People are less likely to succumb to contagious yawning as they age, according to a new study.
Yawning is linked with empathy and might have a connection with the need for group vigilance during the ancient hunting gathering days. Now, researchers at Duke Center for Human Genome Variation have found that yawning might be more than just an empathetic reaction passed down through the ages. Their study also shows that older adults are less likely to yawn after seeing others than their younger counterparts.
"The lack of association in our study between contagious yawning and empathy suggests that contagious yawning is not simply a product of one's capacity for empathy," said study author Elizabeth Cirulli, Ph.D., assistant professor of medicine at the Center for Human Genome Variation at Duke University School of Medicine.
The phenomenon of yawning is not just documented in human babies but also in chimpanzees. A recent study had also showed that dogs yawn when they see their human companion yawning.
Studies based on people with autism and schizophrenia have shown that these people rarely catch the contagious yawn. According to researchers, understanding why humans yawn and why this behavior is different in autistic individuals could help improve our knowledge about mental disorders.
For the study, researchers recruited 328 healthy volunteers. All participants underwent a series of tests that assessed their intelligence, empathy levels and sleepiness.
Researchers then showed each participant a video where people were yawning and counted the number of times the participants yawned.
Contrary to previous studies, researchers didn't find any relation between intelligence, empathy and yawning. Instead, they found that age explained 8 percent of the variation in test result, meaning that responses to contagious yawning change with age- the older you are, the less likely are you to catch contagious yawning.
In the next part of the study, researchers will be looking at genetic factors that influence yawning.
"It is possible that if we find a genetic variant that makes people less likely to have contagious yawns, we might see that variant or variants of the same gene also associated with schizophrenia or autism," Cirulli said in a news release. "Even if no association with a disease is found, a better understanding of the biology behind contagious yawning can inform us about the pathways involved in these conditions."
Yawning isn't an isolated behavior that spreads like an infection through the group. Previous research has shown that other behaviors including laughing and clapping are contagious. Clapping is a natural way of showing appreciation. Applause is seen as a stable part of human culture and something that babies learn to do quite early in life.
The study is published in the journal PLOS ONE.