Did you just yawn while reading that title? 55% of people reading this are yawning right now. If you feel like your body is being held captive every time someone yawns, you are not alone. That’s because yawning is contagious, spreading from person to person. But also from animal to animal. You’ve probably seen your dog yawn or even your cat. Maybe you’ve seen a documentary where the videographer got the perfect angle of a lion yawning while lazing in its grassland habitat. But do herbivores yawn? Have you ever seen, for example, a giraffe yawn? How about a cow? The answer isn’t straightforward. Find out now!
Why Do We Yawn?
Unfortunately, no one really knows for sure. There are several theories.
- When we are bored or tired, our breathing slows, and we take in less oxygen. Yawning could be a way to bring more oxygen into the blood while moving carbon dioxide out.
- Yawning is known to stretch the lungs and their tissues. And often when we yawn, we stretch our bodies. These actions could be our system making us feel more awake by increasing our heart rate and flexing our muscles.
- It could also be a reflex that our bodies use to keep the lungs lubricated by distributing surfactant. Without this oil substance, our lungs could collapse.
Whatever the reason, it seems to be important.
Why Do We Yawn When Bored?
Another more recent theory for yawning is that it actually cools the brain, promoting arousal and alertness. Have you ever noticed that you yawn when you’re bored? What about when you first wake up? It could be your body trying to wake itself up. And the contagious aspect of a yawn could be coordinating alertness among members of a group. But again, this is yet another theory. The real answer is we still don’t know.
Why Does Yawning Feel Good?
Yawning often feels similar to a good morning stretch. Yawning happens in three stages: contraction, release, and muscle lengthening. The release stage is where we feel pleasure because our body is releasing tension. And maybe that’s all yawning is; an addictive release of tension.
Or maybe there’s some correlation between yawning, diet, and sleep.
Why is Herbivore Yawning Complicated?
Many used to claim that herbivores could not yawn. Herbivores can, in fact, yawn, just with a reduced frequency.
Studies show that carnivores yawn much more frequently than herbivores. But why is that?
Herbivores are relatively sedentary, they sleep very little, and they eat almost constantly. While carnivores have distinct inactive and active periods, sleeping between eight and 12 hours. Animals that follow a circadian rhythm seem to yawn more, especially right after waking and before going to sleep.
Some theories suggest that animals that eat low-energy-yielding foods and that are under pressure from predators will sleep less. The less it sleeps, the less it yawns. Animals, like carnivores, ingest a large amount of high-energy-yielding foods within a shorter period, allowing them to sleep for longer durations. This sleep cycle allows it to yawn more.
Do Giraffes Yawn?
An article published in 1992 quotes scientist Ronald Baenninger, who studies yawning. He states that after observing giraffes for 35 hours, he never once saw one yawn, concluding that they were the only vertebrate animal that doesn’t yawn. He reasons that the giraffe’s head is far from the heart and lungs and that their circulation and breathing have special adaptations that negate the need for yawning.
Is this true? Are giraffes really the only vertebrate animal that can’t yawn?
Well, it seems that no one else has done an updated study on this. So for now, the answer is we simply don’t know.
However, if you Google “giraffe yawning,” you will get some pretty awesome pictures that appear to be giraffe yawning. Either that or they are mid-song.
The photo featured at the top of this post is © YapAhock/Shutterstock.com
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