Human societies, at all times and places, have organised themselves around the will to live with others, not alone. But not any more. During the past half-century, our species has embarked on a remarkable social experiment. For the first time in human history, great numbers of people – at all ages, in all places, of every political persuasion – have begun settling down as singletons. Until the second half of the last century, most of us married young and parted only at death. If death came early, we remarried quickly; if late, we moved in with family, or they with us. Now we marry later. We divorce, and stay single for years or decades. We survive our spouses, and do everything we can to avoid moving in with others – including our children. We cycle in and out of different living arrangements: alone, together, together, alone.
But despite the worldwide prevalence, living alone isn't really discussed, or understood. We aspire to get our own places as young adults, but fret about whether it's all right to stay that way, even if we enjoy it. We worry about friends and family members who haven't found the right match, even if they insist that they're OK on their own. We struggle to support elderly parents and grandparents who find themselves living alone after losing a spouse, but we are puzzled if they tell us they prefer to remain alone.
In all of these situations, living alone is something that each person, or family, experiences as the most private of matters, when in fact it is an increasingly common condition.
So what is driving it? The wealth generated by economic development and the social security provided by modern welfare states have enabled the spike. One reason that more people live alone than ever before is that they can afford to. Yet there are a great many things that we can afford to do but choose not to, which means the economic explanation is just one piece of the puzzle.
Another driving force is the communications revolution, which has allowed people to experience the pleasures of social life even when they're living alone. And people are living longer than ever before – or, more specifically, because women often outlive their spouses by decades, rather than years – and so ageing alone has become an increasingly common experience.