People are among the most social creatures on earth. Even in their most primitive state, people naturally form dense webs of social and family ties that sustain and drive their culture and their very survival. This drive for human connections is as old as recorded history. The second chapter of Genesis asserts, “It is not good that the man should be alone.”

Yet a new study published in the American Sociological Review¹ reveals that more people in the United States appear to be more alone than at any time in recent history. According to the latest census figures, 27.2 million households — a quarter of the total — are occupied by only one person.

In addition, while Americans reported having three close friends in 1985, today they report having only two. The number of people who claim to have no friends went from 10 percent in 1985 to 25 percent in 2004. Almost 20 percent said they had only one deep relationship, and often that person was a spouse.

And that may be the most worrisome situation, since such a person may be left completely alone when the husband or wife dies.

Loneliness is not just an inconvenience. According to an Associated Press² report, numerous experts have shown that loneliness increases the risk of disease and depression and suppresses the immune system.

The National Co-Morbidity Survey shows that men suffer more than women after the death of a spouse. Men are typically not as good at being alone. In addition, they have not usually built up the same social networks that women create, which can take a toll on their health. For example, Harvard researchers last year discovered elevated levels of blood markers for heart disease in men who live alone.

Among people of both genders, living alone appears to be linked to poor health. A recent study in the journal Psychology and Aging³ shows that the risk of high blood pressure increases dramatically in the more than 11 million Americans over 50 who are lonely.

Not just the elderly are at risk. Divorce and job relocation contribute to isolation, and even college students may find themselves alone in an unfamiliar environment. The National Institute on Aging found that even younger adults who are lonely show deterioration of blood vessels that could lead to high blood pressure later in...