Having friends has dramatic effects on our happiness, mental well-being and longevity.

There is a limit to the number of friends we can manage at any one time, sometimes known as ‘Dunbar’s number’.

This limit is imposed by a combination of the time and the cognitive demands (the latter a function of prefrontal cortex volume) of maintaining relationships.

There are striking gender differences in how relationships are maintained.

The Internet has not (yet) changed any of this.

Read more:

Dunbar, R. I. M. (2018). The Anatomy of Friendship. Trends in Cognitive Sciences, 22(1): 32-51. https://doi.org/10.1016/j.tics.2017.10.004.