One of the most unique features of the Basque language is its status as a language isolate. A language is considered to be an isolate when we are unable to find common features with other languages that tell us they are part of the same language family. For example, French and Spanish are distinct languages, but have similar sound systems and vocabularies. Thus, linguists are able to propose past sound changes and reconstruct a language that Spanish and French are descended from. With this connection, we say that they are part of the same language family (specifically, they are both Romance languages).
Image: The Indo-European Family Tree. This includes Spanish and French, but not Basque, which is an isolate and does not have a family.
Ethnologue, a linguistics website that focuses on cataloging the world’s languages, lists 82 existing isolate languages (1). This means that only 1.1% of the 7,000 languages that exist today are (believed to be) unrelated to any others. Language isolates can arise in a two ways: the language can be created and never split into daughter languages, but merely grow as one language; or the language can be part of a language family where the rest of the family has died away and there is no evidence it ever existed. This means it is often difficult or impossible to tell which circumstance the isolate has arisen from. Studying languages like Basque helps us to further our understanding of its history and come closer to knowing how it came to be a language isolate. Discovering connections between languages and uncovering language change is essential in understanding human language as a whole.