Languages are extremely diverse, but they are not arbitrary. Behind the bewildering, contradictory ways in which different tongues conceptualise the world, we can sometimes discern order. Linguists have traditionally assumed that this reflects the hardwired linguistic aptitude of the human brain. Yet recent scientific studies propose that language “universals” aren’t simply prescribed by genes but that they arise from the interaction between the biology of human perception and the bustle, exchange and negotiation of human culture.

Language has a logical job to do—to convey information—and yet it is riddled with irrationality: irregular verbs, random genders, silent vowels, ambiguous homophones. You’d think languages would evolve towards an optimal state of concision, but instead they accumulate quirks that hinder learning, not only for foreigners but also for native speakers.

These peculiarities have been explained by linguists by reference to the history of the people who speak it. That’s often fascinating, but it does not yield general principles about how languages have developed—or how they will change in future. As they evolve, what guides their form?

Linguists have long suspected that language is like a game, in which individuals in a group vie to impose their way of speaking. We adopt words and phrases that we hear, and help them propagate. Through face-to-face encounters, language evolves to reconcile our conflicting needs as speakers or listeners: when speaking, we want to say our bit with minimal effort—we want language to be structurally simple. As listeners, we want the meaning to be clear—we want language to be informative. In other words, speakers try to shift the effort onto listeners, and vice versa.

All this makes language what scientists call a complex system. This means that it involves many agents interacting with each other via fairly well-defined rules. From these interactions there typically emerges an organised, global mode of behaviour, but this cannot be deduced from the local rules alone.

During the past three decades, complex systems have become widely studied by computer modelling: you define a population of agents, set the rules of engagement, and let the system run. Here the methods and concepts of the hard sciences—not so different to those that physicists use to model the behaviour of fundamental particles or molecules—are being imported into the traditionally empirical or narrative-dominated subjects of the social sciences. This approach has notched up successes in areas ranging…

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