What Causes “Old Person Smell”?

iStock / Koldunov
iStock / Koldunov

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.

Turn Your LEGO Bricks Into a Drone With the Flybrix Drone Kit

Flyxbrix/FatBrain
Flyxbrix/FatBrain

Now more than ever, it’s important to have a good hobby. Of course, a lot of people—maybe even you—have been obsessed with learning TikTok dances and baking sourdough bread for the last few months, but those hobbies can wear out their welcome pretty fast. So if you or someone you love is looking for something that’s a little more intellectually stimulating, you need to check out the Flybrix LEGO drone kit from Fat Brain Toys.

What is a Flybrix LEGO Drone Kit?

The Flybrix drone kit lets you build your own drones out of LEGO bricks and fly them around your house using your smartphone as a remote control (via Bluetooth). The kit itself comes with absolutely everything you need to start flying almost immediately, including a bag of 56-plus LEGO bricks, a LEGO figure pilot, eight quick-connect motors, eight propellers, a propeller wrench, a pre-programmed Flybrix flight board PCB, a USB data cord, a LiPo battery, and a USB LiPo battery charger. All you’ll have to do is download the Flybrix Configuration Software, the Bluetooth Flight Control App, and access online instructions and tutorials.

Experiment with your own designs.

The Flybrix LEGO drone kit is specifically designed to promote exploration and experimentation. All the components are tough and can totally withstand a few crash landings, so you can build and rebuild your own drones until you come up with the perfect design. Then you can do it all again. Try different motor arrangements, add your own LEGO bricks, experiment with different shapes—this kit is a wannabe engineer’s dream.

For the more advanced STEM learners out there, Flybrix lets you experiment with coding and block-based coding. It uses an arduino-based hackable circuit board, and the Flybrix app has advanced features that let you try your hand at software design.

Who is the Flybrix LEGO Drone Kit for?

Flybrix is a really fun way to introduce a number of core STEM concepts, which makes it ideal for kids—and technically, that’s who it was designed for. But because engineering and coding can get a little complicated, the recommended age for independent experimentation is 13 and up. However, kids younger than 13 can certainly work on Flybrix drones with the help of their parents. In fact, it actually makes a fantastic family hobby.

Ready to start building your own LEGO drones? Click here to order your Flybrix kit today for $198.

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What Is the Insurrection Act?

The Insurrection Act gives the president the authority to address domestic disturbances using the military.
The Insurrection Act gives the president the authority to address domestic disturbances using the military.
Tero Vesalainen/iStock via Getty Images

The use of military forces to address volatile situations normally under the purview of law enforcement within the United States is a very rare occurrence, and for good reason. Troops are legally forbidden to be involved in domestic law enforcement affairs without prior congressional authorization.

One loophole does exist. It’s the Insurrection Act, and it empowers the president to dispatch soldiers to combat an insurrection, civil disturbance, natural disaster, or terrorist attack on American soil. But actually invoking the Insurrection Act is no simple matter.

The Act was introduced in 1807 and gives the president the authority to direct American troops to intervene in state-level civil unrest in the event local authorities are unable to control the disturbance. (It was amended in 2006 following Hurricane Katrina to include disasters and terrorism.) It’s used sparingly, particularly as modern police forces have become more militarized. The last time the Act was invoked was in 1992, when riots following the acquittal of four police officers tried in the beating of Rodney King consumed Los Angeles.

At the time, the California governor requested military forces—and normally, the president would activate federal troops at the behest of a governor or state legislature. According to the Los Angeles Times, one exception for dispatching soldiers without state approval is an indication that states are violating civil rights, as was the case for several U.S. presidents (Dwight Eisenhower, John F. Kennedy, and Lyndon B. Johnson) who used military forces to back desegregation in Southern states. Alternately, the president would have to believe such events are interfering with a state’s ability to enforce their laws.

Put simply: Military forces are typically sent at the request of the state, but a request isn’t necessary if the president believes troops are needed to restore order.

When states believe local police are being overwhelmed, their preference is to use the National Guard, which is authorized to act as law enforcement on domestic soil.

If the Act is used, the president would first have to issue a proclamation ordering those involved in any disturbance to disperse. If that fails, the president would issue an executive order to activate the military. States would then likely argue against the intrusion of such forces. It is not clear, however, that they would have the legal justification to prevent such an action if the president calls for it.

[h/t Los Angeles Times]