Like most of us, photographer Tanja Hollander has a ton of friends on Facebook—626 to be exact. But while most of us take that for granted, the weirdness of having hundreds of “friends”— some of whom she’d never met, some that now live in faraway places—prompted Hollander to embark on an ambitious, life-changing project.

She decided to visit every single one of her 626 Facebook friends, go into their homes and take composed photos of them. All of this she did to find out just what our relationship is with those people that we call “friends” today.

“There were ex-lovers with new partners, ex-partners of good friends, art dealers, curators, people from high school I hadn’t seen in over 20 years,” Hollander said. “And I asked myself, ‘I communicate with them, but am I really friends with all of them?’”

The short answer is somewhere between “sort of yes” and “yes.” After millions of years of evolution—and hundreds of thousands of years of human evolution—our brains have become hardwired to love our inner tribes, and there is a numerical cap on how many people can fit into that inner circle.

But with the advent of the Internet, neurologists have seen our brains adapt quickly to the extended social networks made available to us online. This is thanks to the fact that our brains are so plastic and adaptable, but it’s in stark contradiction to the way social groups usually function.

It All Goes Back to Monkeys

In primate social groups, bonding happens through social grooming. In fact, it’s such an important part of group life that monkeys in the wild, for example the Capped Langur of India, have been observed to spend as much as 42% of their waking time grooming each other. That’s a significant chunk of the day.

Why do they do it? On one level, it helps the group maintain its relationships. On a more physical level, touch simply releases endorphins in the brain. Endorphins are our brain’s natural painkiller—they stop pain and make us feel good. This is why many creatures in the animal kingdom, not just primates, sleep together in dens. It actually feels better than sleeping alone.

The same is true for humans. Millions of years of evolution have made us want to be touched because being touched makes pain go away.

social grooming

“We underestimate how important touch is in the social world,” explains Robin Dunbar, a British anthropologist who studies how endorphins get released in the brain. We can communicate tremendous amounts with just a light brush on the shoulder, a pat, or a squeeze of the arm or hand. “Words are easy. But the way someone touches you, even casually, tells you more about what they’re thinking of you.”

Touch Releases Oxytocin, the “Trust Hormone”

Physical touch has also been shown to release a hormone in the brain called oxytocin—popularly dubbed the “cuddle hormone,” the “trust hormone” and even the “moral molecule”—because it appears to influence many of our best behaviors. Oxytocin is like a social glue that keeps groups together. The hormone is produced in the hypothalamus, a part of the brain located just above the brain stem that regulates social behavior, fatigue, sleep, and circadian rhythms, among other things.

Oxytocin intensifies feelings of love and social closeness. It plays a major role in pregnancy and mother-infant bonding, and a 2012 study published in the Journal of Neuroscience shows that oxytocin promotes bonding and monogamy in romantic relationships. Men with higher oxytocin levels tend to stand farther away from attractive women who aren’t their partner.

The hormone increases trust between people, which has big implications for how we’re able to function as a society. Trust resonates at the heart of our social and economic systems. It lubricates our business deals and enables us to engage in daily social transactions. But how does this hold up in the modern world, when it’s not realistic to spend 42% of our days on bonding like our monkey cousins do?

Social Grooming in the 21st Century

In his book Grooming, Gossip, and the Evolution of Language, British anthropologist Robin Dunbar proposes that humans might have evolved language as a sort of easy shorthand for social grooming. Without language, humans today would still be spending nearly half their time picking bugs out of each other’s hair, just like primates. Language allowed early humans to maintain social closeness without spending all their time on it.

The Internet adds another layer of abstraction to our social grooming practices. Thanks to social media, we’re now able to maintain our relationships with exponentially less effort. All we have to do is “like” each other’s status updates to say we care. Such behavior is definitely a kind of social grooming, but this deviation from how the rest of the animal kingdom does it is worth examining.

If we’re supposed to be getting our endorphins and oxytocin from touch, what happens when the majority of our social interactions go online? The Internet enables us to live individually, for the first time in history, without losing much else. Today it’s possible to live alongside 8.5 million people in New York City, but never have any physical contact at all.

In just the last 10 years of human existence, we’ve started to undo what animals have been doing for millennia. Internet communication circumvents the vital touch factor, potentially weakening our social bonds. Dunbar and his colleagues haven’t collected enough data to form an opinion yet, but they’re very interested in the impact of virtual social networks on overall social happiness and well-being.

Dunbar’s Number: Even Social Butterflies Have a Limit

In the early 1990s, Dunbar theorized that the size of a primate’s neocortex determines the size of its social group. The ratio of neocortex volume to brain size directly limits the amount of social relationships the brain is able to maintain. Most primates operate in groups of 50 or so.



This number can be extrapolated to accurately predict the social group size of any primate species—the bigger the neocortex, the bigger the tribe. The number of relationships the human brain can comfortably accommodate appears to be 150. This is called “Dunbar’s number.”

If you dig into ethnographic and historical archives, you’ll find 150 to be the sweet spot for hunter-gatherer societies throughout history:

  • Both the Bushmen of Southern Africa and Native American tribes typically have community sizes of about 150 people.
  • Neolithic farming villages, Hutterite and Amish settlements also cap out around 150.
  • Company size in professional armies, like in the Roman Empire, has also been remarkably close to 150.
  • Military batallions in 16th-century Spain also had about 150 soldiers each.
  • Even the 20th-century USSR divided its army into regiments of 150.
  • Perhaps the most surprising: the average number of academics in a discipline’s sub-specialization is around 150.

Inner circles fit into the larger whole

Your Dunbar number isn’t fixed. It exists on a sliding scale of concentric circles. Especially in modern society, where neighbors can move away and colleagues can change jobs—your closest 150 might be in constant flux.

The next inner circle is your group of closest 50 friends and family. These relationships tend to stay more constant. And the next most intimate number, according to Dunbar, is five. These are the five people you can always turn to in times of distress.

On the other end of the sliding scale, it’s increasingly possible to have more than 500 acquaintances. This number caps out around 1,500 because that’s how many individual faces your brain is able to facially recognize.

Dunbar notes that in the past, such groups have almost always been physically and geographically close. But that just isn’t the case anymore.

When You Have 1,500+ Facebook Friends

Chances are that you or someone you know is currently connected to more than 1,500 people on social media. Does this make the Dunbar number irrelevant? How many of your Facebook friends can you name from memory, without peeking at the list?

When researchers tried to determine whether social media networks like Facebook increase our number of meaningful relationships, they found that—at least for now—the essential 150 limit has remained constant. You might have 10k + followers on Twitter, but you’re not actually interacting with most of them.

“The interesting thing is that you can have 1,500 Facebook friends, but when you actually look at activity on sites, you see people maintain the same inner circle of around 150 that we observe in the real world,” Dunbar told the London-based Sunday Times.

Even for heavy social media users, the number of people on a friend list that you frequently interact with is remarkably small and stable. When you think about these numbers in comparison to the 7 billion people on the planet your brain isn’t able to compute—it starts to put humanity into perspective.

Wider Social Networks Linked to Increased Memory Capacity

For better or worse, online social networks are expanding the scope of human social groups. What our brains are doing to accomodate the data overload is actually quite astonishing and sophisticated. The human brain is incredibly plastic, and Dunbar told NPR that “there are some neurological mechanisms in place to help us cope with the ever-growing amount of social connections life seems to require.”

In a 2007 research study, Dunbar and his colleagues found that people with better long term memories are by extension able to remember more people. For example, organizing relationships into hierarchical groups—i.e. your ex’s extended family, or the people you met on your semester abroad in Thailand—allows the brain to cognitively manage more connections.

One thing Facebook does is allow you to passively keep track of peripheral social contacts who might otherwise drop out of your sphere. Basically, Facebook introduces a few extra people—or a few extra 100—to the outermost layer of acquaintances. It lets you communicate with people in a very low-cost way, effectively slowing the rate of decay in relationships where you no longer meet in person.

“It’s perfectly possible that the technology will increase your memory capacity,” Dunbar says. But as our virtual interactions become more dispersed and superficial, the expanding complexity of social group dynamics might be outstripping our ability to process.

Our Facebook Profiles Reflect Our Authentic Selves

Facebook in particular seems to flatten our complex social spheres into one homogenous ocean, in which we’re only capable of presenting a single identity. This is called context collapse, and, contrary to common belief, it makes it difficult to maintain constructed identities online.

Facebook is a context that shows the accumulated activities of our daily lives. Essentially, when you post to Facebook, you’re making all of your content visible to all of your contacts. This means you’re probably going to experience some “bleed through,” where people from random parts of your life see posts and pictures that weren’t intended for them.

According to Samuel Gosling, psychology professor at the University of Texas at Austin and author of Snoop: What Your Stuff Says About You, this just might not be a bad thing. Common belief would have it that even though we have a lot of friends, we’re fake online, right? Wrong! Research shows that we’re actually projecting our real selves on Facebook. People want to be themselves online because we feel more connected when we’re projecting our honest selves into the ether.

“It’s worth remembering that even in contexts where people might be able to create false impressions,” said Gosling, “there’s research showing that’s typically not what people want to do.” At the same time, confusing the boundaries can be a double-edged sword. We’ve all seen people spill their guts to Facebook. Why is it that people will confess things online that they’d never say to a room full of people?

The Pitfall of Losing Intimacy

The question is whether those of us who maintain superficial relationships with hundreds of people on social media do so to the detriment of our closest, most intimate relationships. Spending a lot of time building large networks of shallow connections might be replacing the meaningful and reliable relationships of more innocent years.

In his book, Bowling Alone, Robert Putnam argues that most Americans today have plenty of acquaintances. But we have increasingly fewer friends to whom we can discuss important matters or share our most authentic selves. In our high-speed culture of instant gratification, people forget that it takes time and effort to build true friendships.

Even those of us who spend a lot of time socializing IRL, or curating our online personas and raking in “likes,” are increasingly in danger of feeling disconnected from our friends in the moments we need them most. On the Internet, we might have far-flung networks of friends who we bond with over creative interests, work, dreams or anything. But in the physicality of our private homes, a lot of us are watching our Netflix movies alone.

Digital Tribes: The Dunbar Number Adapts to Online

Our real-world friends tend to know the same people we do because we inhabit each other’s physical “monkeyspheres.” But in deciding how to socialize online, we can approach it in more strategic ways. We can “groom” the contacts that we choose, leading to more effective professional networking, for example.

We live in a more mobile, fragmented social world, where Internet connectivy lets us stay connected with close friends over long distances via Skype and chat. This is also a world where we can make our best professional connections online.

Social media facilitates more effective collaborations. For example, your loose acquaintances online might help you generate creative ideas or find a job. What you get is the transfer of knowledge across boundaries like your current group of co-workers, your geographically limited friend group, and your local creative collaborators.

Even a weak connection between two people with shared interests can serve as a “crucial bridge” that brings together two close-knit groups of friends, according to sociologist Mark Granovetter. In other words, a casual acquaintance can link one group to another.

Tanja Hollander’s art

Artist Tanja Hollander, whose project to take portraits of all 626 of her Facebook friends—called “Are You Really My Friend?”—is scheduled to open at the Massachusetts Museum of Contemporary Art in March 2017. So far she’s traveled to 43 states, 5 countries, and roughly 150 towns or cities, averaging two weeks away from home per month. She reports feeling constantly touched by people’s hospitality and pride in showing their homes.

Amanda Hollander & Katy McCormack, Portland, Maine, 2011. Relationship: family, little sister. Years known: Amanda 30-35, Katy 0-5.

Early in her travels, Hollander was surprised when a professional contact, a designer in Houston, Texas, responded to her request about the photo project by inviting Hollander to stay in her home for the weekend. The fellow artist brought Hollander to a traditional Texas rodeo, and introduced Hollander to her parents and sisters.

Hollander was touched by how much personal time this woman took to share her “real life” with someone who was really just a long-distance professional acquaintance. For her to be willing to do that, “something must have existed between them” before Hollander arrived at her house.

The Disintegration of Digital Binarism

Hollander’s project served as a litmus test, or a “friend” filter. She reached out to Facebook friends about taking their portrait several times. If she got no response, she unfriended them, weeding out friendships that wouldn’t translate into real life.

People who were originally on the periphery of her Dunbar number—150—moved into more intimate circles after she’d spent a day in their homes. She’s formed a totally modern kind of tribe, based on the shared values and shared experience of making art. It’s the 21st century version of picking bugs out of each other’s hair.

It is entirely possible that, as we advance into the 21st century, the distinction between online and offline worlds may become increasingly less relevant. The notion of social media as a kind of “place,” divorced from physical reality, is an outmoded demarcation. It may be true that meeting a friend over Skype isn’t quite the same experience as meeting over coffee, but the channel Skype provides for friends to stay close throughout our crazy modern times is undeniable.

For individuals who embrace social media, and who share content and interact with network members, their online interactions are growing increasingly meaningful—we no longer separate out our online relationships from our physical interactions.

Facebook Use Triggers Oxytocin

Neuro-economist Paul J. Zak, a professor at Claremont College, is working to prove that social networking triggers the release of “feel good” hormone oxycontin in our brains. It’s the same feeling that we get from snuggling, and it builds trust and overall social wellness.

Accumulating research is beginning to show that interacting with our loved ones online releases the same hormones as seeing them in person, engendering trust and social happiness.

It turns out that social media users are a very trusting community. The more time you spend on them the more trusting you become.

A 2011 report from Pew Research found that “the typical Internet user is more than twice as likely as others to feel that people can be trusted,” with regular Facebook users the most trusting of all. “A Facebook user who uses the site multiple times per day is 43% more likely than other Internet users and more than three times as likely as non-Internet users to feel that most people can be trusted.”

The Real Monkeys: Teenagers on Instagram

Just like primates who spend half their days on social grooming, people who spend a significant chunk of their days on social media are engaging in important social bonding. We’re going to see more of this as the current youth generation enters adulthood

We haven’t seen an entire generation that’s grown up with things like Facebook go through adulthood yet, but it’s starting. In a recent episode of This American Life, Ira Glass spoke to two 13 year-old girls who are fabulously prolific on Instagram.

These teenage girls post selfies to the app, and they affirm each other with repetitive streams of positive comments, which might begin to seem mindless once you read more than 40 or so: “Gorgeous,” “Stunning,” “You’re so pretty.” These girls are getting a hit of oxytocin from every one of those comments.

This is an example of virtual social grooming, and to be honest, it isn’t much different from adult life on social media. For example, when you put yourself out there with a tweet you hope is clever, you’re really hoping someone in your social network will validate you with a re-tweet or a favorite.

What’s interesting about the 13 year-olds is that they seem to value virtual interactions as much as physical interactions. All of this makes you think about what friendship really is. In online interactions, there are real feelings going on, and your brain is really responding. As we move into an increasingly complex and nuanced social future, we’ll have to stay mindful about what our friendships mean to us.