How much does social interaction influence how long we live? In Cure: A Journey into the Science of Mind Over Body, Jo Marchant looks into the “Blue Zones” of the world — regions where people tend to live longer than elsewhere.
Living nearby was 99-year-old Francesca Castillo, who cut her own wood and twice a week walked a mile into town. And there was 102-year-old Ofelia Gómez Gómez, who lived with her daughter, son-in-law and two grandchildren. When Buettner’s team visited, she recited from memory a six-minute poem by Pablo Neruda. All of the elderly people they saw were still mentally, physically and socially active, despite their advanced age.
The team reported in 2013 that Nicoyans’ telomeres are indeed longer than those of other Costa Ricans. Their impressive life expectancy isn’t a statistical fluke but a real biological effect, in which their cells look younger than expected for their age. The size of the effect was equivalent to changes caused by behavioral factors such as physical exercise or smoking.
To investigate why the Nicoyans’ telomeres are so long, Rosero-Bixby and Rehkopf analyzed the effects of everything from the residents’ physical health and level of education to their consumption of fish oils. Diet makes no apparent difference, and the Nicoyans are worse off than other Costa Ricans when it comes to health measures such as obesity and blood pressure. Their slower aging doesn’t seem to be a consequence of genes either — Nicoyans lose their longevity advantage if they move from the region. And it isn’t money: richer individuals actually have shorter telomeres.
But there are some clues. Rehkopf and Rosero-Bixby found that Nicoyans are less likely than other Costa Ricans to live alone, and more likely to have weekly contact with a child. Such social connection seems crucial. The telomere length difference is halved among Nicoyans who don’t see a child each week, and if they live alone, they lose their advantage completely.
Other studies have found that Nicoyans have greater psychological attachment to family than residents of Costa Rica’s capital, San José. So Rehkopf and Rosero-Bixby speculate that close family ties might protect Nicoyans against life stress that would otherwise shorten telomeres. Despite their poverty, strong social bonds keep them young.
After adjusting for age and other risk factors, adults who reported fewer social relationships and activities were around twice as likely to die over the next decade. Their lack of social bonds, it seemed, was killing them early.
In 2010, U.S. researchers analyzed 148 studies following more than 308,000 people and concluded that lacking strong social bonds doubles the risk of death from all causes. That confirms House’s finding that in Western societies, at least, social isolation is as harmful as drinking and smoking, and suggests that it is actually more dangerous than lack of exercise or obesity.
Of course, when we have social support, we live more healthily. We have someone to cook us meals, take us to the doctor and nag us not to drink or smoke. This has a powerful effect, but the difference in death rates persists even after accounting for it. People who have warm relationships, rich social lives, and who feel like they are embedded in a group “don’t get as sick, and they live longer,” says Charles Raison, a psychiatry professor and mind-body medicine researcher at the University of Wisconsin-Madison. “It’s probably the single most powerful beahvioral finding in the world.”
Compared to the 1950s, they pointed out, U.S. adults in the 1970s were less likely to belong to voluntary organizations, less likely to visit informally with others and more likely to live alone.
According to the 2011 census, 32 million people in the country now live alone; that’s 27% of households, up from 17% in 1970. When researchers asked a representative sample of Americans in 1985 how many confidantes they had, the most popular answer was three. When the study was repeated in 2004, the most popular answer — given by 25% of respondents — was none.