Why are there so many different languages in the world?

Right now, somewhere on Earth, someone is saying "hello" in a way you've never heard. There are about seven thousand languages humming across the planet — seven thousand different ways to ask for bread, name a star, or tell a joke. So why so many? Why didn't everyone just agree on one and call it a day? The answer is a slow, wonderful story about people drifting apart.
Start small. A language isn't a rulebook handed down from the sky — it's a habit a group of people share. They agree, without ever voting on it, that this sound means "dog" and that sound means "run." As long as everyone keeps talking to each other, the habit stays the same. Languages live inside groups, like a campfire that only stays lit while people keep tending it.
