Fact file: Why are languages so similar across Europe, yet so different in other continents?

It's a near-universal observation: European languages are largely similar to each other, yet no two types of Chinese are barely mutually intelligible. If we move the spotlight across the pond to South America, we can also see that the vast triangular land's wealth of languages - from Quechua on the broader west coast to Tupí-Guaraní in the south- bears strikingly little similarity to each other. But why?

Anthropological linguistics has a highly reasonable answer to this. We must first take geographical landscape into consideration. Europe (i.e., from west of the Ural mountains until the Atlantic ocean) is largely flat, with some more notable elevations in the south, making it easier for people of different areas to move around since ancient times. Not only that, but Europe is also spread from east to west, lying largely within the coordinates of 40 and 55 degrees north. This is also favourable from a climate point of view, since there was much less to adapt to for the many who chose to relocate within the continent.

Tightly knitted to this is also the matter of commerce. Thanks to the relatively flat land surface and the largely unchanging climate, Europeans have been actively trading with one another since ancient times. With increased trade came the need for communication, and with that came the desire to develop similar lexicon and linguistic structures. Exceptions can be seen, for instance, in Spain's Basque language, where natural boundaries have resulted in the language bearing almost no similarity to its surrounding Romance languages.

On the other hand, the same conditions do not apply to South America and China. South America, oriented more from north to south, consists of the most diverse range of climates imaginable. The unrealistic prospect of moving across climates implied difficulties for linguistic similarity to develop across the continent. In a similar vein, China's extremely diverse geographical landscape - with towering mountains and grand rivers here and there, it was not practical for people to cross boundaries and share their languages with neighbouring regions.

The relevance between typological similarity (distance) and environment is a testament to the idea that the diverse areas of linguistics, at their very core, can only be meaningfully studied in the context of how humans live.

This is part of The Applied Linguist's 'Fact File' column.