Londoners over the age of 31, it appears, are really bad at socialising. Once our 30s bite, we prioritise home comforts and takeaways over nights out with friends. On the face of it, this seems to go against our essentially social nature.
If human beings really are social animals, then we should all naturally favour social activities. Yet have you ever watched the muddy hordes of Glastonbury, fought your way through a crowded pavement of after-work drinkers, or opened an invitation to a friend's wedding in Majorca with distaste rather than envy or anticipation?
And if you think about it, wasn't Michelangelo up on that scaffolding in the Sistine Chapel by himself for four years? With his interest in anatomy, he probably spent more time looking at dead or marble or painted humans than real ones.
All of this tells us that in people there is clearly a desire to not socialise that's just as natural as the tendency to seek the company of others.
In fact, for much of our lives there's a kind of equilibrium balancing our need and desire to socialise with our ability to do so. Take for instance people at school or in other kinds of education: they're in an optimal setting for making friends.
Being in a single institution for six hours a day throughout our formative years socialises us all. No wonder that in a recent online survey 72% of adults said it was easier to make friends before they left full-time education.
When you get into your 20s and 30s, work usually provides the main focus to your social life. But not everyone wants to sit all day at a desk and then stand all evening outside a pub. There's the pull of the gym after work rather than a bar crawl, or that exhibition at all the museums open late on Fridays. You can go to an exhibition with friends, but then it's hard to really focus on the art without being rushed or distracted.
And then there's parenthood. Even if having a baby can kill your pre-pregnancy social life, a child brings couples into contact with others who have children. Children are naturally worked into the socialising process and often enrich it.
So it is that the nature of socialising, and your desire for it, ebbs and flows throughout your life.
Of course, circumstances are never the whole story. The Oxford English Dictionary gives us an additional, intriguing definition of socialising: "to make (someone) behave in a way that is acceptable to their society".
Right away the instinctive move away from others seems less like an unhealthy symptom of antisocial behaviour than a rejection of conformity. Man might be a social animal, but he's one who becomes ever more aware of his individuality as he ages. And part of growing as an individual is learning to enjoy your own company.
Having said all that, our society is afflicted by an epidemic of loneliness. Distracted from friendship by the pressures of present-day living, no wonder 63% of adults would like to have more close relationships. In older adults the problem is even more acute, with loneliness becoming increasingly recognised as a major public health issue.
So how does a young person with plenty of friends become an isolated, lonely older adult? The answer could be chillingly simple. A 2014 clinical psychology PhD thesis identified several factors which stop older people leading active social lives, with one of the most far-reaching being the loss of social contacts over time.
The scariest part of this process is its gradual nature. Sure, as we age, our partners and friends move away or die. But if we don't make new friends or maintain real-world connections with old ones, our opportunities for social activity are apt to disappear so subtly we don't notice. Until, that is, we suddenly find ourselves alone and lonely.
I'm not saying we should all be social butterflies all of the time: there's a kind of wisdom in rolling gracefully with the natural social patterns which emerge in the different stages of our lives. But we－introverts and extroverts alike－should all be aware that to spend time with the people we truly value is to make an investment in our long-term happiness and wellbeing.
Which means we (at least sometimes) need to conquer our dread of going out. Even if it is normal.
Daniel Lewis is the founder of Loose Ends App.