Judith Shulevitz, in the May 13, 2013 New Republic has an interesting read “The Lethality of Loneliness.”
“Psychobiologists can now show that loneliness sends misleading hormonal signals, rejiggers the molecules on genes that govern behavior, and wrenches a slew of other systems out of whack. They have proved that long-lasting loneliness not only makes you sick; it can kill you. Emotional isolation is ranked as high a risk factor for mortality as smoking. A partial list of the physical diseases thought to be caused or exacerbated by loneliness would include Alzheimer’s, obesity, diabetes, high blood pressure, heart disease, neurodegenerative diseases, and even cancer—tumors can metastasize faster in lonely people….
“To the degree that loneliness has been treated as a matter of public concern in the past, it has generally been seen as a social problem—the product of an excessively conformist culture or of a breakdown in social norms. Nowadays, though, loneliness is a public health crisis. The standard U.S. questionnaire, the UCLA Loneliness Scale, asks 20 questions that run variations on the theme of closeness—“How often do you feel close to people?” and so on. As many as 30 percent of Americans don’t feel close to people at a given time….
“What He [God] wanted is for us not to be alone. Or rather, natural selection favored people who needed people. Humans are vastly more social than most other mammals, even most primates, and to develop what neuroscientists call our social brain, we had to be good at cooperating. To raise our children, with their slow-maturing cerebral cortexes, we needed help from the tribe. To stoke the fires that cooked the meat that gave us the protein that sustained our calorically greedy gray matter, we had to organize night watches. But compared with our predators, we were small and weak. They came after us with swift strides. We ran in a comparative waddle.
“So what would happen if one of us wandered off from her little band, or got kicked out of it because she’d slacked off or been caught stealing? She’d find herself alone on the savanna, a fine treat for a bunch of lions. She’d be exposed to attacks from marauders. If her nervous system went into overdrive at perceiving her isolation, well, that would have just sent her scurrying home. [John] Cacioppo thinks we’re hardwired to find life unpleasant outside the safety of trusted friends and family, just as we’re pre-programmed to find certain foods disgusting. “Why do you think you are ten thousand times more sensitive to foods that are bitter than to foods that are sweet?” Cacioppo asked me. “Because bitter’s dangerous!”
The article, well worth a read, discusses issues like that only about half of loneliness is hereditary, what areas of the brain light up when we are socially snubbed (the same portion that registers physical pain, i.e., the dorsal anterior cingulate cortex), what has been learned about the impact of the absence of loving parents on loneliness from the isolating experience of Russian orphans; and how Nobelist James Heckman is finding that many low SES children bear loneliness scars from poor parenting growing up (that is akin to the impact found by Steve Suomi and Harry Harlow on isolated rhesus macaques).