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New frontiers in evolutionary linguistics

Our mother tongues seem to us like the natural way to communicate, but it is perhaps a universal human experience to be confronted and confused by a very different language. We can’t help but wonder how and why other languages sound so strange to us, and can be so difficult to learn as adults. This is an even bigger surprise when we consider that all languages come from a common source. That is, languages weren’t created differently, but became different as their speakers spread out across the world and lost touch over millennia. So the real question is, what caused them to become so different? Are there limits on how different they can become?

Linguists have been trying to answer this question for a long time, and we now know of many basic principles of language change – some changes to sounds are predictable, because they make words easier to say. Some changes to grammar are predictable because they make speech easier for our brains to process. Some changes reflect differences in the kinds of conversational topics that matter to different groups of speakers.

So, just like biological species adapt to survive, the languages we speak change and adapt to suit our physical articulators, our brains, and the things we want to talk about. Our role as scholars of language evolution will be to study these processes, and explain what constrains the variety in languages we can hear today – all the way from genetic constraints on our physical and cognitive abilities (biological evolution) to the way words and grammatical constructions compete for survival (cultural evolution).

One such constraint that has been proposed is the climate. At first, this seems like an odd idea. Besides some exaggerated claims that some languages have many different words for snow, could the way we speak really be affected by the weather? But from another perspective it makes sense. Speaking is a physical act – we flap folds of skin around in order to create sound waves that propagate through the air. The way this happens depends on the humidity and temperature of the air, and anyone who has been outside in very cold or dry conditions, or tried to sing with a dry throat, knows that your voice is affected by these properties, too. We also know from studies of animal communication that croaks, chirps and hoots are specially adapted to be heard in the particular ecology of the critters producing them.

Therefore we propose that if some sounds are harder to produce in certain climates, even by a little, then over a very long time, languages will adapt to avoid using them. For instance, we know from physiological experiments that controlling the pitch of your voice becomes harder in dry conditions. So we should be able to observe patterns of differences between languages in dry places and languages in humid places.

This is a tough idea to test, but in the last decade, for the first time, we can now look at the similarities and differences in thousands of languages – and thousands of locations around the world – using computational tools to help us. You can take a look at these patterns yourself on websites like the World Atlas of Language Structures or the World Phonotactics Database. In recent research, we looked at these databases, and found that the use of pitch to distinguish words – so called ‘lexical tone’ as exhibited by e.g. Mandarin Chinese – is rarely found in dry places.

However, it’s a tricky process to disentangle the effects of climate from the already established factors of language change, from historical contact between languages, and from chance events. Indeed, many critics have assembled to point out just how difficult our story is to support. Experts in lexical tone provide case studies to show that it is a much more complex phenomenon than we have assumed. Experts in phonetics have dug into the physics of speech to question how big the effect really is. Experts in statistics pointed to flaws in our original analyses. Historical linguists built models of the spread of tone over centuries to demonstrate how the patterns might just have appeared through being borrowed from neighbour to neighbour.

It’s clear that research on this link has a long way to go before it’s watertight, but we are greatly encouraged by the responses of our critics. While many dialogs in Evolutionary Linguistics can get bogged down in arguments about theoretical distinctions or differences of opinion, it is refreshing that new debates are engaging with the data, even if they are mostly skeptical. Science is all about addressing and refining questions with data, and the store of questions to ask – and ways to answer them – shows no sign of drying up.

Featured image credit: Woman-close-up-portrait-face-cold, by skeeze. CC0 Public Domain via Pixabay.

Recent Comments

  1. Andrew Carlrission

    My son also speaks Piraha and he claims the tribe speaks to Everet without recursion because he acts like a child and they don’t want to confuse him.

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