As a western Washington resident, a great hike is never very far away, and I take advantage of this often. A quick call to a friend, an open afternoon, some snacks, a camera, and an adventure is underway. As we wander through the woods, pausing often to take a photo of some incredible tree or bush, the conversation always tends towards the nature of things, and why exactly they are the way they are. This can lead to incredible discussions delving deep into what exactly it means to be a human being. Or, end with a depressing: I don't know, and I wish I had enough cell phone service to Google it and find out.

These types of discussions are exactly the kind I want to write about here. So instead relying on my own background knowledge about a subject, and wild speculation, I want to try this same concept here in front of my computer with full access to the internet and its answers. To get started, I asked my friends and family through various social media outlets to provide me with their burning questions about human behavior. From there I'd scour research papers and answer them as completely and with as much high-quality factual support as possible, while simultaneously creating an interesting article in the process.

Thankfully, someone took me up on my offer. Here is @PorQueSenorita from Twitter with her question (compiled from multiple tweets):

@SamLarsen97 Why do we yawn? So far people say there is no known reason, but I would like to read more into it. Or why we laugh. How did that come to express enjoyment? What's the primitive use? Or why do we cry. Like why does water come out our eyes even overcome by certain emotions? How did that serve our primitive past?

I love a challenge. Since there are many questions layered in these tweets, let's tackle these questions one at a time, and one article at a time. To start, this article will focus on one topic:

Yawning

To answer your question, I read a very interesting article in the journal of Neuroscience & Biobehavioral Reviews and found this out for you:

First, those people who say there is no known reason for yawning, are sort of correct. Yawning is something we all do, but don't know much about. There are many theories, but most of them are lacking in evidence or proven false. If you're looking for a new career path, there might be steady work in the field of yawning research.

Here are common reasons people suspect we might yawn, and their current standing in terms of research.

1) Yawning is a physiological function. It helps the body function as it should, increasing respiration and the circulation of oxygen.

False: It is shown that people don't yawn when they need more oxygen or have excessive carbon dioxide in their blood. And after they yawn there's inconclusive evidence to support the idea that more oxygen is in the blood or brain as a result of yawning.

2) We yawn because we need to be more aroused.

False: While people do yawn when they are tired, there is no evidence to support the idea that the brain becomes more aroused as a result.

3) We yawn because we are sleepy, and yawning makes our brain slow down for sleep.

Inconclusive: There is inconclusive evidence to show that yawning makes us more sleepy.

4) We yawn to cool our brains. The cold air enters our body, passing over blood vessels cools blood heading to the brain to help us cool down and think clearly.

Inconclusive: People with overheating brains are inconclusively shown to yawn more, and the evidence is missing that yawning actually cools the brain down.

5) Yawning helps equalize pressure in our ears.

Inconclusive: The evidence is missing to show that people yawn because of changing middle ear pressure, although yawning does release the pressure in the middle ear. Try a yawn next time your ears feel pressured.

6) Yawning helps us communicate drowsiness, boredom or stress.

Strong Likelihood: The evidence shows that we do yawn when we are drowsy, bored, or stressed. And is further supported by evidence on the contagiousness of yawning. This theory is explained in detail below:

So your best answer is that yawning might be a purely social phenomenon.

As you are a human, who probably has the capacity to yawn, compare the following with your own experiences with yawning and decide if you agree with the social/communication hypothesis of yawning.

The amazing thing about yawning is that it is used as an almost universal symbol of sleepiness and boredom. In addition, yawning can be triggered by several body states and social contexts, such as the states of sleepiness and boredom that yawning represents. Observations in animals suggest that yawns might also happen when we are hungry or stressed.

So when we are in one of those social or physiological states, for example, let's say bored, a yawn is generated to non-verbally tell our social group that we are bored.

Of course, we don't yawn when we are happy or mad, that's because if there are too many triggers for a yawn we would become confused as to the meaning of a specific yawn, which would ultimately leave us at an evolutionary disadvantage. Yawning is a nice, easy, efficient way for everyone to communicate how they are doing socially and physiologically without a large amount of energy being expended.

You may have yawned several times while reading this article, and you may also be familiar with how when you watch when someone yawns you feel the urge to also yawn. This is normal, and actually pretty cool. How susceptible you are to someone else's yawn correlates strongly with your empathy skills. For example, people who have disorders related to difficulty with social interaction, such as autism or schizophrenia are not as likely to yawn when other people yawn. Additionally, yawning is even used as an indicator for people working with schizophrenia patients that the person is a mood that is easy to work with.

The article describes how regions of the brain activate when you watch or hear another person yawn, and while super fascinating (this whole article is, read it if you can), it's mostly large amounts of neuroscience jargon,so I'll summarize. When we watch other people yawn, regions of our brain responsible for motor imitation, empathy, and social behavior light up, providing neurological evidence to support the idea that yawning functions in a social/communicative role.

Also, another fascinating fact, children under the age of five aren't susceptible to contagious yawning. (Please, someone go yawn in front of someone under 5, then in front of someone over 5 and tell me the results.) This suggests that as a child's brain develops, how susceptible they are to "catching" a yawn is developing alongside a child's capacity for empathy and understanding of the mental states of others.

For other animals, we know yawning functions in a similar way for chimpanzees as it does for us, that is as a social/communicative role. However, other species that yawn (dogs, lions, etc.) may find different evolutionary advantages from the practice than we do. For example, some of the reasons we thought humans yawned, but turned out to be false, may actually be true for other species.

If we yawn to communicate, why do we still yawn when we are alone? Well, you yawn when your body is in a specific state, regardless of if there are people around or not. Humans first evolved the function to yawn, but haven't evolved a system that checks to make sure we only yawn when there are people around. Leaving us yawning when we are alone, broadcasting our status to an empty room.

There is a lot more research about yawning to do, but we've come a long way and have a pretty good guess as to why.

So yawn away! Tell the world how you're feeling with an easy to perform non-verbal action. Chances are someone out there is going to tell you how they are feeling right back without even realizing they're doing it.

That's it for part one! Stay tuned for part two where we tackle why exactly it is we laugh, how that might have evolved, and its use to primitive human beings.

Have a nice day!

If you have questions you'd like answered, send them to me at any of my contact methods listed on my profile.