For all the talk about memes acting like genes and cultures evolving like organisms, no theory of non-biological evolution exists – but that could change.

In a study published today in the Proceedings of the National Academy of Sciences, linguists observed an artificial language evolve from random to ordered, naturally adapting in ways that assured its reproduction.



The findings duplicated a phenomena they'd already simulated on a computer, and hint at the earliest evolutionary origins of language – that cultural version of the opposable thumb, and the basis of humanity's civilizational complexity.

Even more tantalizingly, by showing that cultural evolution can be examined in a controlled setting, the study lays a framework for studying evolution outside its standard biological habitat.

"From Darwin onwards, there's been a mechanism for nature producing a design without there being a designer," said study co-author Simon Kirby, an evolutionary linguist at the University of Edinburgh. "We're used to that in biology. People have claimed that the same might happen in culture, and here we've shown a mechanism for language."

Kirby and his team showed people a collection of pictures paired with gibberish words, and later tested which pairs they could recall.

Whether or not the recollections were accurate, they were recorded and used as the basis of the next group's language training. As the process was repeated, patterns emerged: a certain word might be used, for example, to describe anything that moved horizontally, and another to indicate objects that bounced.

The language that emerged from the first set of iterations, said Kirby, was limited and simplistic. But for the next set, they discarded duplicate words. Confronted with this selection pressure – analogous, perhaps, to that exerted by nature on hunters with few words for their prey – the language became precise and highly structured.

Structure, said Kirby, was the key to a language being remembered.

"Over many generations, the grammar goes from ad-hoc and inexpressive into a language that's cleanly structured and expressive," he said.

"But what's evolving here isn't the agents" – the speakers – "but the language itself. It has its own evolutionary imperative. It wants to be passed on, and finds ways of doing that. We're its hosts."

Kirby believes the experiment touches on the same process that provided humans with the first languages. However, he said that linguistic evolution has largely stalled in modern times: though languages continue to change – witness Chinglish – and our communications skills vary, the underlying rules remain stable, having already found a successful form.

Some researchers have proposed studying religion in terms of cultural evolution, said Kirby, but he's not interested.

"That's an incredibly difficult thing to study. But with language, we have tons of data. It's the best case study we have for understanding evolution," he said.

He continued, "But people who are interested in culture more generally might take this work and study the emergence of design in a lab. I'd like to see how far that can be pushed. What kinds of adaptations would a culturally evolving practice come up with? How much of what happens around us, that appears rational and intelligently designed, is the product of a blind process?"

Cumulative cultural evolution in the laboratory: An experimental approach to the origins of structure in human language [PNAS] [not yet online]

Images: Snake warning by Alpha; error/complexity charts from PNAS.

*Update: A commenter raised some good questions about this study, addressed here.

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