New Evidence That We're Wired for Connection

A team at Harvard studying the social behavior of mice found that the brain treats isolation and loneliness in much the same way it processes hunger or thirst. Within the hypothalamus, the brain’s hub for all our basic needs, two groups of neurons influence how we respond during isolation vs. social interactions. Connecting with others, ten, is more than something to be desired; it is essential for our mental and physical well-being.

The Cost of Loneliness

Loneliness is far more than just an emotional burden. Prolonged isolation and sense of loneliness can contribute to a higher risk of depression, anxiety, heart disease, and even early death. Loneliness and isolation, though related, are not the same. Isolation is a consequence of being physically separated from others, which leads to fewer social relationships and less frequent social interactions. Loneliness, on the other hand, is the feeling of being disconnected even when surrounded by others. In the golden age of social media, millions still find themselves craving deeper, more meaningful interactions.

Social connection refers to not only being close to others but also feeling emotionally connected, cared for, and valued. Positive interactions with others reinforce the brain’s reward system. When we share a laugh with a friend or exchange a smile with a coworker, the brain releases “feel-good” chemicals. Serotonin brightens our mood, oxytocin fosters feelings of emotional closeness, and dopamine reinforces the idea that connecting with others feels good.

Loneliness and isolation can be both consequences and symptoms of several mental health disorders. After being isolated, even for a short period, the brain reacts in ways that can affect our mood and mental state. Reduced stimulation from social interactions leads to drops in “feel-good” chemicals and a rise in the release of cortisol, a hormone associated with stress. Over time, high levels of cortisol make individuals more sensitive to negative emotions that interfere with our intrinsic motivation for social interaction. The longer we isolate, the more our brain craves connection.

In the new study, led by Ding Liu, the research team observed how six families of mice responded to brief periods of isolation. These adult female siblings, initially raised together, were separated for at least five days. Once they were allowed to reunite, they eagerly interacted with each other. The team found that the longer the mice spent in isolation, the more time they spent interacting with each other upon reunion. However, mice that spent more than 4 weeks in isolation seem to start avoiding others almost as if they had become accustomed to being alone. This led investigators to ask: What if the desire for social interaction was not driven by wanting to feel good but avoiding feeling bad?

What Drives the Need for Social Connection?

Our most basic needs for food and water are often driven by a deep desire to avoid feeling uncomfortable. When you are hungry, your body signals discomfort through stomach pains or irritability to push you to find food. When you are thirsty, dry mouth and dehydration prompt you to grab a drink of water. The same principle applies to social connection. Our brain is wired to crave interaction, not just because it feels good but because feeling isolated or lonely is uncomfortable.

Located at the base of the brain, the hypothalamus serves as the brain’s hub for regulating our basic needs, helping to maintain balance in our body. In addition to hunger and thirst, the hypothalamus also activates when body temperature changes or your body needs to sleep. It controls the release of various hormones that communicate what the body needs and influence how we respond. By mediating the release of oxytocin and cortisol, the hypothalamus has considerable control over how we interact with others.

According to this new study, two distinct groups of neurons in the hypothalamus regulate social behavior. The team used a technique called calcium imaging, which allows you to observe how neurons work in real time. As the mice freely interacted with their environment during both the isolation and reunion periods, a miniature microscope and fluorescent dye tracked changes in brain activity. What they found was that specialized neurons in the hypothalamus activate during social isolation but promptly stop firing once the animals are able to interact again. Another group of hypothalamic neurons appear to fire only during reunion and not isolation.

These two groups of neurons seem to encode different states of social behavior – one representing the brain’s urge to seek connection when isolated, and the other signaling the brain’s response to having that need met during social interaction. The team found that physical touch activates “social satiety” neurons. A mouse interacting with another prompts these specialized neurons to release dopamine and inhibit the activity of connection-seeking neurons. Similar to how eating reduces hunger, social interaction reduces loneliness.

Conclusion

Although social media has enabled the world to connect like never before, many of us still find ourselves feeling disconnected. This paradox begs the question: What does it truly mean to feel connected? This study reveals that physical interaction may be the key to restoring social connection. Beyond a screen, small, tangible experiences like a hug or handshake engage the brain’s reward system and may offer a deeper sense of fulfillment that digital communication alone cannot provide. Social connection is as essential to survival as food, water, and shelter, and we should start prioritizing it as such.