Why Do I Sometimes Scratch One Body Part and Feel It on Another?

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iStock

Ever scratch an itch on your stomach and feel the scratch on your elbow? Or scratch your leg and feel a prickly sensation on your neck? You’re not alone. Lots of people report feeling a sensation from a scratch in places far from where they’re scratching, including scratches on the ear that produce tickles in the throat and mixed signals between their thumb and their tongue.

It’s one of those delightfully weird things your body does, and it’s been studied, albeit infrequently, for hundreds of years. English clergyman and scientist Stephen Hales first described the phenomenon in the 1730s, referring to it as “instances of the sympathy of the nerves.” About a century later, physiologist Johannes Muller came along and applied one of those cool words to it that the Germans are really good at coming up with: mitempfindungen. Since then, we’ve just called it “referred itch” in English.

For most people, referred itch is just a weird annoyance. It doesn’t do any damage or have any ill effects, and so it doesn’t get a whole lot of research attention. Scientists haven’t even been able to nail down how common it is. One study found that it only happens in 10 percent of the population. Another said 20 percent. Still others put the figure at anywhere between 50 and 90 percent of people.

How and why it happens is anybody’s guess, but scientists have a handful of hypotheses to explain what’s going on. One idea is that referred itch is the product of our complex system of nerves being “rather irregularly distributed” throughout the body. British physician Phillip Evans wrote in the 1970s that it was difficult for him to envision “such a diffuse system providing sensations that are so clearly imagined to be in small and easily localized areas of skin.” In other words, in our haphazard map of nerves, some sensations are bound to be confused.

Another explanation in a similar vein is that some branches of a nerve may travel out in a much different path than the others and wind up in some far-flung part of the body. Again, the nervous system gets a little confused and a sensation at one end of a branch might feel like it's coming from another.

It could also be that the mix up isn’t in the nerves, but the brain. In the parts of the brain that deal with our sense of touch, regions that receive and process information from different parts of the body overlap. “Hand and shoulder areas … overlap the trunk area, and the area for the thumb overlaps that for the upper part of the tongue,” Evans wrote. “There is so much overlapping that it is difficult to see how referred itches arising from different parts of the body can be coherently separated in the cortex.”

Finally, for some people, chronic referred itches could happen in parts of the body “rendered abnormal by damage to the nervous system.”

Are Any of the Scientific Instruments Left on the Moon By the Apollo Astronauts Still Functional?

Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Apollo 11 astronaut Neil Armstrong left the first footprint on the Moon on July 20, 1969.
Heritage Space/Heritage Images/Getty Images

C Stuart Hardwick:

The retroreflectors left as part of the Apollo Lunar Ranging Experiment are still fully functional, though their reflective efficiency has diminished over the years.

This deterioration is actually now delivering valuable data. The deterioration has multiple causes including micrometeorite impacts and dust deposition on the reflector surface, and chemical degradation of the mirror surface on the underside—among other things.

As technology has advanced, ground station sensitivity has been repeatedly upgraded faster than the reflectors have deteriorated. As a result, measurements have gotten better, not worse, and measurements of the degradation itself have, among other things, lent support to the idea that static electric charge gives the moon an ephemeral periodic near-surface pseudo-atmosphere of electrically levitating dust.

No other Apollo experiments on the moon remain functional. All the missions except the first included experiment packages powered by radiothermoelectric generators (RTGs), which operated until they were ordered to shut down on September 30, 1977. This was done to save money, but also because by then the RTGs could no longer power the transmitters or any instruments, and the control room used to maintain contact was needed for other purposes.

Because of fears that some problem might force Apollo 11 to abort back to orbit soon after landing, Apollo 11 deployed a simplified experiment package including a solar-powered seismometer which failed after 21 days.

This post originally appeared on Quora. Click here to view.

What Makes a Hotel Breakfast 'Continental'?

Hotels often offer a complimentary pastry and fruit breakfast.
Hotels often offer a complimentary pastry and fruit breakfast.
tashka2000/iStock via Getty Images

The continental breakfast, which is typically made up of pastries, fruit, and coffee, is often advertised by hotels as a free perk for guests. But why is it called continental, and why don’t patrons get some eggs and bacon along with it?

The term dates back to 19th century Britain, where residents referred to mainland Europe as “the continent.” Breakfast in this region was usually something light, whereas an English or American breakfast incorporated meat, beans, and other “heavy” menu options.

American hotels that wanted to appeal to European travelers began advertising “continental breakfasts” as a kind of flashing neon sign to indicate guests wouldn’t be limited to American breakfast fare that they found unappealing. The strategy was ideal for hotels, which saved money by offering some muffins, fruit, and coffee and calling it a day.

That affordability as well as convenience—pastries and fruit are shelf-stable, requiring no heat or refrigeration to maintain food safety—is a big reason continental breakfasts have endured. It’s also a carryover from the hybrid model of hotel pricing, where American hotels typically folded the cost of meals into one bill and European hotels billed for food separately. By offering a continental breakfast, guests got the best of both worlds. And while Americans were initially aghast at the lack of sausages and pancakes on offer, they’ve since come around to the appeal of a muffin and some orange juice to get their travel day started.

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