Our ability to elaborately communicate is one of humanity's greatest superpowers. It allows us to retain and build knowledge across generations, cooperating at a global scale unlike anything else seen on Earth. But much about how this ability evolved is still a mystery, including its origins.
Recently, a team of researchers set up some experiments to explore the trope that our early human ancestors grunted at each other as a means of communication.
As the main function of language is to convey meaning across people, the researchers tested to see whether gestures or non-verbal sounds were more effective at getting meaning across.
Two groups of 30 volunteers across different cultures (Australian and Vanuatuan) had to try and convey specified meanings using either gestures or non-verbal vocalizations – a bit like a game of charades.
The same exercise was repeated with 10 sighted and 10 blind volunteers, who were tasked with producing the gestured or non-verbal communications, while a group of undergraduates tried to understand what they meant.
Successful communication was twice as high when the producers were gesturing than vocalizing, both cross-culturally and when blind or sighted, University of Western Australia cognitive scientist Nicolas Fay explained on Twitter.
Our #languageorigin paper is out @RSocPublishing— nicolas fay (@Nicolas_Fay) March 9, 2022
Communication success twice as high for gesture than vocalisation cross-culturally (Australia, Vanuatu) & cross-experientially (blind, sighted). Gesture's success due to its greater #universality @UWApsychhttps://t.co/FExsY0icLf
"These findings are consistent with a gesture-first theory of language origin," the team wrote in their paper.
The producers' gestured signals were far more similar to each other than vocal signals – even those produced by the blind volunteers. For example, everyone used the action of turning a key to represent the word 'lock', whereas there was no common sound they could use to embody the meaning in absence of the word itself.
"Gesture is more successful than vocalization because gestured signals are more universal than vocal signals," the researchers concluded.
However, as there were Ni-Vanuatan participants in the study who had relatively little understanding of Western culture, some differences did emerge:
"'Chain' was communicated differently: by manually simulating a pulling action (attached to something heavy) by an Australian Producer, and by manually simulating a throwing action (that represented a chain as an anchor) by a Ni-Vanuatu Producer," wrote Fay and team.
The study makes the assumption that our cognitive systems involving language did not significantly change in the up to 500,000 years since it's thought we developed language; of course, it may be that both forms of communication could have evolved simultaneously, the researchers note.
Simple things like screaming would be pretty universal too, so it's possible humans always used a combination of both.
But Fay and colleagues explain there is mixed evidence for this, with some small studies showing vocalization can impede the success of gestured communication. Other evidence also suggests we may have relied more on gestures first, including that gestures are used more in non-human primates than vocalizations, and young children and chimpanzees use similar gestures.
So it's possible that early on, before we came up with actual words, more complex meanings may have been articulated better by our very clever hands rather than our vocal cords.
This research was published in the Proceedings of the Royal Society B: Biological Sciences.