‘Thefacebook is an online directory that connects people through social networks at colleges. We have opened up Thefacebook for popular consumption at Harvard University. You can use Thefacebook to: search for people at your school; find out who are [sic] in your classes; look up your friends’ friends; see a visualization of your social network.”

On 4 February 2004, this rather clunky announcement launched an invention conceived in the dorm room of a Harvard student called Mark Zuckerberg, and intended to be an improvement on the so-called face books that US universities traditionally used to collect photos and basic information about their students. From the vantage point of 2019, Thefacebook – as it was then known – looks familiar, but also strange. Pages were coloured that now familiar shade of blue, and “friends” were obviously a central element of what was displayed. However, there was little on show from the wider world: the only photos were people’s profile pictures, and there was no ever-changing news feed.

Everything on offer was centred on the lives of students: first at Harvard, then at Columbia, Stanford and Yale. On the face of it, the focus was campus dating and a feature whereby users could send each other “pokes”, whose meaning was open to interpretation, thus increasing the fun.

Very quickly, though, something else happened. By the autumn of 2005, 85% of US college students were using the site with 60% of students visiting it daily. As they immersed themselves, Thefacebook tapped into the fierce social competitiveness that the US education system seems to be built on. As David Kirkpatrick’s definitive history The Facebook Effect explains, users of the new site began to fixate on perfecting the details of their profile, not just to date, but to make themselves more attractive as potential friends. This came down to a handful of imperatives: “Find exactly the right profile picture. Change it regularly. Consider carefully how you describe your interests.”

In fact, says Kirkpatrick, being a successful Facebooker soon became such a necessity that it began to affect choices people made in the real world: “Since everyone’s classes were listed, some students even began selecting what they studied in order to project a certain image of themselves. And many definitely selected classes based on who Thefacebook indicated would be joining them there.”

Facebook Twitter Pinterest Facebook creators Mark Zuckerberg (left) and Chris Hughes at Harvard in 2004, the year of its launch. Photograph: Rick Friedman/Corbis via Getty Images

Everyone, it seemed, was performing, and the basic idea was to do as much performing as possible. At the end of 2004, Thefacebook reached a million users; in September 2006, having renamed itself Facebook, it moved beyond campuses and high schools, and opened itself up to anyone over 13 with an email address. But a core tenet of its Harvard beginnings remained: the imperative for users to present the world with the most flattering impression of themselves.

Fifteen years after Facebook’s birth, it has 2.2 billion users, Zuckerberg sits on a fortune of about $55bn (£42bn), and this week the company posted a record profit of $6.88bn for the final three months of 2018. And we know one other thing for sure: tangled up in its success is the fact that people lie about themselves on Facebook, as they do on other social media platforms. In 2016, when the market research firm Custard surveyed 2,000 people in the UK, it found that only 18% of them said their Facebook profile accurately represented them, 31% said the face they presented on Facebook boiled down to “pretty much my life but without the boring bits”, and 14% said Facebook made them look “much more” socially active than they were. Men, it seemed, were more likely than women to knowingly depart from the truth: 43% admitted to fabricating some aspect of their online selves.

That said, there is plenty of evidence of the same everyday deceit on the other side of the gender divide. Six years ago, the market research company OnePoll found that a third of women it surveyed admitted to “dishonesty” on social media. Almost one in four admitted to lying or exaggerating about key aspects of their life online between one and three times a month, and almost one in 10 said they lied more than once a week. Nearly 30% of women lied about doing something when they were really home alone, and 20% were not truthful about their holiday activities or their jobs.

On the face of it, this may not seem that revelatory. It is, perhaps, in the nature of our relationships with other human beings that we work desperately hard on our outward presentation, and sometimes fall into a kind of performance that leads inexorably towards fibs.

However, the Facebook age marks a break from traditional human behaviour in key aspect. In the past, we could regularly take a break from acting, and revert to some sense of our private, authentic selves. Now, as we constantly prod at our smartphones and feel the pull of their addictive apps, when does the performing ever stop?

Along with Russian interference in elections, fake news, Facebook’s approach to hate speech and its insatiable appetite for personal data, this is surely one of the most malign ways in which its presence in our lives is playing out.

What its innovations have done to the divide between our social and private lives highlights a mess of stuff to do with the true meanings of intimacy and privacy, and something that goes even closer to the heart of what it is to be human: who we really are beyond the attention and judgments of others, and whether we even know any more.

This demise of the barrier between our public and private selves is particularly relevant to people going through that stage of life when the very idea of “self” is still in flux: the often difficult period from the stirrings of adolescence to the mid-20s (and, if you’re unlucky, even older). At that point, sensitivity to your peer group is at its height and an obsession with what some people call “social comparison” tends to run deep. We all know the basics: you desperately want to meet all the requirements of whichever code of cool is holding sway, and avoid mockery at all costs. Looks are at their peak of importance. So are clothes.

In her new doorstop-sized treatise on the dominance of Facebook and Google, The Age of Surveillance Capitalism, the American academic Shoshana Zuboff gets to the heart of why social media collides with this stage of life in a particularly toxic way. “Social media marks a new era in the intensity, density and pervasiveness of social comparison processes especially for the youngest among us, who are ‘almost constantly online’ at a time of life when one’s own identity, voice and moral agency are a work in progress,” she writes. “In fact, the psychological tsunami of social comparison triggered by the social media experience is considered unprecedented.” She calls this experience “life in the hive”, and rather chillingly characterises it as “being alive in the gaze of others because it’s the only life one has, even when it hurts”.

Facebook Twitter Pinterest We constantly prod our phones and feel the pull of their apps. Photograph: Odilon Dimier/Getty Images/PhotoAlto

I remember what it was like being 16, and the minefield of peer pressure, ridicule and keeping up with the cool kids I had to navigate. Coming home each afternoon and having long spells to unwind was essential – in fact, it was in these daily quiet periods that I began to get some vague sense of who I was. If you had told me that in the near future, the noise of school would emanate from an addictive device that compelled me to carry on performing for my peers until I fell asleep, I would probably have screamed. Yet this is now the everyday reality for millions of teenagers, and we all know the likely consequences.

According to a report published this week by the media regulator Ofcom, 70% of those aged 12 to 15 have at least one social media profile. Among those aged eight to 11, the figure is 18%. Ofcom says that children’s most visible accounts tend to “be more highly curated, showing a ‘picture-perfect’ self”. A substantial body of opinion links depression and anxiety to social media use, something routinely traced to online bullying and negative self-perception caused by reading other people’s online posts. According to the Millennium Cohort Study led by the Institute of Education, London (which follows the life experiences of 19,000 people born at the start of the 21st century), almost 40% of girls who spend more than five hours a day on social media show symptoms of depression; research in 2017had a negative effect by the Royal Society for Public Health recorded young people themselves suggesting that all the big social platforms on their mental wellbeing, something that health professionals said was bound up with increased feelings of inadequacy and anxiety.

In response, defenders of Facebook might argue that its popularity is declining among younger users, who now prefer Snapchat and Instagram. However, Facebook is still used by millions of young people and Zuckerberg’s company owns Instagram. There is also a sense in which Facebook has led the way in breaking down some of the behavioural distinctions between children, youths and adults, to the point that all social media users are acting like teenagers, and experiencing the same downsides of excessive use, whichever platform they favour.

Put another way, endless performance, the craven pursuit of approval and worrying about what other people think of us might be quintessentially adolescent behaviour, but millions of people of a much more advanced age are doing exactly those things on a minute-by-minute basis, usually via Facebook. And in that context, the 15th anniversary of Mark Zuckerberg’s invention might be a good time to take a step back, and consider whether we are suffering from a huge outbreak of collective arrested development, with all the pain and dysfunction that entails.

I don’t often use Facebook, but I am a habitual tweeter, and I know that I post too much, and that it gets in the way of far too many experiences. By the same token, I am not sure that repeatedly changing one’s Facebook profile picture in pursuit of two-word comments from your friends (such as “Gorgeous, babe”) is behaviour that does anyone any good, but it definitely doesn’t suit people much over 25. There is no need to write posts about what you just had for dinner, or the funny thing the dog did. Most of all, it seems incontestable that, whatever age we are, we need moments of quiet and introspection to reaffirm what it is to be alive, and that Facebook is something that too often spoils things.

This is particularly true of the way we enjoy other people’s creativity. A recent article on the music website the Quietus by the writer Jazz Monroe nails the essential point. “When we submit to a profound experience of art, it’s a rare reprieve from the everyday torrent of triviality and distraction,” he wrote. “Likewise, when you finish a great book, there’s supposed to be a moment when you reflect on it. But it’s so easy to just check your phone, or tweet some earnest statement about it.”

Facebook Twitter Pinterest Have we lost the ability to be alone? Photograph: Getty Images/Mint Images RF

Even in the company of other people, there are times when we need to withdraw into ourselves and savour an essentially private moment of transcendence. Gigs are a good example, which makes me think of a line from Radiohead’s 1997 song Karma Police, which I heard Thom Yorke sing a cappella to an entranced crowd at Glastonbury: “For a minute there, I lost myself.” But in such settings, Monroe says, smartphones and their apps are basically “alien interlopers carrying a ton of baggage”. He goes on: “Small concerts are not designed to outperform a £600 device containing the entire internet. That makes the radioactive slab of social energy in your pocket a cultural hazard. When you shoot a casual glance at its screen – perhaps unconsciously, out of undiagnosed boredom – the megawatt glare that screams into the gently lit room is not discreet. Not everybody else was bored at that moment.”

I often wonder, in fact, whether social media platforms and smartphones are the root cause of one very irksome aspect of life in the 21st century: the way people now endlessly chat during musical performances, seemingly unaware that if they concentrated silently on what was happening onstage, they might have a much better time.

And what is it people are being distracted by, whether they are alone, or in company? Social media comes down to an endless series of competitions, with prizes in the form of attention: likes, friends, comments. On top of that, Facebook has become humanity’s main means of reminding individuals of the exciting, fulfilling stuff that other people claim to be doing, and giving them the feeling they ought to join in. For all that Silicon Valley styles itself as being about liberating us from earthly concerns and creating a new kind of networked human, these things tap into aspects of our psychology that are primitive and animalistic.

In his brilliant polemic, 10 Arguments for Deleting Your Social Media Accounts Right Now, the virtual reality pioneer Jaron Lanier pithily describes what silently happens as we endlessly scroll: “Deep mechanisms in the social parts of our brains monitor our social standing, making us terrified to be left behind, like a runt sacrificed to predators on the savannah.”

I know when I last felt like that. It was when I was at school, and then university. I had a recurrently good time at both places, but I also vividly recall the sense of always either being in the crowd, or wondering why I wasn’t. In that sense, in the same way that the personal development of celebrities is sometimes said to be frozen at the point they first become famous, so Facebook and its effects were always going to be defined by its beginnings at Harvard. It has turned the world into one big college dorm, where there is rarely any silence, and anyone of a sensitive disposition longs for a bit of me time, to no avail. Among the many arguments against Zuckerberg’s goal of “bringing the world closer together”, perhaps, is the fact that the human condition demands that we also need to regularly be apart, and alone. Has that been forgotten in only 15 years?