• heart disease

Homo sapiens is among the most inherently social species on Earth. A proclivity to closely collaborate with other individuals is an instinctive character trait of humans, and this accounts for much of our success as a species. The new study by Chen and colleagues,1 an epidemiological cohort study of 10 000 Swedish twins, found that living alone, regardless of the reason, was associated with a higher risk of cardiovascular disease (CVD) and a shorter leucocyte telomere length (an established biomarker of ageing). However, the observed telomere shortening did not account for the increased risk of CVD among individuals living singly.1

The hypothesis that marriage confers protection against premature mortality and CVD was first proposed over a century ago. Across European, Asian and American cohorts, marriage has been associated with a 1.2-fold to 2.5-fold decreased mortality when compared with widowed, divorced or never-married individuals.2 Also, a prospective cohort of 94 062 Japanese demonstrated a three-fold increased CVD mortality in never-married men when compared with married men.2 A cohort study of 734 626 healthy women reported a significantly lower risk of coronary heart disease (CHD) mortality among married/cohabitating compared with unmarried women, with a relative risk of 0.72 (95% CI 0.66 to 0.80, p<0.0001).2 3 The tendency for marriage to lower mortality extends to divorced individuals. In the Charleston Heart Study, all-cause mortality was lower after remarriage compared …