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What Causes “Old Person Smell”?

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Reader Sarah writes in to ask, “What is it that causes that distinctive 'old person' smell? Whatever it is, it seems to be common to all elderly people. Is it inevitable or is there something you can do to avoid it?”

Ever notice that your grandparents and their house had a dull, kind of sweet stink to them? You’re not alone. Old people really do have a chemically-distinct odor.

Like other body odors, this “old person smell” is produced when chemicals from the skin glands get broken down into small odorous molecules that waft away into the air. The specific chemical that gives old folks their unique odor, scientists suspect, is a compound called 2-nonenal. Created by the oxidative breakdown of other chemicals over time, it produces what’s described as an “unpleasant greasy and grassy odor” in people and is also responsible for some of the “cardboard” flavor of stale beer.

In 2000, Japanese researchers found that people’s concentration of 2-nonenal increased with age. They had 22 people, ranging in age from 26 to 75, wear odor-collecting shirts to bed for a few nights and then analyzed the molecules that adhered to the cloth. They found more 2-nonenal in the shirts worn by people over 40 years old than they did in the younger subjects. And in the over-40 crowd, the concentration of 2-nonenal increased significantly with age, with the oldest subject producing almost three times as much as the middle-aged subjects. 

The researchers didn’t see any other odor compound increase with age like that, and think that the “deterioration of body odors” in the elderly, as they politely put it, can be pinned on 2-nonenal. But why does the compound increase as a person ages? The researchers also noted the presence of more omega-7 unsaturated fatty acids in the shirts worn by the older subjects, and think that the 2-nonenal comes from the breakdown of these fatty acid chains. The reason the fatty acids increase with age, meanwhile, is still unclear. The researchers speculate that it might be because of age-related changes to metabolism or changes in the amount of some other chemical in skin secretions.

Another big question still hanging in the air is what purpose, if any, an age-related change in smell serves. Humans and some non-human animals can tell the difference between older and younger individuals by smell, and some animals are known to be more attracted to the odor of older individuals and have more success mating as they age. One possible explanation for this is that older individuals may have some genetic advantage that allowed them to survive longer and makes them more attractive mates, and that distinct age-related odor is an advertisement for their genetic quality. It’s not clear that this is what actually happens, but if it is, it’s hard to imagine smell having much of an effect with humans when we place such high value on the physical attractiveness and other qualities of youth.

The fact that old person smell is usually thought of as unpleasant doesn’t seem to be a stumbling block here, though. Research subjects who didn’t know the source of the smell rated old person odors as less intense and less unpleasant than odors from younger people—suggesting that the smell on its own isn’t bad, but is perceived that way in certain contexts.

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Big Questions
Where Should You Place the Apostrophe in President's Day?
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Happy Presidents’ Day! Or is it President’s Day? Or Presidents Day? What you call the national holiday depends on where you are, who you’re honoring, and how you think we’re celebrating.

Saying "President’s Day" infers that the day belongs to a singular president, such as George Washington or Abraham Lincoln, whose birthdays are the basis for the holiday. On the other hand, referring to it as "Presidents’ Day" means that the day belongs to all of the presidents—that it’s their day collectively. Finally, calling the day "Presidents Day"—plural with no apostrophe—would indicate that we’re honoring all POTUSes past and present (yes, even Andrew Johnson), but that no one president actually owns the day.

You would think that in the nearly 140 years since "Washington’s Birthday" was declared a holiday in 1879, someone would have officially declared a way to spell the day. But in fact, even the White House itself hasn’t chosen a single variation for its style guide. They spelled it “President’s Day” here and “Presidents’ Day” here.


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Maybe that indecision comes from the fact that Presidents Day isn’t even a federal holiday. The federal holiday is technically still called “Washington’s Birthday,” and states can choose to call it whatever they want. Some states, like Iowa, don’t officially acknowledge the day at all. And the location of the punctuation mark is a moot point when individual states choose to call it something else entirely, like “George Washington’s Birthday and Daisy Gatson Bates Day” in Arkansas, or “Birthdays of George Washington/Thomas Jefferson” in Alabama. (Alabama loves to split birthday celebrations, by the way; the third Monday in January celebrates both Martin Luther King, Jr., and Robert E. Lee.)

You can look to official grammar sources to declare the right way, but even they don’t agree. The AP Stylebook prefers “Presidents Day,” while Chicago Style uses “Presidents’ Day.”

The bottom line: There’s no rhyme or reason to any of it. Go with what feels right. And even then, if you’re in one of those states that has chosen to spell it “President’s Day”—Washington, for example—and you use one of the grammar book stylings instead, you’re still technically wrong.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Big Questions
How Do You Steer a Bobsled?
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Quinn Rooney, Getty Images

Now that the Olympics are well underway, you might have developed a few questions about the games' equipment. For example: How does one steer a bobsled? Let's take a crack at answering this pressing query.

How do you steer a bobsled?

Bobsled teams careen down an icy, curving track at up to 90 miles per hour, so steering is no small concern. Drivers steer their sleds just like you steered your childhood sleds—by manipulating a pair of ropes connected to the sled's steel runners. The driver also gets help from the rest of the crew members, who shift their weight to aid with the steering.

Why do speed skaters wear glasses?

speed-skating

Speed skaters can fly around the ice at upwards of 40 mph, so those sunglasses-type specs they wear aren't merely ornamental. At such high speeds, it's not very pleasant to have wind blowing in your eyes; it's particularly nightmarish if the breeze is drying out your contact lenses. On top of that, there's all sorts of ice and debris flying around on a speed skating track that could send you on a fast trip to the ophthalmologist.

Some skaters also say the glasses help them see the track. American skater Ryan Bedford recently told the Saginaw News that his tinted shades help him focus on the track and filter out distracting lights and camera flashes from the crowd.

What kind of heat are the biathletes packing?

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As you might guess, there are fairly strict rules governing what sort of rifles biathletes carry on the course. They are equipped with guns chambered for .22 LR ammunition. The gun must weigh at least 3.5 kilograms without its magazines and ammunition, and the rifle has to have a bolt action or a straight-pull bolt rather than firing automatically or semi-automatically.

Is a curling stone really made of stone?

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You bet it is, and it's not just any old stone, either. Curling enthusiasts swear by a very specific type of granite called ailsite that is only found on the Scottish island of Ailsa Craig. Ailsite supposedly absorbs less water than other types of stone, so they last longer than their competitors.

Ailsa Craig is now a wildlife sanctuary, so no new ailsite has been quarried since 2002. As a result, curling stones are incredibly expensive. Kays of Scotland, which has made the stones for every Olympics in which curling has been an official event, gets prices upwards of $1,500 per stone.

What about the brooms?

The earliest curling brooms were actual brooms made of wood with straw heads. Modern brooms, though, are a bit more technologically advanced. The handles are usually made of carbon fiber, and the heads can be made of synthetic materials or natural hair from horses or hogs. Synthetic materials tend to be more common now because they pull all of the debris off of the ice and don't drop the occasional stray bristle like a natural hair broom might.

What are the ski jumpers wearing?

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It may look like a ski jumper can pull on any old form-fitting bodysuit and hit the mountain, but things are a bit more complicated than that. Their suits have to be made of a spongy material and can't be thicker than five millimeters. Additionally, the suits must allow a certain amount of air to pass through them; jumpers wearing suits without sufficient air permeability are disqualified. (This rule keeps jumpers from wearing suits that could unfairly act as airfoils.) These rules are seriously enforced, too; Norwegian skier Sigurd Petterson found himself DQed at the 2006 Torino Games due to improper air permeability.

Those aren't the only concerns, though. In 2010, judges disqualified Italian jumper Roberto Dellasega because his suit was too baggy.

What's up with the short track speed skaters' gloves?

Gloves
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If you watch a bit of short track speed skating, the need for gloves quickly becomes apparent. When the skaters go to make passes or careen around a turn, they need the gloves to keep from cutting their hands due to incidental contact with other skaters' blades.

There's more to the gloves than just safety, though. Since the skaters' hands often touch the ice during turns, they need hard fingertip coverings that won't add friction and slow them down. The tips can be made of any material as long as it's hard and smooth, but you've got to give American skater Apolo Ohno some style points for the gold-tipped left glove he broke out in 2010.

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