Question

why is yawning contagious?

Answer 1

About half of adults yawn after someone else yawnsdue to a universal phenomenon called “contagious yawning.” Contrary to popular belief, a new study from Duke University suggests that contagious yawning is not strongly related to variables like empathy, tiredness, or energy levels

Answer 2

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 researchers emphasized that a better understanding of the biology involved in contagious yawning could ultimately lead to a better understanding of illnesses such as schizophrenia and autism. 

A 2010 study from the University of Connecticut found that most children aren't susceptible to contagious yawning until they're about four years old—and that children with autism are less likely to yawn contagiously than others.

In a study of about 30 6- to 15-year-olds with autism spectrum disorders (ASD), the Connecticut researchers found that children with ASD were less likely to yawn contagiously than their typically developing peers. Children with more severe autistic symptoms were much less likely to yawn contagiously than those with milder diagnoses.