Why Do Onions Make Us Cry?

You’ve probably experienced the burning and tearing in your eyes when you cut onions. But why do onions affect our eyes the way they do? What kinds of chemicals are in play?

Well, here it is.

When onions grow in the soil, they absorb many nutrients including sulfur. When an onion reaches our kitchen counter, it does not emit any gases and no matter how long we stare at the onion, we will not tear.

But when we cut into the onion, we break the cell membranes and allow the chemicals that are normally separated by their compartments to spill out and mix. Some of these chemicals include “amino acid sulfoxides” and various enzymes that carry important functions in the onions.

Now that these chemicals are free to mix, they create what is called “propanethiol S-oxide” which is a volatile sulfur gas. This gas floats into our watery lubricated eyes and creates sulfuric acid. Sulfuric acid (H2SO4) is one of the six strong acids of chemistry. Therefore, the sulfuric acid burns, stimulating our eyes to release more tears and to wash away the irritant.

So what can we do to minimize these uncomfortable side-effects?

1. By putting the onions in the freezer 30 minutes before cutting them, you will slow down the activity of the enzymes, therefore reducing the amount of volatile sulfur gas that is created.

2. By cooking the onions in hot water, you will denature the enzymes (inactivate them) and also reduce the amount of volatile sulfur gas that is created.

3. By putting goggles on, the volatile sulfur gas will not come in contact with your eyes, preventing any sulfuric acid from forming on your eyes.

Onion sufferers don’t worry, scientists are breeding a new strain of onions that have decreased levels of harmful enzymes so that tear-inducing onions could become a thing of the past.

What do you guys think? Do you like this? How about a question you would like me to answer for next week’s blog.

Sources Used-

http://chemistry.about.com/od/chemistryfaqs/f/onionscry.htm

http://www.pbs.org/newshour/rundown/2011/02/why-do-onions-make-us-cry.html

http://www.humantouchofchemistry.com/why-onions-make-us-cry.htm

Why Is Yawning Contagious?

Generally, yawning is associated with boredom, tiredness and lack of stimulation. But why is it that when someone in the room yawns, its sets off a chain reaction and many others follow?

Well, scientists have come up with 3 theories to help explain why yawning is contagious. You decide which you like best! 

1. The Evolutionary Theory- Like other animals that yawn (all vertebrates[fish, chimpanzees, dogs. . .]) we yawn to show our teeth, intimidate others and express dominance. So why is yawning contagious? According to this theory, one person yawns after another to subconsciously show their dominance. This theory explains why dogs yawn right before they attack and why olympic athletes usually yawn right before their event. I like this theory because it takes an evolutionary perspective and it takes our instinctual animal behaviors into consideration.

2. The Brain-Cooling Theory- Yawning is the body’s mechanism to cool the brain. In a study done in 2007, participants had cold packs applied to their foreheads while they watched videos of people yawning. The cold packs practically eliminated contagious yawning. According to this theory, yawning decreases brain temperatures which allows for the brain to function more efficiently. So why is yawning contagious? This theory doesn’t really explain why yawning is contagious, but it gives an interesting reason physiologically that may one day be tied to why yawning is contagious. I think this is an interesting study and that more research needs to be done, but according to this theory there is no explanation as to why yawning is contagious.

3. Theory of Empathy- Yawning when others do is a sign of empathy and social bonding. According to a new study, yawning is a shared experience that promotes social bonding. Specifically, yawning diffuses stress after a period of being on high alert and spreads a feeling of calm throughout a group. So why is yawning contagious? According to this theory, those who are no longer on high alert are most likely to yawn after another person because it diffuses any tension and it brings calmness to a group. I like this theory because it makes sense and it really explains why yawning is contagious. Those that are most comfortable with the environment will yawn and those that are still on high alert will not.

How many times did you yawn just by reading this?!?!

What do you guys think? Do you like this? How about a question you would like me to answer for next week’s blog.

Sources Used-

http://well.blogs.nytimes.com/2011/10/03/really-the-claim-yawning-cools-the-brain/

http://tlc.howstuffworks.com/family/question5721.htm

http://news.discovery.com/human/yawning-social-behavior.html