The Evolution of Social Connection as a Basic Human Need
Reviewed By Rose Perry, Ph.D.
Humans have evolved the basic need for social connection because it is vital to our survival. This need is rooted deep within us biologically. And we have even developed an evolutionary warning signal that tells us when our need for connection is not met.
We all know that humans are social creatures. But our drive to connect with other people and form relationships is not just a whimsical motivation or casual coincidence. Social connection is a basic human need that is essential to our overall health and wellbeing [1-4]. It is as important as food, water, and shelter when it comes to laying the foundation for our ability to thrive and survive.
Our need for social connection is rooted deep within us biologically—not just as individuals, but as a species. In fact, as an astonishing amount of theory and research now suggests, humans have evolved the need for social connection.
Humans have survived for thousands of years through our ability to connect, communicate, and cooperate with each other. Looking around today, the advantages of forming social connections and working together in groups are readily apparent. Human cooperation and collaboration has resulted in complex social, cultural, and technological innovations, from the Internet to modern medicine. But why did humans and our hominid ancestors first come together to form socially connected groups?
Social connections provided many clear advantages for survival. Put simply, there was strength and safety in numbers. Banding together in groups allowed our ancestors to hunt larger animals that would be difficult for any one individual to do on their own. Working together to fend off predators and protect each other further increased the odds of survival. Being connected in groups permitted the growth of the extended family to help one another parent and raise children, promoting survival. These behaviors conferred such benefits that evolution naturally selected for more social connection over time [5].
But beyond behavior, there were also biological changes. Some of the strongest evidence for the idea that the need for social connection has evolved in humans is the fact that humans have unusually large brains. Across animals, brain size is highly correlated with body size. Large animals like whales have large brains whereas small animals like mice have small brains. But humans have incredibly large brains relative to our body size.
So why are our brains so big? In the 1990s, the anthropologist Robin Dunbar claimed that the reason why humans developed such large brains (in particular the neocortex, or outermost part of the brain) was so that we could deal with the growth and complexity of social interactions and social networks [6]. He showed that a species’ group size was the strongest predictor of an animal’s neocortex size. The bigger the group, the bigger the brain. Because navigating numerous social interactions, relationships, and networks was so cognitively demanding—but also rewarding—we had to develop bigger brains to accommodate it. Basically, we evolved big brains in order to connect.
More recently, neuroscientists have used functional magnetic resonance imaging, or fMRI, to better understand how our brain functions to support us socially. Researchers have found that there are two distinct brain networks that underlie social and non-social thinking. The respective brain network is activated depending on whether we are engaged in a social or non-social task. But what’s most interesting is what the brain does when we’re not engaged in anything. Evidently, when we finish doing something non-social, our social brain network turns back on almost instantly, like a reflex [2]. Our brain’s default mode is social.
Why is this? As neuroscientist Matthew Lieberman says, “Evolution has placed a bet that the best thing for our brain to do in any spare moment is to get ready to see the world socially.” We are always preparing for our next social interaction, to engage with the thoughts, feelings, and intentions of other people.
So, if our brains have evolved to fulfill the basic need for social connection, what happens when we are socially disconnected? It turns out there is an evolutionary adaptation at work here too.
Our need for social connection is so important that we have evolved a signaling mechanism that lets us know when we need more of it. Loneliness is a vital warning signal that tells us that our basic human need for social connection is not met [7]. Just like hunger and thirst are signals that we need food and water, loneliness signals that we need connection. And this signal is rooted deep within our brain.
In support of this idea, a group of researchers used fMRI to examine the brain activity of people who had undergone 10 hours of social isolation and 10 hours of fasting from food on separate days [8]. They found that following isolation, people displayed increased midbrain activity when shown pictures of some of their favorite social activities. This brain activity was also related to subjective ratings of social craving and loneliness. Likewise, after fasting, people also showed increased midbrain activity when shown pictures of their favorite foods. And this activity was also associated with their self-ratings of food craving. Taken together, these results suggest that social isolation triggered a “craving” response to social cues that was similar to food craving after fasting. In other words, people who experience social isolation or loneliness crave social connection like a hungry person craves food.
All this evidence clearly points to the idea that humans have evolved a basic need for social connection that is firmly grounded in our brains and bodies. So the next time you feel lonely, remember that this is your brain trying to tell you that you need social connection. And just like we don’t ignore the signs of hunger and thirst, we shouldn’t ignore the signs of loneliness.
In-text References
[1] Baumeister, R. F., & Leary, M. R. (1995). The need to belong: Desire for interpersonal attachments as a fundamental human motivation. Psychological Bulletin, 117, 497–529.
[2] Lieberman, Matthew D (2013). Social: Why our brains are wired to connect. Oxford University Press.
[3] Cacioppo, J. T., & Patrick, W. (2008). Loneliness: Human nature and the need for social connection. WW Norton & Company.
[4] Holt-Lunstad J. (2022). Social connection as a public health issue: The evidence and a systemic framework for prioritizing the "social" in social determinants of health. Annual review of public health, 43, 193–213. https://doi.org/10.1146/annurev-publhealth-052020-110732
[5] Von Hippel, W. (2018). The social leap: The new evolutionary science of who we are, where we come from, and what makes us happy. New York: Harper Wave.
[6] Dunbar, R. I. (1998). The social brain hypothesis. Evolutionary Anthropology: Issues, News, and Reviews: Issues, News, and Reviews, 6(5), 178-190.
[7] Cacioppo, John & Hawkley, Louise & Ernst, John & Burleson, Mary & Berntson, Gary & Nouriani, Bita & Spiegel, David. (2006). Loneliness within a nomological net: An evolutionary perspective. Journal of Research in Personality, 40, 1054-1085. Journal of Research in Personality. 40. 1054-1085. 10.1016/j.jrp.2005.11.007.
[8] Tomova, L., Wang, K. L., Thompson, T., Matthews, G. A., Takahashi, A., Tye, K. M., & Saxe, R. (2020). Acute social isolation evokes midbrain craving responses similar to hunger. Nature Neuroscience, 23(12), 1597–1605. doi:10.1038/s41593-020-00742-z