Despite rules, language often evolves by chance

Language is always changing. Vocabulary is often generational, and slang terms can go out of style as quickly as they came in. The drastic differences between the writings of Shakespeare and modern American English beg the question: what exactly guides and determines the evolution of a language?

A new study set out to examine whether language evolves by a set selective force or random chance.

The study was conducted by both linguists and evolutionary biologists at the University of Pennsylvania and published in the journal Nature.

Researchers began mapping language through the years, similar to the way evolutionary biologists map genomes to see if one particular gene evolved to be dominant over time.

Experts from both fields worked together analyzing collections of annotated texts ranging from the 12th to 21st centuries, looking for changes to get a better picture of how language evolved.

The research revealed that some changes in language were guided by selective force, but other changes happened purely by chance.

“An individual happens to hear one variant of a word as opposed to another and then is more likely to use it herself. Chance events like this can accumulate to produce substantial change over generations. Before we debate what psychological or social forces have caused a language to change, we must first ask whether there was any force at all,” said Joshua Plotkin, the senior author of the paper.

For the study, the researchers examined three well-documented changes to the English language in order to decipher how what prompted these changes.

One of the changes analyzed was the regularization of past-tense verbs. The research team searched the sample texts for both irregular and regular verbs in past-tense forms, such as “dived” and “dove.”

Many of the irregular past-tense forms we use today are the result of purposeful selection that became taught and enforced. But there are also quite a few verbs whose current past-tense form is just the result of pure chance, or what simply “caught on.”

The researchers noted that random chance affected rare words and selective force was the guiding hand in changing common verbs.

The results of the study also found that grammar evolved through happenstance. For example, now we use “do” as in “do they say,” whereas 800 years ago we would’ve said, “say they.”

The study’s use of common methods in evolutionary biology is noteworthy and allows linguists to evaluate the evolution of language through the years in intense detail.

Because of this method, the researchers were able to find examples of random chance in the evolution of language and now have a more thorough grasp on the nature of how language changes.

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By Kay Vandette, Earth.com Staff Writer