Here on Earth, we speak over 7,000 living languages. But in science fiction, alien species routinely turn out to have just one language, or a few major dialects at best. Over at Slate, they ask whether this is realistic — or whether we're just lumping alien languages together, based on shared characteristics.
The Slate article considers a few explanations for alien linguistic monocultures, including Noam Chomsky's theory that all Earth languages come from the same source, and another theory that languages are best grouped together by their surface features. But writer D.S. Bigham doesn't consider another possibility — that maybe a society that learns to travel to other star systems will evolve towards a single language to make communication among its far-flung members more feasible. [Slate]