There's a lot of research on this, particularly from Robin Dunbar, who gave us "Dunbar's Number" https://en.wikipedia.org/wiki/Dunbar%27s_number https://en.wiki

There's a lot of research on this, particularly from Robin Dunbar, who gave us "Dunbar's Number" https://en.wikipedia.org/wiki/Dunbar%27s_number https://en.wikipedia.org/wiki/Dunbar%27s_number