Mr. Hobbs and the paper’s other authors matched records from California’s Department of Public Health with those of California Facebook users, preserving privacy by aggregating the data before analyzing it, the release said. All of the subjects of the study were born from 1945 to 1989.

The paper found that people with large or even average social networks lived longer than people who had very small social networks. It was “a finding consistent with classic studies of offline relationships and longevity,” the release said.

The paper itself acknowledges the study’s “many limitations,” saying that Facebook is unique among social media websites and that its data might not be more broadly applicable. It also points out that its findings represent a correlative relationship as opposed to a causal one: There is no evidence in the paper that using Facebook has any direct effect on a person’s health.

James Fowler, a professor of public health and political science at the University of California, San Diego, and another of the paper’s authors, said he had been surprised that requesting the friendship of others was not found to be associated with a longer life span.

“I had hoped we would find that reaching out to others was associated with better health,” he said.

The new result, Mr. Fowler explained, suggested that researchers who had previously found that people with more friends were healthier might have misunderstood the relationship between sociability and health. It may be, he said, that “the reason why people with more friends are healthier is because healthier people have more friends,” which would suggest that “it may be harder than we thought it was to use social networks to make people healthier.”

Nathan Jurgenson, a sociologist and a researcher for Snapchat, said in an email that the paper provided much evidence against the idea that connections made online exist separately from the “real world,” as if the internet did not exist within the broader universe.

But he pointed out that the study itself, even in providing evidence to support the idea that the internet is not different from “real life,” used language that reinforced the binary view.