Cognitive Elements of Language Have Existed for 40 Million Years
30th October 2020
A new study completed at the University of Zurich has shown that humans are not the only beings that can identify rules in complex language-like constructions, monkeys and great apes can do so too.
A series of experiments based on an ‘artificial grammar’ were used by researchers at the Department of Comparative Language Science of UZH to conclude that the ability to recognise complex language-like constructions can be traced back to our ancient primate ancestors.
Language is known to be one of the most powerful tools to humankind. It allows us share information, views and culture.
“Research into language evolution is thus crucial if we want to understand what it means to be human,” said Stuart Watson, postdoctoral researcher at the University of Zurich’s Department of Comparative Language Science, in a university statement. But until now, little research has been done into how language originated.
Recognising connections between words
The team at Zurich University identified that the ability to understand the relationship between the words in a phrase, known as a “non-adjacent dependency”, is one of the most important cognitive elements needed for language processing. Non-adjacent dependencies can also be explained as dependencies between elements that are not contiguous.
They used a sentence, “the dog that bit the cat ran away”, as an example and explained that we know that it is the dog who ran away rather than the cat, even though there are several other words in between the two phrases. We know that because we are able to able to process the relationship between the first and last phrases.
A comparison between apes, monkeys and humans has now shown that the ability to identify such non-adjacent dependencies is likely to have developed as far back as 40 million years ago.
In the study, scientists took a new approach. They invented an artificial grammar in which sequences were formed by combining different sounds rather than words. This allowed them to make comparisons between the three different species of primates that don’t share the same communication system and see how they process non-adjacent dependencies.
The experiments were carried out with common marmosets (a monkey native to Brazil), chimpanzees and humans.
At the beginning of the experiment, researchers taught their test subjects to understand the artificial grammar in several practice sessions. The subjects learned that certain sounds and words were always followed by another sound. This mimics a pattern in human language, where we usually expect a noun followed by a verb. In the latter part of the experiment, researchers decided to play sound combinations that violated the previously rules learned by the subjects. This uncovered a strange behaviour in primates, they looked confused, stared at the speaker for twice as long as they did when they heard a familiar sound. This gave researches enough evidence to conclude that the animals had an ability to recognise grammatical errors.
Common origin of language
“The results show that all three species share the ability to process non-adjacent dependencies. It is therefore likely that this ability is widespread among primates,” says Townsend. “This suggests that this crucial element of language already existed in our most recent common ancestors with these species. Since marmosets branched off from humanity’s ancestors around 40 million years ago, this crucial cognitive skill thus developed many million years before human language evolved.”
