The idea that social relationships affect health and longevity has enjoyed considerable popularity ever since the seminal paper by Berkman and colleagues showed a protective effect of social networks on survival.¹ Numerous studies have reported that being connected to people seems to confer various forms of health benefit. The paper by Giles and colleagues in this issue of the journal follows this line of research,² showing that social relationships remain an important health resource into very old age. The paper further illustrates that this health benefit may be restricted to social relationships that tend to be more discretionary, such as those with friends and relatives other than children. Similar findings have been reported for other important health outcomes in older age, both by this group of investigators³ and others.^4,5 Yet as appealing the idea is that social relationships, and friendships in particular, are good for our health, as elusive remains our understanding of why or how this is so.

The list of answers to this question is potentially long and complex. The usual suspects have been covered previously, and are nicely summarised in the paper by Giles et al.² There is little doubt that declining health affects the ability …