Yawning: It Isn't About Oxygen Anymore

Biology 103
2003 Second Paper
On Serendip

Yawning: It Isn't About Oxygen Anymore

Abigail Fritz

Have you ever wondered why yawns are contagious; have you ever been in class and seen someone across the room yawn and found yourself following along? Have you ever been reading a book and, upon coming across a yawning character, been moved to stretch out your own face muscles? Most likely these things have happened to almost everyone more times than they can remember. I cannot tell you how many times I have yawned in the process of researching and writing this paper. A friend of mine began to yawn uncontrollably as I discussed my ideas with her.

Yawning is a phenomenon that occurs for most people many times a day, yet it is not one that has been studied extensively by researchers. This is an unfortunate fact because he more I read about yawning and thought about number of situations in which it occurs, the more eager I became to better understand what is behind humans' tendency to yawn.

At first, one might see yawning as a silly phenomenon to spend time studying because, well, it is just what happens when we are tired; but it is more complicated than that. We yawn when we are tired, but also when we wake up, when we are bored, and even simply because we see others doing it. When one delves into the unknown of what causes a yawn, he or she will become intrigued by how mysterious the occurrence is and surprised about how little we known about it. The following will discuss the many theories that have been put forward regarding the phenomenon and its contagious qualities and explore the implications and problems with these various theories.

There exist both theories as to why we yawn and theories as to why yawns are contagious. Let us first look into why we yawn. The theory that has long been thought to explain yawning, and the one that has often used in medical textbooks, is that we yawn due to low oxygen levels in the lungs (1). When we are in a resting state, we make use of a very small percentage of our lungs' capacity and are only using the air sacs, or alveoli, in the bottom of our lungs (1). The alveoli partially collapse when the air sacs stop receiving fresh air, cueing our brains to induce a yawn (1). This theory has been largely cast aside, however, because our lungs do not necessarily detect oxygen levels (8).

The interesting contrast to the low-oxygen theory is that some observations have been made that suggest that fetuses in the womb yawn. Doctors have observed fetal yawning in utero at twenty weeks gestation and noted a 'fetal yawning movement' (7). Mouths opened widely resembling a yawn with qualities quite different from those of a brief moment of swallowing and the mouth remained open for around two minutes (7). These observations do not support the oxygen theory because fetuses in utero do not yet have ventilated lungs (8). Other doctors have responded to these observations in the New England Journal of Medicine saying that, "there is too much of a range of variation in the observations and that there is a discrepancy in the use of the anatomical criterion of retraction of the tongue to characterize the fetal yawn, whereas in yawning adults, the tongue is extended" (7).

One interesting study on the cause of yawning hypothesized that, "contagious yawning occurs as a result of a theory of mind, the ability to infer or empathize with what others want, know, or intend to do. Seeing or hearing about another person yawn may tap a primitive neurological substrate responsible for self-awareness and empathic modeling which produces a corresponding response in oneself" (2). Researchers tested this hypothesis by observing individuals that exhibited schizotypal personality traits. They felt that those traits would inhibit a person's ability to process information about the self and would therefore lower their tendency to yawn contagiously (2). Their lowered ability to identify with another's state of mind would prevent them from 'catching the yawns' as a result of empathizing with someone seen yawning. The researchers' findings were consistent with their hypothesis and could aid in explaining why schizophrenics rarely catch the yawns (3). Another experiment conducted at New York State University's Department of Psychology declared similar findings stating, "We have also shown that individuals who score higher on schizotypal personality traits are less likely to show contagious yawning because of a fundamental impairment of self-processing" (9).

There are evolutionary theories for yawning. Robert Provine, professor of psychology at the University of Maryland Baltimore County, suggests that yawning is about "transitions in the body's biology" (5). This theory might support observations that suggest fetal yawning. Perhaps it aids in maintaining the balance of amniotic fluid. Provine goes on to say that yawning can occur not only when transitioning from a state of alertness to a state of sleepiness, but also from a transition from sleepiness to alertness (5). He makes the point that, "at track and field events, sometimes you'll find participants in the race of their life will be standing around on the sidelines or in the starting block and they may be yawning. Or before a concert, a musician may yawn to prepare for an increasingly energized state" (5). The evolutionary theory behind this is that yawning is a result of synchronizing behavior based on these changing states of alertness (5). The changes in your body that "are brought about by yawning are synchronized in everyone that's doing it" (5). The associate professor of physiology at the Lake Erie College of Osteopathic Medicine suggested a similar theory, stating that, "the contagious nature of yawning is most likely a means of communication within groups of animals, possibly as a means to synchronize behavior; therefore in humans it is most likely vestigial and an evolutionarily ancient mechanism that has lost its significance" (8). Just as our teeth have gotten smaller as we have evolved, so has the significance and meaning of the yawn.

Continuing along the lines of evolution, one might consider the yawn in term of a link to our "furrier days" (6). At that point in human evolution, we would yawn to show our teeth, which is why zoologists speculate animals yawn. According to this theory, when someone near us yawns, our "subconscious Neanderthal responds to the 'aggressive challenge' with an I-have-big-teeth-too-yawn" (6). As the writer of the article that discusses this theory agrees and teases, the 'furry days theory' seems to be a fairly far-fetched argument. It makes sense that animals show their teeth to intimidate other animals, but should we call that a yawn or equate that act with the human act of yawning? It is hard to imagine that we are subconsciously putting forth an "aggressive challenge." Consider throwing the theory of evolution out the window. We cannot be certain that humans have evolved from monkeys. If, in fact, we have not, how might we explain the yawning phenomenon? I would like to suggest two theories that seem to me to bear the most significant and convincing evidence for why we yawn and why yawns are contagious.

There have been so many theories, and just as one of them starts to become convincing, a different discussion presents information that suggests such a theory does not make sense. Despite these discrepancies, we have to begin to make sense of the act somewhere. Yawning is undeniably a contagious phenomenon that I am convinced is more than a result of evolutionary adjustments and that has become an act having little meaning and that is insignificant to our function as humans. The idea of yawning being about transitions in the body's biology is my "first pick" as an explanation for yawning and into which I am inclined to look further. Through some discussions with my friends, it became clear that they not only yawn when they are tired, but many of them also yawn when they wake up in the morning. Further, I have been surprised to find myself yawning on numerous occasions because I was not feeling any hint of being sleepy, but perhaps it occurred at moments when something was happening for which I needed to be more alert than normal, and my body therefore responded with a yawn.

The theory of mind suggestion is my "second pick" and the experiment described earlier carried some very intriguing implications. It was interesting to think about the phenomenon in terms of personality traits that might lessen a person's chance to experience the same phenomenon. The fact that a schizophrenic patient does not 'catch the yawns' as easily as someone without the disease because of their difficulty in identifying with another's state of mind is convincing information in support of the theory of mind concept. Humans are very receptive organisms that respond quickly to the feelings and emotions of the individuals around them. We often find ourselves being very connected to those that we are close to in terms of interpreting moods and finding ourselves saying the same things at the same time or finishing sentences. These human tendencies convince me that a theory of mind that explains yawning is a very likely one. Our capabilities to connect with others on personal, intellectual, and subconscious levels are qualities of the human experience that are very difficult to explain, but that exist nonetheless. These characteristics are what make us such complex organisms.

References

1) NBC News Health , Theory on why we yawn.

2) Good study on schizotypal patients

3)Nature: Science Update, Links self-awareness and yawning

4)National Library of Medicine, The Neuropharmacology of Yawning

5)NBC News, Yawning and its Contagious Tendencies

6)Island Scene Online, Speaks on why a yawn can be more contagious than the flu

7)Fetal yawning in utero, Addresses observations of fetal yawning at 20 weeks

8)Scientific American, Addresses why we yawn and why yawning is contagious

9)Article in press at www.elsevier.com, Discusses the impact of schizotypal personality traits