A common issue, even in our Internet Information Age is that, even with so much information available, we rarely update our older learned information. Thus, nearly everyone, including the professionals, leaders and experts we rely upon for authoritative information, can carry around and pass on wrong views for years.
Take the yawn, for example. Most of us learned and have observed first hand that yawning is contagious. For years I’ve believed that some people are better at detecting low oxygen than others, therefore, it became evolutionary advantageous to yawn whenever anyone else was. Gork in a cave yawns when the O2 gets low, the others who yawn too survive to reproduce and the trait is passed on by natural selection. Sounds reasonable, but as it turns out, this “low oxygen theory” for yawning is wrong.
Instead, contagious yawning in 2014 was seen, supported by research, to reduce brain temperature, and in that way to increase mental function and alertness.
… accumulating research [suggests] that the underlying mechanism for yawning, both spontaneous and contagious forms, is involved in regulating brain temperature. In turn, the cooling of the brain functions to improve arousal and mental efficiency. The authors of this study suggest that the spreading of this behavior via contagious yawning could therefore function to enhance overall group vigilance. – SciDaily
Interestingly, there seems to be a specific temperature (20ºC which is 68ºF ) around which more contagious yawning occurs. Contagious yawning decreased, researchers found, when temperatures were high about (37° C which is 98.6 °) and also when they were very low. The frequency of yawning decreases as ambient temperatures increase and approach body temperature.
… when you see someone in your group yawning (and thus securing a cold brain that allows them to be alert), it might be adaptive to also be alert, as your group member might have seen something threatening, and consequently, you also want to cool your brain for optimal homeostasis, and thus you yawn, too.” – MedicalNews
This makes sense, but is it the full story? For now, this is what I’ve updated my understanding to be: we yawn to cool the brain to increase alertness. This is likely true for “pretty much all vertebrates,” including all mammals, except for cetaceans, such as whales and dolphins, which do not yawn, based on current understanding.
Keep learning and update what you know. There are some pleasant surprises along the way if you do.