Language, Darwin believed, was not a conscious invention but a phenomenon “slowly and unconsciously developed by many steps.” But what makes a language a language? In this short animation from TED Ed, linguist John McWhorter, author of the indispensable The Power of Babel: A Natural History of Language (public library), explores the fascinating world of fantasy constructed languages — known as conlangs — from Game of Thrones’ Dothraki to Avatar’s Na’vi to Star Trek’s Klingon to Lord of the Rings’ Elvish. Though fictional, these conlangs reveal a great deal about the fundamentals of real human communication and help us understand the essential components of a successful language — extensive vocabulary, consistent grammar rules but peppered with exceptions, and just the right amount of room for messiness and evolution.

We can see the difference between vocabulary alone and what makes a real language from a look at how Tolkien put together grand old Elvish, a conlang with several thousand words. After all, you can memorize 5,000 words of Russian and still be barely able to construct a sentence — a 4-year-old would talk rings around you. That’s because you have to know how to put the words together — that is, a real language has grammar; Elvish does. … Real languages also change over time — there’s no such thing as a language that’s the same today as it was 1,000 years ago: As people speak, they drift into new habits, shed old ones, make mistakes, and get creative. … Real languages are messy — that’s because they change, and change has a way of working against order. … Real languages are never perfectly logical — that’s why Tolkien made sure Elvish had plenty of exceptions.

Complement with this illustrated vintage guide to the science of language and the fascinating story of how Darwin shaped our understanding of why language exists.