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Language and communication

Words subject to survival of the fittest

Concrete words, arousing words, and those learned early cling on to usage, and are more likely to be preserved in language, according to new research.

26 January 2024

By Emma Young

Charles Darwin likened the evolution of languages to the evolution of an organism. “The survival and presentation of certain favoured words in the struggle for existence is natural selection,” he wrote in The Descent of Man. Some modern researchers view language in the same way, and argue that certain words out-compete others, and are more likely to survive. But what makes these words ‘fitter’ than others? The answer, according to a new study in PNAS, lies at least partly in the way our brains learn and process words. 

In the first of two experiments, Ying Li at the Chinese Academy of Sciences and colleagues analysed data from an earlier online study, in which participants read short stories (in English) that had been created by the researchers and then had to retell the story ‘in their own words’. These re-told stories were given to a fresh group of participants, who received the same instructions. This process was then repeated again, meaning that ultimately each of the 97 original stories were retold 2,695 times in the first generation, 6,474 in the second, and 7,428 in the third. 

The researchers behind the new paper looked at which words were preserved in re-tellings — or, to put it another way, which words out-competed the others. Their analysis of these results revealed that three variables linked to cognitive processes went a long way towards explaining why some words were ‘fitter’ than others. 

The first variable was the age at which the words are typically learned, with words learned earlier in life being slightly more likely to be preserved. The second was a measure of ‘concreteness’; they found that a more concrete word (like dog), which is easier to see or imagine than a more abstract word (like animal), was more successful. In fact, concreteness had a far bigger impact on word preservation than age of learning, with an increase of one standard deviation in the concreteness measure being linked to a 45% increase in the likelihood that that word would be preserved in the subsequent re-telling. The third variable was a measure of the word’s ‘arousal’ level. Words that were more arousing — such as ‘fight’ and ‘sex’ — were more likely to be preserved than less arousing, emotionally neutral words. 

In the second part of the study, the team analysed vast repositories of texts in English written between 1800 to 2000. They looked at changes in the frequency of words over these two centuries. And they found that, as in the first part of their study, the age of acquisition, concreteness and arousal level of a word were the linguistic factors that give some a selective advantage.

Earlier research has found that more concrete words are more memorable, which, the researchers write, could explain why they are more likely to survive. This extends to words that are learned earlier in life, which may be less vulnerable to the impacts of age-related memory deterioration, giving them a survival advantage. When it comes to the arousal findings, other research has found that emotionally arousing photos, for example, are more memorable than dull ones — and this new work suggests that the same may be true for words. 

The consistency between the results from the first and second parts of the study is clear. Together the researchers write, these two sets of findings provide evidence that languages undergo ‘cognitive selection’ for words that are easier to process, recall, and reproduce.

Of course, languages do also develop and expand. Changing social, emotional, and technological conditions (such as the development of social media) lead us to coin new words. So, too, does the drive to find new ways to express age-old ideas and feelings, which can manifest as new in-group slang. “These new words may replenish the vocabulary that cognitive selection culls in times of increasing competition,” the researchers write. But whether or not they survive in the long run may depend at least partly on those same fundamental cognitive factors. Our environment may change, but, as the researchers write, “the mind remains relatively stable.”