Not Yawning at Pure Science

The world would be a different place if more people valued science, even as a hobby. In the same way that cities invest heavily in building indoor pools and artificial turf for amateur swimmers and soccer players, respectively, a society that relishes science for curiosity’s sake would alternately build centers for amateur research. The thought was inspired by a doctor’s answer to a radio listener’s question about yawning:

Unfortunately there’s not much research into finding out why people yawn. It would need a lot more work in the areas of psychology and group behavior, but there is not much interest in it. A lot of the granting agencies would probably consider the field a big yawn 1.

YawnWhy should we be enslaved to doing research only for what tickles the fancy (or serves the interests) of sponsors and agencies? And why should practicing science only be for those who get paid for it? I find yawning a great subject and the modest knowledge we’ve gained about the topic was enough to awake me this morning. But as interested as I was in the topic, due to the mysterious contagious nature of yawning, while I read less than 500 words, I yawned no less than four times.

Ultrasounds reveal yawn-like behavior during the first 3 months of development in the womb, suggesting that it goes far back in our evolution. The notion that it was a warning to predators is a pure guess and probably a wrong one. Something that triggers more questions and which is more substantial is the fact that two different neurotransmitters, dopamine and serotonin, increase the frequency of yawning. The experiments were done on rats, and since dopamine does not cross the blood brain barrier, a researcher either has to use a dopamine precursor such as L-dopa or an agonist—a compound that triggers the same receptors. From what I could gather, they used apomorphine, an agonist for two of the 5 known receptors of dopamine.

The above structures reveal the similarities between the two molecules. Apomorphine is synthetically derived from the biologically produced morphine by treating the opium- product with phosphoric acid. Morphine’s protruding OH group gets dehydrated by the acid, which rearranges the structure to that of apomorphine.

Compounds that fail to do likewise include CO2 and O2. Increasing either gas in the air we breathe has no effect on how often we yawn, which puts a major dent in the hypothesis that yawning is induced by a change in the composition of air.

Physiologically, a  morning yawn differs from a yawn in the evening. The former spreads beyond the face, as if to help awaken us. A night- yawn is more localized, and maybe its role is simply to prepare us for sleep. I’m guessing that if members of a social group share the same shelter it may be advantageous if a behavior helps others reach a state of alertness in the morning and a period of needed rest at night. That could explain the contagiousness of yawning.

Five hours after I’ve awakened, just writing about yawning has induced two more yawns on my part. How many on yours?

1 Irvin Mayers, Catching the Common Yawn, The Quirks and Quarks Question Book. 2002. CBC

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