Women twice as likely to 'catch' a yawn as men
Yawns are twice as "catching" in women as they are in men, a study has shown.
The finding can be explained by the fact that women are the more empathic sex, say researchers.
Growing evidence suggests that yawn "contagion" is closely linked to empathy, the ability to step into the shoes of others and understand what they are feeling.
Even in higher animals, such as apes and monkeys, yawns can be catching. One individual yawning can trigger an epidemic of yawns in their neighbours.
Research has shown that in apes, females are more susceptible to yawns than males.
Now a new study has shown that the same is true for humans.
After observing 1,461 yawning bouts in everyday situations over a period of five years, a team of researchers found that women were roughly twice as likely to "catch" a yawn as men.
None of the individuals involved were aware they were being watched.
Yawn contagion rates were also found to be significantly lower between acquaintances than between friends and relations.
The scientists, led by Dr Elisabetta Palagi, from the University of Pisa in Italy, wrote in the journal Royal Society Open Science: "The completely new finding of this study is that under natural conditions women from our population sample contagiously yawned at significantly higher rates than men.
"This result further supports the empathic ground of yawn contagion, in the light of the existing psychological, clinical and neurobiological evidence in favour of higher empathic abilities of women compared with men."
Previous studies have shown that yawn contagion is by no means universal. Under laboratory conditions 40% to 60% of individuals are never "infected" by other people yawning.