The first time your baby laughs at something you didn't do on purpose

For a long time you are the entertainment.

You make faces. You do voices. You repeat the one thing that got a reaction on Tuesday until it stops working. Most of it earns a polite response — the social smile, which babies are extremely good at and which is not quite the same thing.

And then one day something entirely unrelated to you happens, and your child laughs properly. From somewhere lower down. Without warning.

It's never what you'd expect

It's a door closing. A sneeze. A dog barking two gardens away. Someone dropping a spoon. The sound of the kettle. A sibling falling over — which is, apparently, the funniest thing that has ever happened in the history of the world.

What all of these have in common is that nobody was performing. The comedy was accidental, which means it was theirs — they found it, unassisted.

"Four months of peekaboo. First real laugh was the toaster."

Why it's a bigger moment than it looks

A laugh at a joke you told is a response to you. A laugh at a spoon hitting the floor is something else: it's a small, early piece of evidence that your child has an opinion about the world that you did not put there.

That's the first sighting of taste. It arrives well before language, and it does not go away — the child who found the toaster funny at seven months turns out, quite often, to be the one who finds odd things funny at seven years.

It also marks the moment you stop being the whole environment and start being one of the things in it.

Worth having on record

Nobody films this, because by definition nobody knew it was coming.

• What caused it — as specifically as you can, including where you all were
• Whether it worked a second time (usually not, which is part of the story)
• What the laugh sounded like before it became a proper laugh
• What they found funny for the whole following month

That last one is the most revealing, and the shortest-lived. Babies have distinct comedy eras. A month of falling-over. A month of the word "no". A month where hiding one's own face is unbeatable material.

The part that fades

You will remember that your child laughed. You will not remember, in three years, the exact sound of it at eight months — the wheezy, slightly alarming early version that isn't quite a laugh yet.

One line and, if you can manage it, four seconds of audio. Of everything in the first year, this is the one that ages best, and the one almost nobody thinks to keep.