In 1990s Robin Dunbar, a British anthropologist, developed a controversial theory about the upper reaches of the human brain for social groupings. After studying hunter-gatherer tribes, rural townships, and other primates, he concluded that the human brain is capable of maintaining a maximum (on average) of 150 close relationships. This became known as Dunbar's Number, and it has since been scrutinized, corroborated, and criticized. However, it remains an important concept to the modern human as we navigate some very new social constructs.
Dunbar's theory began merely as an empirical finding. He noticed that different primates seemed to band together in set group numbers due to the high demand on each member to maintain social interactions (aka 'grooming behavior') with the other members. Dunbar created a formula to describe his findings, connecting band size to neocortex size. After applying this formula to the human brain he came up with 150. Next, he went to the historic records and found 150 again and again in connection with hunter-gatherer groups, Roman legions, and neolithic farming communities.
Today, we see Dunbar's number show up in academic sub-fields, corporate working groups, and many other surprising places. For example, the most successful members of social media platforms like LinkedIn have around 150 close connections; military companies are around 150 soldiers; many large corporations separate their departments once they reach 150 employees due to decreased efficiency at larger sizes. Sure, there may be some confirmation bias inherent to this magical number, but we must admit that it holds true in too many places to be merely random.
While Dunbar's Number describes the upper limit of our brains, it does not mention the ideal number of relationships. In our modern world, family and social groups have become more dispersed so that the number of close human relationships has actually gone down, not up, as you might have suspected. Social media platforms, email, and phones do create a larger web of connections, but at the expense of depth. And often there are negative ramifications. In my life I have chosen to not engage heavily (or at all) in most social media. I reach out to people most often by calling them. I am probably still under 150 close relationships, but, as a more introverted person, that suits me well. I get to spend more quality time with a fewer number of people.
When navigating the turbulent waters that is the modern social landscape, it is important to remember that evolutionarily we are wired to have fewer, more meaningful, face-to-face connections rather than an army of so-called virtual 'friends'. After all, when we look back on our lives we won't measure it by the number of Instagram followers that we had. We will think of all of the personal memories that we had with our dearest friends and family. That is worth more than gold.