By now you’ve probably heard that your relationships are key to a long, happy life. Research keeps confirming their importance over and over again.
But why is that? What is it about our relationships that make them so central to our lives?
According to neuroscientist Ben Rein’s new book, Why Brains Need Friends, it comes down to our brains. As he explains in the book, that grey matter in our heads is exquisitely optimized for social connection, and our relationships keep our brains (and, therefore, ourselves) healthy and happy.
“The human brain has been shaped through evolution to reward us for connection and punish us for isolation,” he writes. “As such, we have so much to gain from socializing, and arguably even more to lose without it.”
How our brains respond to socializing
Our brains tend to release three neurochemicals in response to socializing, all of which play a role in making us want to connect, writes Rein: oxytocin, serotonin, and dopamine. Oxytocin earns the moniker of the “love” or “tend and befriend” hormone because of how it stimulates the reward center of our brain when we’re with loved ones, which helps us feel good.
Oxytocin offers more than a warm glow feeling, though—it also has positive health effects. Oxytocin has been found to reduce stress, anxiety, and inflammation, and to be neuro-protective and support healing from wounds, writes Rein. This may explain why people in loving relationships (who display high levels of oxytocin) tend to live longer, he says.
“Thanks to the restorative nature of oxytocin, love may offer systemic benefits for our health and well-being,” he writes.
Oxytocin also triggers the release of the other two chemicals, which have their own benefits. Serotonin augments the good feelings you get from social encounters, while dopamine (implicated in learning) motivates you to want “more of the same”—which in this case means more social contact. While dopamine can also lead to addiction (making people crave the feel-good drugs, for example), its release during pleasurable social encounters helps us to want to seek out more socializing.
These neurochemicals can play different roles in different situations. For example, they help parents bond with their children, make (along with endorphins) falling in love and having sex desirable, and inspire friends to deepen their intimacy. This reinforcing system has evolutionary roots, says Rein, because it’s linked to safety and reproduction—our two strongest biological drives.
“Our brains are built so that social connection feels good and is inherently reinforcing. This keeps us together—and therefore keeps us alive,” he writes. “This is what it means to be ‘wired for connection.’”
Empathy and mimicry
Rein goes on to explain other ways our brains assist us in socializing. One is through emotional contagion, an element of empathy that can attune us to another person’s feelings. We are built to resonate with others’ feelings, he writes, which helps us to better understand them, feel in synch with them, and care about them.
Emotions don’t just jump from one person to another, though. Instead, we unconsciously mimic each other’s facial expressions when we’re with them, grimacing or smiling when they do, for example. This can trigger a milder version of the same feeling in ourselves, as our brain interprets our facial muscles. In this way, you’ll feel a bit happier when someone smiles or cringe if you see someone else cringe.
“Our bodies are stocked with powerful and sneaky systems that guide our emotions beneath our awareness,” write Rein. “The muscles in your face do more than help you express emotions. The also help you understand and take on others’ emotions.”
That explains why facial expressions are so important for interpersonal understanding—and one reason why texting or emailing someone can sometimes lead to gross miscommunication. Using Botox, which can affect muscle contraction in the face, is also problematic, as that can affect a person’s ability to use facial mimicry, interfering with their ability to feel someone else’s feelings and empathize.
While empathy often develops naturally over time, sometimes people’s brain chemistry or negative experiences will hamper that process, says Rein. Fortunately, though, he adds, we can become more empathic through certain practices, like meditation or compassion training. This is something Rein advocates for, suggesting that the potential costs of caring for one another (i.e., through feeling their pain) are far outweighed by our need for social closeness.
“When you take on someone else’s pain, you become more motivated to step in and help them, because you feel bad,” he writes. “Sure, empathy can hurt, but what would we be without it?”
Brains can also interfere with connection
While we may be built for social connection, that doesn’t mean we always seek it, though. As Rein notes, we live in a world that sometimes makes social connection more difficult, whether that’s due to our over-reliance on technology, changing expectations for family and community life, or pandemics that keep us isolated from one another.
(Avery, 2025 256 pages)
And that’s a problem when it comes to our brains. Not only were we built to read facial expressions and feel another’s feelings, we also get emotional information from vocal tone, touch, and body language. To enhance communication and understanding by making the most of our brain’s strengths, says Rein, we need in-person interactions, which are superior to video-chatting, phoning, or texting for making relationships work.
“After experiencing less ‘lifelike’ interactions (like texts or phone calls), people tend to feel lonelier, sadder, less affectionate, less supported, and less happy than after interacting in person,” he writes.
Yet even if we eliminated outside interferences with getting together, we may still avoid in-person encounters. Why? Because of some of the less helpful ways our brains direct us.
While we need to socialize, we also have a biological need for safety. That means our amygdala (the part of our brain that alerts us to danger) can be active (a little or a lot) when we encounter uncertain situations, including social ones. Our amygdala is alert to potential threats, keeping us from feeling comfortable around people who aren’t predictable (who aren’t, for example, part of our “tribe”). Similarly, we don’t have as much emotional resonance for strangers as we do for people we know well, which can mean selectively caring more about people who are similar to us.
Our pre-frontal cortex can play a role in reducing social connection, too, because of how it tries to predict the future based on messaging from other sources and our own past experiences. If our brain tells us it’s dangerous or may not work out to interact with other people, we’re bound to isolate ourselves more than we should.
“In many social situations, the brain does a frankly shitty job. It makes bad predictions and suffers errors of calculation that can deprive us of necessary connection,” he writes.
Rein recounts the many research studies showing how bad we are at predicting the outcomes of socializing. We tend to underestimate how much we’ll enjoy a conversation and overestimate how likely we’ll be rejected by someone else. We also tend to misjudge the positive effects of a compliment or expressing gratitude, which, if we used them, could help endear us to others and vice versa. By going over these studies, Rein hopes to encourage us to go beyond our fears or assumptions and engage in conversing more than we think we should—even those of us who are introverts.
“Your unique combination of nature and nurture may determine how much pleasure your brain experiences from being around others; but at the end of the day, everybody needs social connection,” he writes.
And therein lies Rein’s main theme: We need to understand what gets in the way of having a more socially focused life and find ways to overcome it. That may mean picking up the phone when we’re reluctant, saying hello to our neighbors when we’re shy, or participating in community events even if we’re a little nervous about being around strangers. Rein hopes that by helping people recognize their brain’s limitations, as well as its strengths, more of us will prioritize social interaction in our daily lives—not just with friends, but with our larger communities—and create a more socially supportive world.
“Division is the enemy of brain health,” he writes. “To construct a society in which we truly choose and prioritize connection, I believe we must identify these barriers and address them head on.”
Our brains are counting on us to do so.