A new study has found that contagious yawning among chimpanzees is more common when set off by dominant males.
Researchers in the Netherlands found that video clips of male chimps yawning were twice as likely to induce yawning than clips of females.
The New Scientist reported that the study filmed 15 chimps yawning.
They then showed those clips back to the chimps individually to see if they would yawn in turn.
Watching clips of dominant male chimps yawning was twice as likley to spur the activity.
Discover magazine previously reported that chimps also tend to yawn when an animal they know does it, rather than a stranger.
The study was published in the journal PloS One.