what looks like a yawn in some species is, in Commentaries fact, the same thing as a human yawn. One paper defines a yawn as “an extended gap- ing of the mouth followed by a more rapid closure.” I don’t think any of us perceives a crocodile with its mouth open, as yawn- Yawning, or Not Having Enough To Do ing. And just as far afield, it is unclear if a  bird displaying yawning -type movements, A c o l l e a g u e t o l d m e t h a t h e h a d j u s t s e e n diurnal. Sexual behavior of male rodents is in fact yawning, and similarly for a fetal a patient who had been bothered by yawn- from a strain with increased yawning was human. And what does one make of fish, ing for the past two years and wanted to reported. And there were even articles like Siamese fighting fish, which open their do something about it. It apparently was relating yawning to diseases, drugs and mouths and seem to yawn, although they not due to any identifiable disorder or hypothetical physiological mechanisms. don’t have lungs to take in air that primates medication. It turns out, unbeknownst to Is yawning so interesting or are do when yawning? my friend, that I had co-authored a case there a lot of researchers who are under- I suspect that all normal humans report on yawning in Parkinson’s disease employed? There are a few interesting yawn, although I don’t know if that’s (PD). My report described a man who things about yawning. The first is that it a fact. Perhaps there are people who had suffered from PD for many years and is contagious. The second is that yawning never yawn, no matter how tired or bored. suffered from severe clinical fluctuaations, is widespread in the animal kingdom and Would that have any meaning? What if the so-called “on-off” problem. He told is contagious in some of them. The third is absence of yawning was associated with me that about two minutes or so before that yawning has been identified in utero. some other unusual behavior? To be sure his medications “kicked in” and put him It seems that babies are not susceptible the association was more than chance, into an “on” phase he would yawn. He to contagious yawning, at least not from we’d need to evaluate a few patients with otherwise didn’t yawn, and he denied their mothers, which is, I think, a cruel similar behavior. But then, even if we sleepiness. I witnessed this once. He was trick on mothers. But most interesting of found a few people with the same sets of stuck in a wheelchair, unable to stand and all, at least to a neurologist, is that some unusual behaviors, until we found a ge- walk; he was stiff, slow, and pretty well patients with a hemiparesis from a stroke, netic or physiological link, any deductions frozen in place. He then began to yawn will raise an otherwise paralyzed arm dur- would be speculative, not scientific. and two minutes later he was dyskinetic ing a yawn, as an involuntary reflex. Attempting to draw evolutionary ad- but mobile, able to stand up and walk I suspect that yawning has attracted vantages to behaviors may be entertaining by himself. This had not been described attention simply because it is so universal and challenging but are unlikely to be good in the literature before, and, although I and yet carries no identifiable benefit. In science because we can never control all vari- hadn’t a clue as to what this “meant” in the fact, one can argue that yawning probably ables, and the basic driving force of evolution greater scheme of neurotransmitter physi- causes more trouble than it solves, at least is the random event. Most results of random ology, I was sure it meant something. in humans. Certainly the parent of a small, events are negative, but not all. Occasional I later learned that yawning was a very yawning child realizes that the child needs events are advantageous. Many are likely common reaction to one of the standard a nap. But just as certainly the teacher of a to be neutral, and if linked to something medications used in Europe for many years yawning child realizes that the child’s bore- advantageous, live on and prosper. to treat PD, apomorphine, but that medi- dom quotient has outweighed the interest Yawning is more interesting than the cation had not yet been tested in the US. level. Yawns are generally not well received palmo-mental reflex or the corneo-mandib- When I wrote my article(and I must point by the person who may be causing the con- ular reflex, but what is the point of a debate out that that little case report attracted dition. On the other hand, as a neurologist on the “meaning” of a yawn? While I like a more interest than any of the useful ob- who gives fairly frequent talks, I use the good argument, does anyone really care? servations or studies that I had published) incidence of yawning and myoclonic jerks the only thing I knew about yawning was as an inverse measure of how good a talk – Jo s e p h H. Fr i e d m a n , MD that it was contagious and that it occurred I’ve given. No yawns, myoclonic jerks or not only when humans are sleepy or bored, sleep attacks indicates a good lecture. Disclosure of Financial Interests but also when they are nervous. I think of the study of yawning in Lectures: Teva, Ingelheim Boehringer; When my friend contacted me re- non-human species as being a continuation General Electric Consulting: United Biosource; Buba- cently about his yawner, I did a Pubmed of “natural philosophy” of the 18th century, loo, Halsted, Reitman LLC; EMD Serono; perhaps, in some cases using 21st century search and was floored to find out how Genzyme; Teva; Acadia; Addex Pharm; many people had written articles about tools. When one tries to deduce the behav- Schwarz Pharma yawning. There was even an interesting ioral consequences or behavioral causes of Research: MJFox; NIH: Cephalon; exchange between two groups of experts yawning behavior in non-primate animals, EMD Serono; Teva; Acadia on the evolution of the yawn. There were one has trod onto a playground more philo- Royalties: Demos Press clever studies showing that yawning was sophical than scientific, even if one uses sci- contagious in birds, as well as primates, entific experimental techniques. After all, Corresponden c e and that the yawning was not simply as the authors argue, it is not at all clear that e-mail: [email protected] 234 Medicine & Health/Rhode Island