I’m a planner at a digital agency, and I find myself thinking about this an awful lot. Admittedly, it’s not a question I ever get asked directly, but I do think it’s the question behind a lot of the questions I have to address.

Because when we build digital products and services — and, if we must, advertising — we base a lot of our decisions on the patterns of behaviour we can observe online. Identifying and understanding those patterns is one of the things I find most interesting about my job.They exist at the crossroads of human impulse and technological innovation. Each is the result of an intricate and unique set of factors, the unpicking of which helps me understand a little more each time about the social web and, perhaps, what’s happening to us.

A symbiotic relationship exists between the urges we experience and what technology allows us to do. They grow together.

Yes, we feel some sort of fundamental call to do the things that social platforms allow us to do. We have always wanted to connect, to share our stories, to find common interests and seek belonging in new places.

These urges are not new, the argument goes. They are just newly possible in faster, easier, further-reaching ways.

And yet this seems to miss something. Certainly it always leaves something niggling at the back of my mind.

On one hand we accept the notion that digital has changed everything. On the other, we agree that it hasn’t at all.

The truth, I expect, is somewhere in between. We enjoy new capabilities that help us fulfill ancient human needs. But we enable those capabilities using technology that in turn creates new expectations.

As digital people we’re supposed to look into the future. But sometimes it’s helpful to look back, to work out what we used before we could do what we now take for granted.

This week I posted on Instagram a photo of my son on his first day of Junior school. Thirty years ago, when I was his age, this particular milestone, had it been captured as a photograph, would have remained contained within a photo album — y’know, the physical kind — likely to be browsed by immediate family only, or perhaps shown to girlfriends twenty years into the future.

In fact, if in 1983 that album had been shown to anyone else outside the family, its owners would have been considered bores, or a bit weird.

While the technology existed to make photography more accessible, no technology yet existed to make sharing those photos any easier. So it just looked like you were trying too hard. Or were too interested in yourself.

In the last season of Mad Men there’s a scene where Megan insists on showing her neighbours photographs of the Drapers’ recent trip to Hawaii. She uses a carousel, the like of which her husband pitched so beautifully when he was married first time round.

In 1968 sharing your photos — at least, a certain type of photo — was perhaps still a cool thing to do. Was this because ‘sharing’ was more of a thing in the 1960s?

I don’t think so.

Or was it because the technology that enabled it (the travel, the processing, the projecting) was still relatively rare, and therefore held a certain cache?

It seems to me that the sharing impulse may be less of a defining factor in people’s behaviour than the technology which enables it.

Or,to put it more accurately, less of a factor than the collectively held perception of the technology that enabled it.

Somewhere between 1968 and 1983 foisting your personal snaps on people became passe. Somewhere between 1983 and now it became the norm again.

This is fashion, not fundamentals. Perhaps the ebb and flow of technological uptake — now new, now commonplace — can both dampen and encourage our natural impulses, depending on the role the technology plays in our lives.

Can our preparedness to share aspects of our lives with others really be innately tied to technological capability? Or perhaps it’s that the social signals we want to send can be manifested in the way we choose to use technology.

Sometimes we want to fit in, at others we want to set ourselves apart.

Which makes it about fundamentals after all.

There aren’t any easy, consistent answers. But then, that’s what to me is endlessly fascinating. As I said earlier, each pattern of behaviour we observe contains its own logic. It’s up to us as planners to decode these patterns. To unpack the fundamental from the newly possible; the crowd impulse from individual story.

This week I read John Lanchester’s essay on the London Underground, part of a series of books published to celebrate the Underground’s 150th anniversary last year.

A passage on the Tube’s relationship to the growth of London struck me as a highly appropriate analogy. The rapid growth of both are connected, much like the emergence of new behaviours is closely related to spread of web technologies .

The Underground is what gave the city its geographical spread, its population growth,its clusters of spaces and places. The new Underground stations became the places around which the city grew: they were the first gravitational mass, like the clusters of debris in the nascent solar system, which agglomerated and grew and thickened and became the planets. The Underground stations in the early years of the network were these initial clusters of mass.

Lanchester then describes a photo of Golders Green station in 1907, before the suburb itself really existed, sealing the point.

The growth of the city created the need for a new transport network; and the growth of that network became fundamental to the growth of the city. London created the Underground, and the Underground created London.

I see my job as spotting and understanding those clusters of spaces and places, at the crossroads of human impulse and technological advancement.

Whether first gravitational mass or agglomerated planet, these clusters can always tell us as much about people as they tell us about the web.