For almost as long as stories have been told, stories have been deconstructed. For centuries, theorists, philosophers, and scholars have been pulling narrative structures apart, trying to pin down the most fundamental elements that give stories shape and meaning.

As far back as the 4th century BCE, Aristotle was dissecting story structures in this vein, and we're still doing it today. Of course, in the 21st century, we do things a little differently, with advances in computer science giving us the incredible ability to not just search for patterns within texts, but across entire canons.

To that end, a few years ago, researchers used language analysis techniques to sift through over 1,700 works of fiction, discovering six core emotional arcs resonating through most popular stories: trajectories, defined by alternating rises and falls in emotion, that formed the basis of their narratives.

Yet there is more to a story than emotional ups and downs. In the 19th century, the German writer Gustav Freytag came up with what is called 'Freytag's pyramid', building upon Aristotle's concepts of the beginning, middle, and end in the classical tragedy structure.

"At its essence, Freytag's framework suggests three primary processes in the unfolding of a story," the authors of a new study, led by behavioural analytics researcher Ryan Boyd from Lancaster University in the UK, explain in their paper.

"The first is the narrator setting the stage and establishing the context for the story. Once the elements of the story are established, plot progression begins through the movement of characters across time and space with increasing interactions among them. Moreover, the focal point of a story is the central conflict or cognitive tension that the characters must grapple with and ultimately resolve."

How do storytellers do all these things? The answer, Boyd and his team say, is through what they call 'invisible words': the hidden language of short and common 'function' words, including pronouns, prepositions, articles, conjunctions, and more.

Compared with 'content' words – nouns, verbs, adjectives, and adverbs – these function words might be a bit boring and well, invisible, but the way they're used in stories underpins a kind of universal blueprint across fictional works, the researchers say.

"At the most fundamental level, humans need a flood of 'logic language' at the beginning of a story to make sense of it, followed by a rising stream of 'action' information to convey the actual plot of the story," Boyd says.

In their study, Boyd and his team conducted a computer analysis of almost 40,000 fictional narratives, including novels, film dialogue, and short stories.

The results showed that across thousands of fictional works, writers tend to set the stage at the beginning of stories with lots of prepositions and articles, which help to introduce and locate characters and settings.

As plots progress, the language changes, with the amount of auxiliary verbs, adverbs, and pronouns starting to increase, while a rise in words reflecting cognitive tension peaks over the course of the story, falling as the narrative proceeds to its conclusion.

You can get a striking visual sense of how these language arcs shift and develop throughout stories at the researchers' website, which illustrates staging, plot progression, and cognitive tension in popular works like Wuthering Heights, Raiders of the Lost Ark, and Casablanca.

While not every story necessarily adheres to this use of language, most fictional works do, the researchers say, whereas a separate computer analysis of over 30,000 non-fiction works (including articles by The New York Times, TED Talks, and Supreme Court judgments) showed factual forms of storytelling seem to observe their own codes that are distinct from the fictional form.

As for why and how the distinctive language of storytelling emerged to be like this, nobody knows for sure – but it's possible that it says something about us, and about how we as a species absorb the information contained inside the stories we tell one another.

"At the heart of the issue is answering why consistent patterns of narrative processes emerge across such diverse stories," the authors write.

"It is possible that the structure found within the current research provides an optimal system for delivering narrative information… For example, if the layout of a narrative does not include information about the setting of the story early on, readers may find it difficult to understand a character's motivations, goals, and behaviours as the plot moves forward.

"From an evolutionary perspective, the structure of storytelling may provide a crucial way for people (or different groups) to share information… The optimal structure of storytelling, then, may originate from a natural inclination to first define objects/people and then assign action."

The findings are reported in Science Advances.