Christmas Eve and ghost stories. Spiders pretend to be ants. Human brain cells into a mouse brain [r/TodayiLearned, Episode #18]


TIL telling ghost stories around a fire was originally a Christmas Eve tradition. Beginning with Charles Dickens’ “A Christmas Carol” it was an annual tradition throughout the Victorian Era and only changed when Halloween became popular in the 1920s.

Though the practice is now more associated with Halloween, spooking out your family is well within the Christmas spirit

For the last hundred years, Americans have kept ghosts in their place, letting them out only in October, in the run-up to our only real haunted holiday, Halloween. But it wasn’t always this way, and it’s no coincidence that the most famous ghost story is a Christmas story—or, put another way, that the most famous Christmas story is a ghost story. Charles Dickens’ A Christmas Carol was first published in 1843, and its story about a man tormented by a series of ghosts the night before Christmas belonged to a once-rich, now mostly forgotten tradition of telling ghost stories on Christmas Eve. Dickens’ supernatural yuletide terror was no outlier since for much of the 19th century, was the holiday indisputably associated with ghosts and the specters.

“Whenever five or six English-speaking people meet round a fire on Christmas Eve, they start telling each other ghost stories,” humorist Jerome K. Jerome wrote in his 1891 collection, Told After Supper. “Nothing satisfies us on Christmas Eve but to hear each other tell authentic anecdotes about specters. It is a genial, festive season, and we love to muse upon graves, and dead bodies, and murders, and blood.”

Telling ghost stories during winter is a hallowed tradition, a folk custom stretches back centuries when families would while away the winter nights with tales of spooks and monsters. “A sad tale’s best for winter,” Mamillius proclaims in Shakespeare’s The Winter’s Tale: “I have one. Of sprites and goblins.” And the titular Jew of Malta in Christopher Marlowe’s play at one point muses, “Now I remember those old women’s words, Who in my wealth would tell me winter’s tales, And speak of spirits and ghosts by night.”


TIL Some spiders disguise themselves as ants by pretending their two front legs are antennae.

All spiders are predators, but most of them are small and have rudimentary defenses against larger animals that in turn prey on them. Spiders have thus evolved a range of predatory behaviors that, at the same time, allow them to evade the threat of predation. Some of the most effective strategies involve deceiving ants.

More than 300 species of spiders are known to mimic the outward appearance of ants, a phenomenon called myrmecomorphy. Aggressively territorial, ants are typically avoided by several predators, thus making them the perfect creatures to impersonate. Most ant-mimicking spiders have a “false waist” and are covered with reflective hairs to simulate the shiny, three-segmented bodies of ants. They have colored patches around their eyes to make their simple eyes look more like an ant’s compound eyes.

The spiders also behave like ants by waving their front pair of legs near their heads like antennae and adopting an erratic zig-zag pattern of movement that is more like ants than spiders.


TIL that Pluto is still a planet in New Mexico since the man who discovered it was from NM.

Do states’ rights include the right to decide what’s a planet, too? When Pluto was recently demoted from planet to “dwarf planet,” it was a blow to the memory of Clyde Tombaugh, who discovered Pluto while working at an observatory in Las Cruces, N.M. The Las Cruces Sun-News says New Mexico is striking back. The state’s House of Representatives voted to declare Pluto a planet whenever it passes over New Mexico.


States’ rights apparently include the right to decide what’s a planet. Astronomers recently demoted Pluto from planet to dwarf planet. That was a blow to the memory of the man who discovered it – Clyde Tombaugh of Las Cruces, New Mexico. His hometown newspaper, the appropriately named Las Cruces Sun-News, says New Mexico is striking back. The State House of Representatives voted that Pluto really is a planet whenever it passes over the state of New Mexico.


TIL that Andrew Jackson was the target of the first attempted presidential assassination, however, when both of the assassin’s guns misfired, Jackson himself attacked the man with his cane. The odds of both fully-functioning weapons misfiring was about 125,000 to 1 according to investigators.

The fiery Jackson had a propensity to respond to aspersions cast on his honor with pistols. Historians estimate that “Old Hickory” may have participated in anywhere between 5 and 100 duels. When a man named Charles Dickinson called Jackson “a worthless scoundrel, a poltroon and a coward” in a local newspaper in 1806, the future president challenged his accuser to a duel. At the command, Dickinson fired and hit Jackson in the chest. The bullet missed Jackson’s heart by barely more than an inch. In spite of the serious wound, Jackson stood his ground, raised his pistol and fired a shot that struck his foe dead. Jackson would carry around the bullet in his chest as well as another from a subsequent duel for the rest of his life.


TIL In 2013, a scientist injected human brain cells into a mouse brain, which improved the mouse’s memory and ability to learn.

A team of neuroscientists has grafted human brain cells into the brains of mice and found that the rodents’ rate of learning and memory far surpassed that of ordinary mice. Remarkably, the cells transplanted were not neurons, but rather types of brain cells, called glia, that are incapable of electrical signaling. The new findings suggest that information processing in the brain extends beyond the mechanism of electrical signaling between neurons.

The experiments were motivated by a desire to understand the functions of glia and test the intriguing possibility that non-electric brain cells could contribute to information processing, cognitive ability, and perhaps even the unparalleled cognitive ability of the human brain, which far exceeds that of any other animal.