We’ve seen fantastic football from the likes of Neymar Jr and Kylian Mbappé at this year’s World Cup, but they’ve also treated us to an unhealthy dose of play-acting and football con artistry. Quadruple rolls brought on at times by a mere Siberian breeze, often accompanied by devious squeals, were simply designed to deceive the referee into brandishing a colourful card or awarding a dangerous free kick.

While we all want to see such behaviour kicked out of the beautiful game, new research shows that the vocal aspect of faking pain – both on and off the football pitch – has evolutionary roots that may help explain how speech evolved.

Genuine pain causes both human infants and nonhuman mammals to produce cries, which are highly effective at engaging caregivers to respond and assist. Louder, longer and, in particular, rougher (think white noise) cries indicate greater pain. These are therefore harder to ignore, provoking more urgent responses. Interestingly, pitch doesn’t increase gradually with rising levels of pain in human infants. Instead, the pitch tends to increase rather abruptly after a threshold of high pain has been reached.

From stubbing toes to childbirth, adults cry out in pain too. But understanding these anguished noises in a scientific way isn’t easy – gone are the days where giving participants electric shocks are easily justified in the name of research. We do however know that midwives can judge the stage of labour a woman is at from her vocalisations during childbirth. This suggests that adult pain cries also communicate useful information about the intensity of pain experienced.

But the voice functions as more than just a transparent window into a person’s pain level. Our brains process pain differently depending on context, mood and attention. For example, our pain response may be exacerbated if anxiously anticipating an imminent injection.

Faking it in the lab

Anecdotal evidence suggests that we can deliberately exaggerate, minimise and fake pain to serve our own needs. All of us have made a bigger song and dance over an injury than we needed to at some stage in our lives, just as we’ve stifled outbursts in embarrassing or formal situations. We’ve also watched actors writhing in pain we know full well doesn’t exist, yet helplessly squirmed and empathised anyway.

But until now nobody has scientifically investigated to what extent we can convincingly modulate and fake responses to pain. In our latest study, published in Bioacoustics, we recruited 60 trainee actors to express three levels of increasing pain. We also asked 64 listeners to rate how much pain each vocalisation conveyed. We then investigated which aspects of their voices the actors manipulated – and how this influenced listeners.

In the complete absence of pain, we found that the actors used their voices to communicate pain intensity in a highly similar fashion to human infants. We found that they were indeed highly successful at manipulating listeners’ pain ratings, so it seems we really are quite skilled at faking pain.

Evolutionary meaning

For our ancestors, navigating an environment with danger at every turn, this ability to convincingly simulate or exaggerate pain – and, crucially, elicit more urgent aid – may have provided a vital survival advantage. Initially, our ancestors’ vocal repertoire consisted only of automatic responses to environmental triggers, which solely functioned to communicate information that affected their chances of survival or reproductive success. For example, threat elicits roars, which advertise fighting ability – allowing individuals to compete for resources without needing to engage in costly combat.

It may seem that such information must remain honest to prevent a communicative system from breaking down. What’s the point of paying attention to a vocalisation if you can’t trust its content? But, in the context of the need to survive, there are great potential costs to ignoring a vocalisation whose honesty is questionable. After all, if someone nearby is in pain, then you could soon be too if you don’t err on the side of caution. Under these circumstances, vocal exaggeration and deception strategies can take advantage of the high stakes and flourish.

This vocal trickery was likely to have been a key step in our progression from primitive nonverbal noises to complex, controlled speech. Developing the ability to produce and modulate pain cries and other vocalisations at will represents a watershed moment – after which point the voice became not just an honest window into a vocaliser’s attributes, but a social tool with which to influence others.

Eventually, our vocal control would have become sufficiently advanced to allow us to produce new, arbitrary sounds, whose structure and meaning we agreed on culturally, rather than being determined by our physiology and evolutionary processes. Or in other words: the first words.

Some nonhuman mammals are further down the road to speech than you might think. Many are able to exaggerate their body size when producing aggressive vocalisations, and recent evidence indicates that great apes are capable of greater vocal control than previously assumed. Some mammals even have a few vocal deception strategies up their sleeve. Take the capuchin monkey for example, which can produce deceptive alarm calls that are acoustically indistinguishable from genuine alarm calls elicited by predators.

But this vocal “cheating” is not without risk – the costs of losing the trust of group members through providing dodgy information can quickly leave one fending for oneself. So while deception may have been a fundamental factor in creating the vibrant and varied communicative tools we possess today, it must be handled with care.

While Neymar was able feign pain and pull the wool over the referee’s eyes a few times, eventually reputation preceded him in his team’s hour of need – as Brazil found out against Belgium. Sometimes, deception can even be deadly – just ask the boy who cried wolf.