Language is a method of sharing thoughts. It is uniquely human: Many species communicate using pre-specified techniques, such as markings on a flower to direct bees, or gestures between mammals - but only humans have the flexibility of language. Language is, perhaps, the key evolutionary advantage the human race has over everything else on planet earth.

So how have we come to develop this trait?

That's the question Simon Kirby has spent the last 21 years trying to answer, now assisted by one of the world's leading research groups on the topic. Their research suggests that Darwin's model of natural selection is not a terribly good explanation. Indeed our culture actually shields us from natural selection, making our genes progressively less important to language as we develop. Simon goes on to speculate that domestification (being buffered from purely survival instincts) is a key condition of the emergence of language.

Kirby's evidence is especially interesting because, unlike Chomsky, he does not propose an innate underlying structure for the development of language. Such a dominance of unbounded cultural transmission would be both liberating and terrifying: Liberating because it suggests unrealised flexibility in language, especially forms enabled by future technology. Terrifying because (certainly from a relativist perspective, but arguably more widely) shared thought through language is what defines our very being.

This article is based on Simon's well-attended inaugural lecture to the University of Edinburgh, presented on 22 March 2011.

Beyond Darwin

Language is a:

  1. Universal trait, found in all humans.
  2. Adaptive trait, supporting human civilisation as it colonises the world (and beyond).

Those traits match a Darwinian model, however language has another unusual feature: Language is the capacity to learn language. Specifically what Simon Kirby called "iterated learning": Language is first learnt from older humans, then taught to younger humans, and so on over time. Each new generation takes the easiest language to understand, and passes it on.

This idea of "fresh minds" constantly being added to the system is important. The (unspoken) implication is that a sequence of humans can evolve more effectively than an individual human.

The result is a new kind of evolutionary system. One that retains the traditonal model of genetic improvement in human brains over generations, but adds a parallel path in which the generations also talk to one another, influencing the development of subsequent generations.

Studying Language Evolution

Existing languages can only be studied for changes in language - there are no records of the emergence of language. So instead laboratory experiments were conducted with an entirely new "alien" language:

In one experiment, words were randomly created by computer and assigned to pictorial objects. Sequences of people then played a Chinese whisper-style game using the words generated. They were then tested on how well they memorised these words. Words from the first sets of participants were then given to the next set, allowing the language to evolve as if being passed down between generations.

At first participants got almost everything wrong: The words were pure gobbledygook and hard to relate to the objects. However, over several iterations the language became easier to understand, with parts of the word consistently reflecting similar patterns in the object: For example, all black objects being prefixed with "ne", and all white objects prefixed with "nela".

So the prime driver for language becoming easier to understand is that it must be possible for children to learnt it. Language survives within us.

There is a clear cultural factor, but is biology also important?

A similar test was developed using a computer simulation, rather than actual people. This allowed gene evolution over generations to be modelled, in addition to language development.

Kirby expected a process of nativization, where culture is initially important, but later genes become increasingly dominant. He didn't find it: Instead culture shields us from natural selection, and ultimately there's no difference between someone born with language abilities and someone born without.

This doesn't entirely remove biological influence. For example, in questions Simon was asked whether there was a role for research into molecular genetics. He suggested that while there were specific genetic impairments to language learning, these might be better considered as impairments to the range of cultural behaviour required to learn language.


Kirby's system of cultural transmission transpires to be rather rare in nature. He suggested 2 criteria, each of which are found separately in some other species, but only exist together in humans:

2 examples were given of groups of animals that had been evolved towards greater communication by selective breeding:

Both examples suggest "domestification" (being buffered from purely survival instincts) lifts selection pressures. Kirby speculates that domestification is a pre-requiste for language. However, the evidence presented is weak: While it is logical that the dilution of the requirement to survive frees up mental capacity in an animal to communicate better, that doesn't imply a jump into language.

Overall, some combination of biological evolution, individual learning, and cultural transmission may explain where language comes from, but how we evolved to use language remains an open question. Just why are we so special?

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Similiar writings: Edinburgh, Evolution, Linguistics, Philosophy, Society.