Why Do Onions Make You Cry?

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The onion has been traced back as far as the Bronze Age and was worshipped by the Ancient Egyptians (and eaten by the Israelites during their bondage in Egypt). Onions were rubbed over the muscles of Roman gladiators, used to pay rent in the Middle Ages, and eventually brought to the Americas, where today we fry, caramelize, pickle, grill, and generally enjoy them.

Many of us burst into tears when we cut into one, too. It's the price we pay for onion-y goodness. Here's a play-by-play breakdown of how we go from grabbing a knife to crying like a baby:

1. When you cut into an onion, its ruptured cells release all sorts of goodies, like allinase enzymes and amino acid sulfoxides. The former breaks the latter down into sulfenic acids.

2. The sulfenic acids, unstable bunch that they are, spontaneously rearrange into thiosulfinates, which produce a pungent odor and at one time got the blame for our tears. The acids are also converted by the LF-synthase enzyme into a gas called syn-propanethial-S-oxide, also known as the lachrymatory factor (or the crying factor).

3. Syn-propanethial-S-oxide moves through the air and reaches our eyes. The first part of the eye it meets, the cornea, is populated by autonomic motor fibers that lead to the lachrymal glands. When syn-propanethial-S-oxide is detected, all the fibers in the cornea start firing and tell the lachrymal glands to wash the irritant away.

4. Our eyes automatically start blinking and producing tears, which flushes the irritant away. Of course, our reaction to burning eyes is often to rub them, which only makes things worse since our hands also have some syn-propanethial-S-oxide on them.

It only takes about 30 seconds to start crying after you make the first cut; that's the time needed for syn-propanethial-S-oxide formation to peak.

WHY DON'T GREEN ONIONS MAKE US CRY?

The onion's relatives, like green onions, shallots, leeks and garlic, also produce sulfenic acids when cut, but they generally have fewer (or no) LF-synthase enzymes and don't produce syn-propanethial-S-oxide.

HOW DO I AVOID CRYING?

Since I usually go through a good deal of onions while cooking at home, I've been road testing some of the different methods the internet suggests for reducing or avoiding the effects of the lachrymatory factor. Here's what I tried:

Method #1: Chill or slightly freeze the onions before cutting, the idea being that this will change the chemical reactions and reduce the gas that is released.
Result: The onion from the fridge has me crying just as quickly as room temperature ones. The one that was in a freezer for 30 minutes leaves me dry-eyed for a bit, but by the time I'm done dicing my eyes start to burn a little.

Method #2: Cut fast! Get the chopping over with before the gas reaches your eyes.
Result: Just hacking away at the onion, I get in the frying pan without so much as a sting in my eyes. The onion looks awful, though. Doing a proper dice, I take a little too long and start tearing up. If you don't mind a mangled onion, this is the way to go.

Method #3: Put a slice of bread in your mouth, and cut the onion with most of the bread sticking out to "catch" the fumes.
Result: It seems the loaf of bread I have has gone stale. I stop the experiment and put bread on my shopping list.

Method #4: Chew gum while chopping. It keeps you breathing through your mouth, which keeps the fumes away from your eyes.
Result: This seems to work pretty well as long as you hold your head in the right position. Leaning toward the cutting board or looking right down at the onion puts your eyes right in the line of fire again.

Method #5: Cut the onions under running water. This prevents the gas from traveling up into the eyes.
Result: An onion in the sink is a hard onion to cut. I think Confucius said that. My leaky Brita filter is spraying me in the face and I'm terrified I'm going to cut myself, but I'm certainly not crying.

Method #6: Wear goggles.
Result: In an effort to maintain my dignity, I try my eyeglasses and sunglasses first. Neither do me any good. The ol' chemistry lab safety glasses make me look silly, but help a little more. I imagine swim goggles would really do the trick, but I don't have any.

Method #7: Change your onion. "Tear free" onions have been developed in the UK via special breeding and in New Zealand via "gene silencing" techniques.
Result: My nearest grocery store, Whole Foods, doesn't sell genetically modified produce or onions from England. Tonight, we eat leeks!

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What's the Difference Between Pigeons and Doves?

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To the layman, the difference between pigeons and doves has something to with color, maybe. Or location. Or general appeal (doves usually get much better press than pigeons do). But what’s the actual, scientific difference between doves and pigeons?

As it turns out, there isn’t one. Paul Sweet, the collection manager for the department of ornithology at the American Museum of Natural History, says the difference is more linguistic than taxonomic.

“The word dove is a word that came into English from the more Nordic languages, whereas pigeon came into English from French,” Sweet tells Mental Floss.

Both dove and pigeon refer to the 308 species of birds from the Columbidae family, Sweet says. There’s no difference between a pigeon and a dove in scientific nomenclature, but colloquial English tends to categorize them by size. Something called a dove is generally smaller than something called a pigeon, but that’s not always the case. A common pigeon, for example, is called both a rock dove and a rock pigeon.

“People just have their own classification for what makes them different,” Sweet says. “So in the Pacific, for example, the big ones might get called pigeons and the smaller ones might be called doves, but they’re actually more closely related to each other than they are to other things in, say, South America, that are called pigeons and doves.”

The difference boils down to linguistic traditions, so feel free to tell people you’re releasing pigeons at your wedding or that you’re feeding doves in the park. Scientifically speaking, you’ll be correct either way.

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What Is the Wilhelm Scream?

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What do Star Wars, The Lord of the Rings, Pirates of the Caribbean, Harold and Kumar Go to White Castle, Toy Story, Reservoir Dogs, Titanic, Anchorman, 22 Jump Street, and more than 200 other films and TV shows have in common? Not much besides the one and only Wilhelm Scream.

The Wilhelm Scream is the holy grail of movie geek sound effects—a throwaway sound bite with inauspicious beginnings that was turned into the best movie in-joke ever when it was revived in the 1970s.

Just what is it? Chances are you’ve heard it before but never really noticed it. The Wilhelm Scream is a stock sound effect that has been used in both the biggest blockbusters and the lowest low-budget movies and television shows for over 60 years, and is usually heard when someone onscreen is shot or falls from a great height.

First used in the 1951 Gary Cooper western Distant Drums, the distinctive yelp began in a scene in which a group of soldiers wade through a swamp, and one of them lets out a piercing scream as an alligator drags him underwater.

As is the case with many movie sound effects, the scream was recorded later in a sound booth with the simple direction to make it sound like “a man getting bit by an alligator, and he screams.” Six screams were performed in one take, and the fifth scream on the recording became the iconic Wilhelm (the others were used for additional screams in other parts of the movie).

Following its debut in 1951, the effect became a regular part of the Warner Bros. sound library and was continually used by the studio’s filmmakers in their movies. Eventually, in the early 1970s, a group of budding sound designers at USC’s film school—including future Academy Award-winning sound designer Ben Burtt—recognized that the unique scream kept popping up in numerous films they were watching. They nicknamed it the “Wilhelm Scream” after a character in the first movie they all recognized it from, a 1963 western called The Charge at Feather River, in which a character named Private Wilhelm lets out the pained scream after being shot in the leg by an arrow.

As a joke, the students began slipping the effect into the student films they were working on at the time. After he graduated, Burtt was tapped by fellow USC alum George Lucas to do the sound design on a little film he was making called Star Wars. As a nod to his friends, Burtt put the original sound effect from the Warner Bros. library into the movie, most noticeably when a Stormtrooper is shot by Luke Skywalker and falls into a chasm on the Death Star. Burtt would go on to use the Wilhelm Scream in various scenes in every Star Wars and Indiana Jones movie, causing fans and filmmakers to take notice.

Directors like Peter Jackson and Quentin Tarantino, as well as countless other sound designers, sought out the sound and put it in their movies as a humorous nod to Burtt. They wanted to be in on the joke too, and the Wilhelm Scream began showing up everywhere, making it an unofficial badge of honor. It's become bigger than just a sound effect, and the name “Wilhelm Scream” has been used for everything from a band name, to a beer, to a song title, and more.

But whose voice does the scream itself belong to? Burtt himself did copious amounts of research, as the identity of the screamer was unknown for decades. He eventually found a Warner Bros. call sheet from Distant Drums that listed actors who were scheduled to record additional dialogue after the film was completed. One of the names, and the most likely candidate as the Wilhelm screamer, was an actor and musician named Sheb Wooley, who appeared in classics like High Noon, Giant, and the TV show Rawhide. You may also know him as the musician who sang the popular 1958 novelty song “Purple People Eater.”

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