Why Do Itches Itch?


We’re not talking about itches from bug bites or poison ivy, which are reactions to histamine. We mean those random itches that leave you absent-mindedly scratching your nose.

Itch research remains a relatively new field of study, and, previously, itches were thought to be just extremely mild forms of pain. While both itches and pain (and heat) are all transmitted through the body by similar neurons, a 2013 study showed that itches are special—they’re triggered by Nppb, a neurotransmitter that also happens to be responsible for controlling blood pressure. Without Nppb, you wouldn’t feel itchy.

Gil Yosipovitch, M.D., director of the Temple Itch Center, explains that itches evolved to warn animals of environmental dangers. Receptors near the skin’s surface are poised to react to any external irritant, no matter how tiny. If you feel a random itch, something just a couple microns long—be it dust, soap residue, dead skin, or a thread of clothing—is probably disturbing a few nerve endings, which send signals to the spinal cord asking for a much-needed scratch.

Why Are There No Snakes in Ireland?


Legend tells of St. Patrick using the power of his faith to drive all of Ireland’s snakes into the sea. It’s an impressive image, but there’s no way it could have happened.

There never were any snakes in Ireland, partly for the same reason that there are no snakes in Hawaii, Iceland, New Zealand, Greenland, or Antarctica: the Emerald Isle is, well, an island.

Eightofnine via Wikimedia Commons // Public Domain

Once upon a time, Ireland was connected to a larger landmass. But that time was an ice age that kept the land far too chilly for cold-blooded reptiles. As the ice age ended around 10,000 years ago, glaciers melted, pouring even more cold water into the now-impassable expanse between Ireland and its neighbors.

Other animals, like wild boars, lynx, and brown bears, managed to make it across—as did a single reptile: the common lizard. Snakes, however, missed their chance.

The country’s serpent-free reputation has, somewhat perversely, turned snake ownership into a status symbol. There have been numerous reports of large pet snakes escaping or being released. As of yet, no species has managed to take hold in the wild—a small miracle in itself.

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If March 15 Is the Ides of March, What Does That Make March 16?


Everyone knows that the soothsayer in William Shakespeare's Julius Caesar was talking about March 15 when he warned the Roman emperor to "beware the Ides of March." We also all know Caesar's response: "Nah, I gotta head into the office that day." But if March 15 is the Ides of March, what does that make March 16?

At the time of Caesar's assassination, Romans were using the Julian calendar (introduced by Julius Caesar himself). This was a modified version of the original Roman calendar, and it is very similar to the one we use today (which is called the Gregorian calendar). A major difference, however, was how Romans talked about the days.

Each month had three important dates: the Kalends (first day of the month), the Ides (the middle of the month), and the Nones (ninth day before the Ides, which corresponded with the first phase of the Moon). Instead of counting up (i.e., March 10, March 11, March 12), Romans kept track by counting backwards and inclusively from the Kalends, Ides, or Nones. March 10 was the sixth day before the Ides of March, March 11 was the fifth day before the Ides of March, and so on.

Because it came after the Ides, March 16 would’ve been referred to in the context of April: "The 17th day before the Kalends of April." The abbreviated form of this was a.d. XVII Kal. Apr., with "a.d." standing for ante diem, meaning roughly "the day before."

So, had Julius Caesar been murdered on March 16, the soothsayer's ominous warning would have been, "Beware the 17th day before the Kalends of April." Doesn't have quite the same ring to it.

This story first ran in 2016.