: Married people tend to be healthier than unmarried people and live longer. However, drawing clear conclusions from marriage data is complicated because it is unclear whether marriage itself makes people healthier or whether healthier people choose to get and stay married. Because twins have no choice about their twinhood, it is easier to tease out the contributing factors to their longevity.
The researchers concluded twins’ greater longevity results from three factors:
Full disclosure: I am an identical twin and have an extremely supportive relationship with my brother. However, the findings of this study demonstrate the importance of close, life-long social bonds of any kind. True, twins have the advantage of built-in social and emotional support, but similar benefits can also be derived from having a life-long best friend, a long and supportive marriage, or an extremely close relationship with anyone we choose to share our lives with. Indeed, having a close circle of friends or a tight-knit community has also been found to increase longevity.
Therefore, what this study actually illustrates is the importance of maintaining close and highly supportive relationships. They not only enrich our lives, they also extend them.