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Why Are Calico Cats Almost Always Female (and Always Look Different)?

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There’s a reason that colorful cats, like tortoiseshells and calicos, tend to be female. It comes down to genetics. 

Females (of all sorts, not just cats) have two X chromosomes, while males have an X and a Y. Rather than being overwhelmed by the double dose of genes provided by having two X chromosomes—each carries more than 1,000 genes—lady organisms have developed something called X-chromosome inactivation, a process that effectively hits the mute button on one of the two X-chromosomes in a cell. 

Kat McGowan explains in Nautilus

On the X chromosome of cats is a skin- and fur-color gene that has two variations (alleles) that dictate either orange fur or black fur. If a female cat inherits one X chromosome with the black allele and one with the orange version, each cell will have both versions, but X-inactivation means that some of her skin cells will code for orange and some for black. The inactivation happens very early in development, when the cat-in-the-making is still just a ball of cells, and the particular nature of skin tissue is that cells and their progeny stay close together. One of those primordial skin progenitor cells that happens to have an active orange allele will give rise to a cohesive blob of millions of cells in the fully developed cat, forming a big orange blotch. The same is true for those coding for black. 

The donor cat (left) and resulting cloned kitten (right, with surrogate mother). Image Credit: Shin et al., Nature (2002)


No calico cat will ever look identical to another. The particular pattern of a multi-colored cat’s coat comes down to chance, meaning that even among the same family, no cat will have the same coloration. Even with the exact same genetic make-up, a calico cat’s coloration would be different than her twin’s because it’s random whether a cell codes for orange or black fur. The same goes for clones. In 2002, when scientists cloned a calico cat named Rainbow, the clone kitten had vastly different coloring from Rainbow, even though their genes were exactly the same. 

Because X-inactivation only happens if there are multiple X chromosomes in one cell, coloration patterns that stem from the process tend to only pop up in female cats. Rarely, a genetic mutation can result in a cat being born with an extra chromosome (XXY), leading to a male calico or tortoiseshell cat, but for the most part, it’s purely a ladies’ club. 

[h/t: Nautilus]

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holidays
What Are the 12 Days of Christmas?
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Everyone knows to expect a partridge in a pear tree from your true love on the first day of Christmas ... But when is the first day of Christmas?

You'd think that the 12 days of Christmas would lead up to the big day—that's how countdowns work, as any year-end list would illustrate—but in Western Christianity, "Christmas" actually begins on December 25th and ends on January 5th. According to liturgy, the 12 days signify the time in between the birth of Christ and the night before Epiphany, which is the day the Magi visited bearing gifts. This is also called "Twelfth Night." (Epiphany is marked in most Western Christian traditions as happening on January 6th, and in some countries, the 12 days begin on December 26th.)

As for the ubiquitous song, it is said to be French in origin and was first printed in England in 1780. Rumors spread that it was a coded guide for Catholics who had to study their faith in secret in 16th-century England when Catholicism was against the law. According to the Christian Resource Institute, the legend is that "The 'true love' mentioned in the song is not an earthly suitor, but refers to God Himself. The 'me' who receives the presents refers to every baptized person who is part of the Christian Faith. Each of the 'days' represents some aspect of the Christian Faith that was important for children to learn."

In debunking that story, Snopes excerpted a 1998 email that lists what each object in the song supposedly symbolizes:

2 Turtle Doves = the Old and New Testaments
3 French Hens = Faith, Hope and Charity, the Theological Virtues
4 Calling Birds = the Four Gospels and/or the Four Evangelists
5 Golden Rings = the first Five Books of the Old Testament, the "Pentateuch", which gives the history of man's fall from grace.
6 Geese A-laying = the six days of creation
7 Swans A-swimming = the seven gifts of the Holy Spirit, the seven sacraments
8 Maids A-milking = the eight beatitudes
9 Ladies Dancing = the nine Fruits of the Holy Spirit
10 Lords A-leaping = the ten commandments
11 Pipers Piping = the eleven faithful apostles
12 Drummers Drumming = the twelve points of doctrine in the Apostle's Creed

There is pretty much no historical evidence pointing to the song's secret history, although the arguments for the legend are compelling. In all likelihood, the song's "code" was invented retroactively.

Hidden meaning or not, one thing is definitely certain: You have "The Twelve Days of Christmas" stuck in your head right now.

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Big Questions
Where Does the Phrase '… And the Horse You Rode In On' Come From?
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Horses may no longer be the dominant form of transportation in the U.S., but the legacy of our horseback-riding history lives on in language. When telling people off, we still use the phrase “... and the horse you rode in on.” These days, it’s rare for anyone you're telling to go screw themselves to actually be an equestrian, so where did “and the horse you rode in on” come from, anyway?

Well, let’s start with the basics. The phrase is, essentially, an intensifier, one typically appended to the phrase “F*** you.” As the public radio show "A Way With Words" puts it, it’s usually aimed at “someone who’s full of himself and unwelcome to boot.” As co-host and lexicographer Grant Barrett explains, “instead of just insulting you, they want to insult your whole circumstance.”

The phrase can be traced back to at least the 1950s, but it may be even older than that, since, as Barrett notes, plenty of crude language didn’t make it into print in the early 20th century. He suggests that it could have been in wide use even prior to World War II.

In 1998, William Safire of The New York Times tracked down several novels that employed the term, including The Friends of Eddie Coyle (1972) and No Bugles, No Drums (1976). The literary editor of the latter book, Michael Seidman, told Safire that he heard the term growing up in the Bronx just after the Korean War, leading the journalist to peg the origin of the phrase to at least the late 1950s.

The phrase has had some pretty die-hard fans over the years, too. Donald Regan, who was Secretary of the Treasury under Ronald Reagan from 1981 through 1984, worked it into his official Treasury Department portrait. You can see a title along the spine of a book in the background of the painting. It reads: “And the Horse You Rode In On,” apparently one of Regan’s favorite sayings. (The book in the painting didn't refer to a real book, but there have since been a few published that bear similar names, like Clinton strategist James Carville’s book …and the Horse He Rode In On: The People V. Kenneth Starr and Dakota McFadzean’s 2013 book of comics Other Stories And the Horse You Rode In On.)

It seems that even in a world where almost no one rides in on a horse, insulting a man’s steed is a timeless burn.

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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