Diseases are not the only things that can be contagious; yawning is catching too. And while most of us have long recognised this phenomenon, thanks in part to falling 'victim' to it, no one succeeded in shedding scientific light on this mystery ... until now. Researchers in Italy have offered the first behavioural evidence that yawning is a fast and frequent effect between people who share an empathic bond, like friends and family members. The results were published in the journal PLoS ONE.
Researchers from the Natural History Museum at the University of Pisa and the Institute of Cognitive Sciences and Technologies (CNR-ISTC) in Italy say yawn infectiveness is a sign of emotional 'contagion'. According to them, spontaneous yawning, not solicited by other yawns, evolved as early as bony fish that are over 200 million years old.
'Depending on the animal group considered, a yawn can indicate stress, boredom, fatigue, or signal an activity change, for example after waking up or before going to bed,' explained Elisabetta Palagi of the CNR-ISTC, one of the authors of the study. 'Contagious yawning is a complete different, and more "modern" phenomenon, demonstrated, so far, only in gelada baboons, chimpanzees, and humans. It has also been hypothesised for animals with high cognitive and affection abilities, such as dogs. In humans, a yawn can usually be evoked by another yawn within five minutes.'
For the purposes of their study, the researchers obtained information from over 100 adults in Italy and Madagascar over a 12-month period. The data corresponded to more than 400 'yawning couples' of different nationalities, and with a different degree of familiarity: strangers, acquaintances, friends and kin. The team observed people in various natural contexts including on the train, at work and during meals.
'A vigorous statistical analysis based on linear mixed models ... has revealed that the presence and the frequency of contagion (if and how much it occurs) is not influenced by differences in the social context or in the perception modality,' said lead author Dr Ivan Norscia of the University of Pisa. 'What appears to be most important in affecting contagion is the relationship quality that links the yawner to the "yawnee". It is, in fact, more likely that a person [will] "yawn back" if the first yawner is a loved one. The study reveals a specific trend: the rate of contagion was greatest in response to kin, then friends, then acquaintances, and lastly strangers. Also the response gap (latency) — or how long it takes to a person to respond to someone else's yawn — is shorter in friends, kin and mates than in strangers.'
Commenting on the findings, the CNR-ISTC's Elisabetta Visalberghi said: 'The results of this study are supported by several neurobiological clues from previous reports. Such reports have shown that some of the brain areas activated during yawn perception overlap with the areas involved in the emotional processing.'