Recently, I received an e-mail. Andrea and Noah are very happy to welcome little Ethan. He was born on November 12, is 52 cm tall and weighs 3300 g.

I never understood why parents always announce the height and weight of their new-born baby. Maybe it is because, even though that new little person takes up each of the many (many!) waking moments of their lives, they actually don’t know all that much about them. So they stick to the basics: name, date of birth, height, weight, until they figure out who little Ethan really is.

Meanwhile, I have a different, yet related question: Who the hell are Andrea and Noah?

The names don’t ring a bell. Or rather: They ring too many bells. I know a couple of Andreas and a couple of Noahs. I don’t know a couple called Andrea and Noah. Except, apparently I do. There was an Andrea I went to uni with and her boyfriend might have been called Noah. Or he might not. Also, this was ten years ago. And it might be a different Andrea. Sometimes I think there are too many of them. Not Andreas specifically, but people.

You know how, if you read a Dickens novel, the same characters show up again and again? Your childhood classmate helps you confront your childhood bully, while your childhood friend seduces your childhood sweetheart, and so on. I always thought this was a plot device. But really, maybe there weren’t that many people around if you moved in a particular circle in 19th century London.

But nowadays? Especially in my line of work, people move all the time. We do our undergraduate studies in one place and our PhDs in another, and then we move again to do a postdoc (or three) and then we move again for an industry post or faculty position or whatever it is we do.

And in each of these places, we meet people, we connect, we bond. We have classmates and coworkers and roommates and people we meet at parties and people on our soccer teams and collaborators and people we teach and people who teach us.

People often say it’s a small world, mainly because occasionally, you will run into someone you know. Or into someone who knows someone you know. Or into someone who comes from where you come from. Or into someone who has been there. Or someone who knows someone who has been there (“And what are the odds?!“)

But the world is huge. Wherever you go, you meet new people. People you haven’t met before. Even if we count not just acquaintances, but only people who, at some point, have touched our lives in a meaningful way … there are just so many of them.

When I think about it, it makes me dizzy. This might be because we have evolved to live in small-ish social tribes. Dunbar’s number (after Oxford anthropologist Robin Dunbar) is an estimate of the number of people a person can have a meaningful connection with. It is about 150. The size of a reasonable tribe. About the number of facebook friends most of us have. About twice the number of named characters in David Copperfield (but if you count villagers, sailors, passers-by and so on, 150 is probably about right).

I am way beyond Dunbar’s number. I know too many people. To the extent that I am not sure I know them any more. Which brings me back to the question: Who are Andrea and Noah?

I tried googling Noah’s full name. No chance. He is, as they say in Swedish, ogooglebar.

I would google for Andrea from college, but I don’t remember her last name. Also, the more I think of it, maybe she wasn’t really called Andrea.

I asked my boyfriend:
– Hey, do we know a couple called Andrea and Noah?
– No. Why?
– They just had a baby.
– ??

I looked at the picture they sent. A picture of Ethan alone, without parents. I can tell you one thing: Contrary to what the proud grandparents might say, little Ethan certainly does not look “exactly like” any of his relatives. At least not enough to provide a helpful clue. At least not to someone ho has no idea who his parents are, but might or might not know his mummy from college ten years ago.

OK, so I don’t know who they are. How should I respond to their e-mail? What is the protocol for baby congratulations in this massive post-Dunbarian social universe we live in?

Let me do it this way: Andrea, Noah: Congratulations. Even though I am not sure who you are, I am sure you deserve to be happy. My best wishes to both of you. And Ethan: Welcome to Planet Earth. Enjoy. It’s a big, big world.