Linguists say that random chance plays a bigger role than previously thought in the evolution of language – but also that ‘English is weird’
Comparisons have long been drawn between evolution and changes in language, with experts noting that preferences such as a desire for emphasis can act as a type of “natural selection”, affecting which words or forms of grammar are passed on between generations.
But a new study shows that another evolutionary mechanism might play a key role : random chance.
“Whether it is by random chance or selection, one of the things that is true about English – and indeed other languages – is that the language changes,” said Joshua Plotkin, co-author of the research from the University of Pennsylvania. “The grammarians might [win the battle] for a decade, but certainly over a century they are going to be on the losing side.”
Writing in the journal Nature, Plotkin and colleagues describe how they tracked different types of grammatical changes across the ages.
Among them, the team looked at changes in American English across more than one hundred thousand texts from 1810 onwards, focusing on the use of “ed” in the past tense of verbs compared with irregular forms – for example, “spilled” versus “spilt”.
The hunt threw up 36 verbs which had at least two different forms of past tense, including quit/quitted and leaped/leapt. However for the majority, including spilled v spilt, the team said that which form was waxing or waning was not clearly down to selection – meaning it is probably down to chance over which word individuals heard and copied.
“Chance can play an important role even in language evolution – as we know it does in biological evolution,” said Plotkin, adding that the impact of random chance on language had not been fully appreciated before.
For just six of the 36 verbs, the rise of one form over another was clearly not only down to chance, but was largely a result of active preference – akin to natural selection.
Specifically, “woke” is increasingly preferred over “waked” and “lit” more popular than “lighted”, while “weaved” and “snuck” are on track to eventually overtake “wove” and “sneaked”, respectively.
The study also revealed that a flower today is more likely to be “smelled” rather than “smelt” and that the neighbour’s cat probably “dove” behind the sofa – although, as Plotkin notes, British felines remain more likely to have dived.
But there was a puzzle. “The prevailing view is that if language is changing it should in general change towards the regular form, because the regular form is easier to remember,” said Plotkin. However, four of the six verbs show a rise in the irregular form of the past tense.
That, the team note, might at least in part be down to whether the word sounds similar to other commonly used words of the age. For example the increasing popularity of “dove” rather than “dived” in American English coincides with the development of cars, and hence the rise of soundalike “drive” and past tense “drove” in describing journeys. The team add that they suspect similar effects might be at work in a number of the verbs that currently look like they might be changing by chance alone.
The authors add that the research suggests rare words are more likely to vary over time and be subject to random chance.
The study also explores the use of negation in sentences, such as “I say not”, across English texts dating from the 12th to the 16th centuries, revealing that the placement of the negative word has changed more than once due to selection, possibly because of a desire for emphasis.
“There a was period of time where double negation … was the way to negate things, just as it is in French today,” said Plotkin.
Dr Christine Cuskley, from the Centre for Language Evolution at the University of Edinburgh, agreed that similarities to commonly used irregular verbs could affect which form of past tense is on the rise.
But she said that it was likely that there were other pressures affecting which form of a past tense is favoured. What’s more, Cuskley added, it is not clear if the conclusions from the latest research could be applied to other languages.
“English is weird,” she said.