You only need to read a snippet of Shakespeare to see how language changes over time, but how do those changes come about? Both through a kind of natural selection and through random chance, according to new research.

What's more, random chance plays a bigger part than previously thought – and the researchers also concluded that fighting against grammar changes is futile. They're going to happen, no matter how many times you try and correct them.

Social, cognitive, and other factors combine to create an evolutionary pressure on language over the course of centuries, says the team from the University of Pennsylvania, and that combines with simple luck to produce the spellings and grammar rules we have today.

"Linguists usually assume that when a change occurs in a language, there must have been a directional force that caused it," says one of the researchers, Joshua Plotkin.

"Whereas we propose that languages can also change through random chance alone."

Digging into databases holding hundreds of thousands of texts and millions of word samples, the team looked at both regular and irregular past-tense verb forms, like "dived" and "dove", or "wed" versus "wedded".

Using an analytical approach previously used to study natural selection in microbial populations, the team looked for evidence of selection in word evolution.

For example, whereas swimmers 200 years ago would probably have "dived", today many American English speakers would say they "dove" – a change that can be linked to the arrival of cars and the use of "drive" and "drove" in the language.

The use of "quit" instead of "quitted" also matched up with the increase in the rhyming irregular verbs "hit" and "split", with rhymes like these acting as a "gravitational force" dragging other words along with them, according to the researchers.

However, most of the verb changes seemed to be more likely the result of random chance rather than any kind of selective pressures, particularly rarely used verbs.

"An individual happens to hear one variant of a word as opposed to another and then is more likely to use it herself," says Plotkin. "Chance events like this can accumulate to produce substantial change over generations."

For example, the rise of "do" in sentence structure – saying "you don't say?" rather than "you say not?", as was common back in the 1400s – can't be linked to any kind of selective pressures based on the study's analysis.

We're only just getting the opportunity to analyse language in this kind of detail and over these kind of time spans, thanks to the large databases that are now available. The researchers note that plenty of further study is required to understand these shifts further.

However, as far as the verbs and words analysed in this study go, it appears only some of our language evolutions can be explained away with recognisable patterns. What's more, if you're going to nitpick about major shifts in grammar use, you're up against fate itself.

"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," Plotkin told Nicola Davis at The Guardian.

"The grammarians might [win the battle] for a decade, but certainly over a century they are going to be on the losing side."

The findings have been published in Nature.