Most people have seen examples of Contagious Yawning in humans. If one person in a group yawns (or convincingly feigns a yawn) it's often quite hard for others to resist. Current estimates are that 40-60% of human yawns are 'contagious'.

Contagious yawing has also been observed and scientifically documented in many other animals including :

• Chimpanzees
• Bonobos
• Orangutans
• Macaque monkeys
• Gelada baboons
• Wolves
• Domestic dogs
• Rats
• Budgerigars
• Sheep
• Elephants

Contagious Yawning can also happen between species. A team at Birkbeck College, University of London, recently performed the first formal research to document Trans Species Yawn Contagion. [ man > dog ] ( Ref. Biology Letters Volume 4 Issue 5.)

Another recent study, from the Department of Psychology, Hiram College, US, can be found in Animal Cogntion 12(6):833-837.

There are theories regarding the possible evolutionary advantages to yawn contagion, for example, that contagious yawning may be part of a neural mechanism involved in empathy. ( Ref. Cognitive Brain Research Volume 23, Issues 2–3 )

But a full explanation is currently lacking.

Also see Yawningplugin-autotooltip__plain plugin-autotooltip_bigYawning

The physical and psychological sequences which occur during the yawning process have been widely studied. Nevertheless, the reasons for yawning are disputed and unclear - as is identifying an evolutionary reason to explain the need for it.

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