(host) Not many people see the neon '90s fever dream of Lisa Frank, the pure beacons of light in Legend, or the endless barrage of unicorn stuffies and think, "How scary."

Although if you can't unsee a certain "Cabin in the Woods" scene, you know better.

Unicorns are everywhere today.

Take Princess Unikitty, the cat-unicorn hybrid breakout star from "The Lego Movie."

Or Twilight Sparkle, the unicorn who takes command in 2017's "My Little Pony: The Movie."

And of course, there's a seemingly endless supply of stickers, T-shirts, posters, notebooks, board games, plush toys, and action figures.

Unicorns seem to have their own economy.

These days if you combine rainbows and glitter and a horse with a single horn, you will inevitably get a unicorn.

But this is the modern version.

The origins of the unicorn are a little more gory which makes sense given that, typically, a giant horn on an animal's head is a pretty easy way to signal power and frighten predators.

So why is the European unicorn that is so pervasive in popular culture today almost always just a docile, innocent, and magical horse?

[adventurous music] I'm Dr. Emily Zarka, and this is "Monstrum."

A majestic, all-white horse with a spiralized horn on its forehead is the typical unicorn in Western culture today, but this is just one depiction in what were historically many varieties of unicorns.

Take this European paleolithic cave-art painting.

The depiction could be of the very real, but now extinct elasmotherium, a mammoth-sized animal with a single horn in the center of its forehead, but it also might be the original unicorn depiction.

Regardless of the appearance of these monsters in early antiquity, in every story, they are positioned as rare and exotic and incapable of being captured alive which suggests ferocity or preternatural power.

Around 400 BCE, Ctesias writes of a pretty terrifying unicorn he observed in India.

"Wild asses the size of horses "with white bodies, red heads, blue eyes, "and a multicolored horn on their forehead "capable of outrunning any other animal.

"These one-horn creatures can only be killed "when they lead their foals to graze.

"Protective parents, they are unwilling to leave their young vulnerable and stay to defend."

Ctesias emphasizes they are ferocious, even blood-thirsty.

"They will charge hunters, gouging them with their horn "and even cruelly rip up the sides of the hunter's horses with such strength, they're very entrails gush out."

Brutal.

Have I forever changed your perception of unicorns yet?

That's the other thing about unicorns.

Humans have always coveted them because of their unique physiology.

Across history and lore unicorns and their horns were prized for their rarity and assumed supernatural powers.

In reality, the spiralized horns written about in Roman author Claudius Aelianus's third-century encyclopedic account of the world's animals were bought and sold as treasures called alicorns.

Prized by the highest ranking members of society, including the Christian Church and royalty across Europe.

The horns were made into pastoral items and drinking vessels.

They were thought to cure illness and protect anyone who drank from them against poison.

Even serving as an antidote.

That is not the only supernatural attribute of the unicorn.

Aristotle's version of the unicorn is a male goat with a single forehead horn who floats or flies skimming over the whole earth without touching the ground.

Aristotle's language here suggests that all unicorns are male which would become the common assumption.

Other varieties of the unicorn include: a donkey-type sporting and antelope horn, a double-horn variation, and even the sea unicorn, which is arguably the most monstrous.

But to understand the European unicorn's evolution into fantastical symbols of magic and wonder we have to look at Abrahamic scripture.

The holy texts include multiple metaphorical uses of an important horned animal of incredible strength referred to in Hebrew as re'em.

Exactly what kind of animal this creature is referring to is debatable.

Scholars today interpret the original cuneiform symbols, two wedge shapes, as a bull, wild ox, or auroch, implying that the animal has two horns, but original historic interpretations of the cuneiform also include the single-horned rhinoceros and the unicorn.

The unicorn interpretation of the re'em gains popularity only in the Christian faith when the unicorn becomes associated with Christ perpetuating the idea that the unicorn is male gendered.

In around 370 CE Saint Basil warns of a unicorn in his collected homilies on the creation story.

One passage states: "And take heed unto thyself, O man, and beware the unicorn who is the demon."

He goes on to say that the unicorn will gouge and devour men and notes that the great power of this creature compares only with the unconquerable strength of God.

The anonymously authored "Physiologus," a Christian natural history text penned sometime between the second and fourth century, describes the unicorn as "A baby-goat sized, "exceedingly fierce creature that could only be captured using a virgin as bait."

Like Saint Basil's creation homilies, "Physiologus" also connects a fierce unicorn to Christ.

It also includes reference to all the unicorn passages of the Bible, including those that compare the virgin-born Christ being loved like the beloved son of unicorns.

Given the immense popularity of "Physiologus," the unicorn continue to be linked to Christ and now also the Virgin Mary who served as a convenient parallel to the virgin lure folklore already in existence.

The metaphor of Christ as a unicorn was not appreciated by Pope Gelasius.

He declared the connection heretical in 496 but if we know anything about, well, people, that just strengthened the appeal of the unicorn.

The Christian story of Saints Barlaam and Josaphat that appears around the 9 or 10th century features an awfully monstrous unicorn.

Barlaam is teaching Josaphat about the inevitability of death and the unpredictability of the world with a unicorn parable and his isn't the docile unicorn we've come to know today.

According to the story, a man is chased into the jaws of a fire-breathing dragon by a ferocious bellowing unicorn who wishes to devour him.

The man temporarily avoids his fate by hanging onto a tree.

The tale, which became common lore across Western Europe, established the unicorn as a representation of capital D Death.

The unicorn began to appear in narrative fiction of the medieval period, introducing some new traits like a ruby hidden under the horn and adding to some of the established tropes like the virgin lure.

But now the unicorn could detect and kill false virgins.

During the Middle Ages, visual depictions of the unicorn became more uniform in Europe.

Most artwork featured the creature as horse-like with white hair and cloven hooves, moving closer to the unicorn we are most familiar with today.

"The Hunt of the Unicorn," a seven-tapestry series produced around 1500, alternatively called "The Unicorn Tapestries," depicts the hunt of a white-bearded unicorn with a spiraled horn.

The exquisitely-woven textiles show a group of well-dressed men and their hounds chasing down and killing a unicorn after a noblewoman lures the creature into a false sense of security onto her lap.

The final tapestry shows an apparently resurrected captive unicorn.

The red liquid on its flanks may be blood from the hunting wounds that caused its initial demise or perhaps it could be juice dripping from the pomegranates in the tree above which would actually make the unicorn a symbol of fertility according to the fruit's lore.

In my opinion, it is blood from the hunt and this unicorn is undead.

A common interpretation of these tapestries is that the unicorn represents Christ and the events of the hunt are an allegory for his crucifixion.

In another tapestry from around the same time, a series known as "The Lady and the Unicorn," a unicorn appears subservient to a richly-dressed woman.

The image is believed to aid in the tapestry's purpose to depict the tenants of courtly love and decadence in each of the five senses.

They help us understand the unicorn's affinity for virgins, chivalry.

Knights in the Middle Ages lived by strict moral and social codes.

Within these social practices is the idea of courtly love, an idealized expectation of how knights should treat women especially any romantic partner outside of marriage.

The unicorn's metaphor as a symbol of unattainable, unconsumated love first suggested by the virgin subjugation becomes a noble quality.

Unicorns and European heraldry of the time are mostly depicted in silver and white with the body of a horse, the legs of a deer, and a lion's tail.

Scotland's royal coat of arms proudly bears two such chained unicorns.

And when King James united Scotland and England into the United Kingdom in 1603, the new royal crest combined the unicorn with England's lion in a symbol still used by the monarchy today.

The use of the unicorn was a shrewd move by King James.

The version of the Bible he commissioned a year after uniting the crowns contains seven unicorn references including the unicorn as the first animal named by Adam and Eve.

The use of unicorn as the interpretation of re'em not only provided Christian readers a significant holy figure they already recognized, but further solidified the united symbolism of King James's blessed new kingdom as divinely ordained.

Unicorns continued association with rarity and royalty made them a symbol of luxury.

Queen Elizabeth I spent a significant sum to add a unicorn horn to her crown jewels.

King Francis I had one as well, five feet long and decorated with gold.

Even the church treasury of Venice stored two unicorn horns alongside other riches like solid-gold armor and the purported original gospel of Saint Mark.

Alicorn collectors were likely upset when in 1638, Danish zoologist Ole Worm gave a lecture asserting most unicorn horns were in fact, the elongated teeth from narwhals.

In the 17th century belief in unicorns began to decline thanks to science and education.

Europeans at the time believed that finding a unicorn living on their continent was unlikely but the possibility of finding one in some exotic terra incognita was believed plausible through the 19th century.

But as knowledge grows and the exploration of the world continues, the belief in a real unicorn begins to fade.

Beginning in the 20th century, the unicorn monster once said to roam forests and terrorize hunters finds a new home in literature and film as a popular fantasy trope, like the playful pastel colored unicorns of "Fantasia," the unicorn that misses Noah's Ark in Shel Silverstein's 1962 album "Inside Folk Songs" and Peter S. Beagles "The Last Unicorn."

Beagle's book breaks tradition with a female unicorn.

She's on a mission to find out if she is indeed the last of her species.

Along the way, she's temporarily turned into a human woman who romances a prince.

Another twist of the unicorn and maiden legends of the past.

This book illustrates a more contemporary version of the unicorn as a symbol of innocence, magic, and purity.

Lasting associations fortified by popular culture texts, and, of course, backpacks, trapper keepers, and sparkly t-shirts.

It is also in the 20th century that unicorns become the trusted steeds of protagonists like in "Legend," "The Lion, the Witch, and the Wardrobe," and "Stardust."

This metaphorical taming of the unicorn indicates our growing mastery over nature, or at least the illusion of it.

And the killing of a unicorn, once believed to be a great, albeit, near impossible feat, becomes indicative of a character's evil nature.

Because overall, at its core, the unicorn is defined by its rarity.

We've adopted this idea to apply the name unicorn to elusive and highly sought after prizes such as an undervalued startup or polyamorous companion.

Yet part of me wonders if the danger of the unicorn's history is also evoked in these metaphors.

Can there be too much of a good thing?

So outside of a few creative horror movies and imaginative books, the unicorn has gone from terrifying, potentially real monster to religious icon and chivalric symbol, to something entirely different.

But in a way, one thing has remained constant, our desire to commodify the creature.

Possessing a unicorn has always been part of its allure.

If you want to know more about how other cultures around the world have incorporated tales of mythical one-horned creatures as symbols of rarity and resilience, head over to this episode from "Fate & Fabled."

With a unicorn parabel.

Parabel?

"Physiologus," "Physiologus."

Okay.

Given the immense popularity of "Physiologus..." I just said a completely different way, didn't I?