1 Homo Socialis No enjoyment equals the satisfaction we receive from the company of those we love and esteem; as the greatest of all punishments is to be oblig''d to pass our lives with those we hate or contemn. --David Hume, A Treatise of Human Nature In February 2022, a life-threatening storm sent police in Prestino, Italy, to check on Marinella Beretta''s "small home in the midst of myriad other houses." Marinella was home, but the police were too late. Her withered skeleton was sitting at the kitchen table. Some other risk had taken her life more than two years earlier. Marinella died not only completely alone but also completely unnoticed since her neighbors last reported seeing her in September 2019. No family had come or called to check on her. No friends emailed to find out why she didn''t show up for some event or another.

Marinella had lived so independently that nobody noticed her absence anywhere, in any capacity, for more than two years. "The mystery of Marinella''s invisible life behind the closed gate of her cottage teaches us a terrible lesson," reported the Italian newspaper Il messaggero. "The true sadness isn''t that others didn''t notice her death. It''s that they didn''t realize that Marinella Beretta was alive." It''s hard to imagine that someone could die so completely alone in today''s world, but it''s nearly impossible to imagine it happening at almost any previous point in human history. Daily life for our ancestors was, by necessity, deeply social. People lived most moments of their entire lives surrounded by family and neighbors, whether they wanted to or not. Simply staying alive required routine interaction, bound together not by impersonal exchanges of money but by the social threads of reciprocity.

You scratch my back and I''ll scratch yours; an eye for an eye, a tooth for a tooth. Life wasn''t easy, but you didn''t die unnoticed at your kitchen table. Times have changed. Thanks to countless technological advances, we are now more independent, and spending more time by ourselves, than ever before. The number of people living alone in the United States, for instance, has more than tripled over the last century, from 7.7 percent in 1940 to 27.7 percent in 2020. In many parts of the world, you could wake up alone in your home on any given day, eat breakfast bought online and delivered touch-free to your doorstep, entertain yourself by surfing the internet or watching television, go wherever you want in your car or on public transportation, and pay for whatever you need with a credit card, all without ever having to actually talk to another human being.

No back-scratching required. The benefits of independence are instantly obvious: You can live where you want, do what you want, and avoid almost any interaction you don''t want. The cost of independence is that we can now choose to live our lives feeling more isolated and alone than was likely at any point in human history. According to the British historian Fay Bound Alberti, descriptions of loneliness as we think of it today didn''t show up in English-language books until the early 1800s but have been skyrocketing ever since. Even the meaning of loneliness seems to have evolved over time. Before 1800, Alberti finds, the rarely used terms "lonely" and "loneliness" were generally used to describe the physical state of being alone rather than the psychological state of feeling disconnected. Although it''s possible that English speakers before 1800 were somehow unable to feel lonely, that seems preposterously unlikely to me. More likely is that it was such a rare experience that people didn''t write about it.

Not so today. Loneliness is now such a popular concept that dictionaries provide not just one definition but two, including both the traditional meaning that psychologists refer to as social isolation and the more modern psychological state of feeling disconnected. In 2023, the U.S. surgeon general declared loneliness an epidemic. Roughly 45 percent of Americans in 2018 reported experiencing some degree of loneliness on a regular basis, and 58 percent reported feeling that they always or sometimes feel as if nobody knows them well. This was even before the COVID-19 pandemic forced many into isolation, an event that seemed to impact loneliness among younger Americans the most. A survey of nearly twenty-five hundred Americans conducted late in 2021 found that 79 percent of people aged eighteen to twenty-four reported feeling lonely to some extent compared with only 41 percent of seniors aged sixty-six and older, a flip in the typical demographic patterns of older people being lonelier observed before the pandemic.

One study comparing scores on the gold standard used by psychologists--the UCLA Loneliness Scale--found a steady increase in loneliness among young adults since it was first used in 1974, an increase that is roughly comparable in statistical terms to having the height of the average person increase by three inches over the last four decades. Whether you''d call an increase of three inches over that time period a tallness epidemic might be open to debate, but you''d definitely notice that "kids these days" were towering over their parents. Your Stone Age brain wasn''t built for this. It''s impossible to understand the full cost of making mistakes in our social lives without understanding how deeply sociality is woven into the fabric of our being. From serving as a basic need on par with eating and drinking to shaping our brain size to determining our self-esteem and sense of identity, social connection is the stitching that holds our lives, and our societies, together. We are Homo socialis. Social Needs That loneliness feels painful tells us something very basic about what we need to survive and thrive. Our bodies, after all, aren''t in the habit of sending us spam messages.

When we''re feeling good, that''s a signal that something is going well and maybe should be done more often. When we''re feeling terrible, that''s a signal that something is wrong and probably needs to be changed. The reason drinking a tall glass of water when you''re thirsty feels great is the same reason a big hug from a good friend when you''re sad feels great: It''s your brain''s reward system telling you that this is a good thing. This is why the opposite of loneliness feels like happiness. The reason our brains are built to work this way is fairly obvious. For most of human history, being alone or ostracized for any meaningful length of time was essentially a death sentence. Those capable of maintaining strong social connections were likely to both live longer and pass on these cooperative traits by having more children. Even Darwin recognized the evolutionary value of prosociality, noting that "selfish and contentious people will not cohere, and without coherence nothing can be effected.

" Indeed, survey results indicate that people who are consistently selfish even today also make less money and have fewer children. Put simply, a human brain that makes social connection a top priority survives longer and succeeds better than one that does not. For much of the twentieth century, though, psychologists failed to recognize social connection as a basic human need, treating it instead as a luxury good or as sentimental baggage that distracted us from really important needs like eating and sex. Abraham Maslow, a psychologist best known for his theory that motivation operates on a "hierarchy of needs," designated belonging as a mid-level need in his hierarchy that we cared about only after we felt safe and well fed, relegating it to bronze-level status in motivation''s Olympics. Behaviorists in the early twentieth century went even further, speculating that children cry for their mothers not because they need social connection but because they need something else, like food or warmth. They even speculated that a perfect child could be raised alone in a box as long as it was kept comfortable and well fed, without ever requiring human contact. Nonsense. These theories were disproven by scientists the moment they were actually tested.

The opening sentence of one review paper from 1976--just over thirty years after Maslow published his theory--describes the situation as an "interesting paradox": "The theory is widely accepted, but there is little research evidence to support it." The authors later clarify that by "little research evidence" they really meant "no evidence." Although Maslow was right to note that our needs go far beyond the basics of sex and sustenance, we don''t seem to pursue them in the ordered or hierarchical fashion he suggests, but rather pursue a small set of fundamental needs on an as-required basis. There''s no better illustration of the simultaneous pursuit of basic needs than the image below of a young rhesus macaque acrobatically clinging to its soft and warm "cloth mother" while feeding from the cold steel of its "wire mother." This image comes from Harry Harlow''s famous research on the importance of love. Harlow found that young rhesus monkeys raised with a "wire mother" that provided food, but no physical sense of love or connection, didn''t grow up to live happily ever after but rather withered away and died young. You can hear Harlow''s contempt for the psychological theories of the time in his summary of his own work: "It takes more than a baby and a box to make a normal monkey." It certainly takes more than a baby and a box to raise a normal human being, as Harlow''s contemporary John Bowlby observed.

His study of perfectly well-fed orphans who were nevertheless wasting away in cribs untouched and alone during World War II found that many were "gravely damaged for life." Our social needs don''t end after i.