I’m not sure I believe the model outlined in Robin Dunbar’s Grooming, Gossip, and the Evolution of Language. I’m not even sure about the specific details of Dunbar’s number. But, the overall insight, that the vast majority of human history has been defined by small groups with people you see again and again had an impact on our psychology seems robust.
The connotations of the very word “stranger” are complex but generally lean to the negative. And I think that makes sense. One of the tasks of cultural norms and values is to figure out a way that strangers can be interacted with in non-zero sum relationships.
All of this is to preface a banal assertion about interaction in day-to-day life if you are a middle-class professional. I get a lot of emails from people with common names, and it’s a non-trivial cognitive load to figure out if I should pay attention or not. Names like “David”, “John”, and “Omar” are so common that I’ve actually ignored people I shouldn’t because I didn’t realize it was that David or Omar. I’ve almost even responded to the wrong person when two people with the same first name are emailing me at the same time.
In a premodern village or a Paleolithic hunter-gatherer tribe, having a common name on a population-wide scale wasn’t a big deal. The people you would address by name regularly was far less than 100 over a year. But in today’s world, some people have to interface with ten different strangers per day, along with all the “regulars.”
If I was a parent considering names, this would be something that I would take into account. It’s probably not optimal to have a very rare name, because people might misspell it or misremember it, though it will be salient. But having a very common name can also be annoying, to the point where many people with common names now go by their middle name or a nickname. Rather, a familiar but not-so-common name is probably optimal.
To give an example, the name “Dennis” is not too common for people my age (as opposed to “David”). If I get an email from a “Dennis” there is only one or two people it could be.