Boxers, briefs, trunks, tighty-whities.

Although some refer to underwear as "unmentionables," today, I'll be mentioning them... a lot, because men's underwear actually has a fascinating history that goes beyond its practical uses of protection, cleanliness, and modesty.

Alan Greenspan, the chair of the U.S. Federal Reserve from 1987 to 2006, suggested in an interview with National Public Radio that the underwear industry is actually an indicator of U.S. economic health because the purchase of underwear is somehow "discretionary"-- a very debatable term.

The idea that you can track underwear sales to economic growth actually has a name: the Men's Underwear Index, or MUI.

Men's underwear styles and sales are also an important cultural indicator, a way of tracking how fashion, mores, and the idea of what it means to present oneself as masculine have changed over time.

Today, we're going "behind the belt" to investigate how the shape of men's underwear in Western Europe and the U.S. provides insight into both the economy as well as changing notions of masculinity.

[upbeat music] Before we get to the "bottom" of the topic at hand, a "brief" nod to the first known covering of the male genitalia, the loincloth, a simple piece of cloth or leather wrapped around the hips and groin.

Versions of the loincloth were developed in diverse cultures, ranging from ancient Europe, Asia, Africa, and the Americas.

The primary function of these garments was to protect the genitals from the sun, the elements, and impact.

Our study of underwear as a more stylish garment that was generally worn underneath other clothing, however, actually begins in 12th century Europe, when men shifted from wearing breaches on the outside to wearing them beneath long tunics.

As historian Shaun Cole reports, over the next couple hundred years, breaches became shorter and tighter, and the waistline was lowered from above the stomach to the hips.

In medieval Europe, wearing breaches was a signifier of morality.

Not only was it thought to be more hygienic to have a layer between genitals and outer clothing, but also disguising the shape of the genitals was believed to promote modesty and chastity.

At the end of the 14th century, men's undergarments appeared outside again as a way to assert power.

Enter the codpiece.

Originally, the codpiece was simply a flap that covered the relevant areas.

It would be attached to the hose and a short jacket, and allowed men to urinate without removing their pants.

The codpiece could be lightly padded or made out of leather to offer protection.

Over time, codpieces became increasingly decorative, and, well, increasingly... increased.

Cole argues that the large codpiece was not meant to offer a sexual invitation to women.

Instead, it served as what he calls "an aggressive "and eye-catching warning to men.

"Its importance was concerned with social, temporal, "and territorial power, rather than just sexual prowess."

Codpieces eventually went out of fashion.

Historian Victoria Bartels explains that many costume historians believe that it went out of style due to more feminine looks that came into vogue in the French and English courts.

Whatever the reason, by the 17th century, men were replacing the hose that ran up to the codpiece with an outer legging, which they wore over a set of drawers or lining tied below the knee and at the waist.

The ability to afford such garments was, again, a sign of the largeness of one's... purse.

[Danielle laughing] (cameraperson) Great.

Sorry.

(cameraperson) That was good.

[Danielle laughing] Okay, I'm five.

18th and 19th century technological breakthroughs brought underwear to the masses.

In the late 18th century, a material that was less likely to shrink, made out of cotton and wool, was manufactured.

This was ideal for constructing garments that needed to be washed many, many times in hot water.

In the 19th century, the arrival of the sewing machine made it more efficient and cheaper to construct clothes.

Although manufactured underwear was still a "discretionary purchase," the lowered price point made it more accessible to the masses.

Presumably, in this era, the Men's Underwear Index was on an uptick.

Despite the invention of a form of elastic that could be sewn into clothes, helping to keep them where they belong, 19th century underwear was still bulky and uncomfortable.

In 1868, a patent was issued in America for ladies undergarments that united an undershirt to a pair of drawers called a "union suit," which some referred to as "emancipation union under flannel," although I think that would be a better tagline for the birthday suit.

It allowed more freedom of movement than afforded by multi-piece undergarments.

The men's version of the union suit became popular on the frontier.

They became a scratchy and not particularly aesthetic signifier attached to the myth of a rugged American masculinity.

If notions of masculinity were tied to the myth of dominating the frontier, they were also connected to athleticism.

At the end of the 19th century, bicycle jockeys delivered packages around cities paved with bumpy cobblestone streets.

In the last couple of decades of the 19th century, a Chicago-based sporting goods store patented an athletic supporter for these riders called, you guessed it, the jockstrap.

Sears, Roebuck mass marketed jockstraps in their catalogs.

By the start of the 20th century, jockstraps were incorporated into team uniforms.

At the same time, the union suit was reinvented for athletes.

In 1914, BVD sold a sleeveless version of the suit with shorter legs and made out of lightweight cotton.

According to legend, after the heavyweight boxer Jack Dempsey won the 1919 world title, Everlast began to market a long and loose style of underwear called "boxer shorts."

Even though briefs were introduced as useful to exercise at the start of the century in France, they didn't catch on in America until much later.

Although American manhood was often associated with domineering, pugilistic, and athletic qualities, in the 1920s, some were incorporating more traits associated with ideas of the feminine into men's clothing.

According to fashion historian Daniel Delis Hill, a 1925 edition of Menswear reads, "Despite the alarm for many men that athletic underwear "in pink, pale blue, peach, blazer stripes, "et cetera, has a feminine look about it, "such designs became widely available "from mass merchandisers like Sears and Montgomery Ward."

It's interesting that pink, blue, and stripes were all lumped under the umbrella of feminine attire.

Much as men's underwear became more colorful, it also became softer, due to declining silk prices and the mass production of rayon in the 1920s.

Soon, this decorative undie trend spread to appreciating the masculine form itself.

In the 1930s, a Wisconsin company called Coopers introduced the jockey Y-cut brief.

According to an ad, "Jockeys are snug and brief, "molded to your muscles.

"Built-in masculine support made "of lightweight, porous, absorbent knitted fabric "with the famous Y-front, no-gap front opening."

When a Chicago Marshall Field's store displayed a jockey-clad mannequin in their windows, it caused a sensation-- 30,000 pairs were sold within three months.

Coopers renamed their company "Jockey," and even hired a plane called the Mascul-liner to deliver briefs across America.

Scholars Martin and Harold Koda offer an important insight.

The 1935 launch of the jockey short coincides with the era that American beaches began to allow men to go topless.

"The erotics of the male were undergoing change," they write, which represents "a sea change in concepts of masculinity."

This exuberance about the male form was tempered somewhat by World War II.

Rubber was rationed, and many manufacturers reverted to earlier ways of fastening underwear.

In the Army, soldiers were issued olive drab cotton briefs and long johns.

The infamous "undies" got their name from champion heavyweight boxer John L. Sullivan, reinforcing the connection between idealized masculine athleticism and underoos.

Hill argues that World War II gas rationing caused the long john to also have a resurgence on the home front.

But this tempering did not last for long.

After the war, the American economy was booming.

People had more money in their pockets, and there was demand for novelty, even in men's underwear, which is the thing underneath those fat-filled pockets.

This meant new fabrics, shapes, and patterns.

Manufacturers such as Sears and Montgomery Ward began selling men's underwear with prints on it, which may denote a more playful attitude towards the male body.

During the 1950s and 1960s, men's pants were being cut more tightly, including marketing of bikinis to American men by familiar companies, including Jockey.

In the 1970s, men's underwear branched out to include more extreme forms, culminating in 1982 when Calvin Klein made some of these designs mainstream, as it launched a line that included thongs and G-strings for the fellas.

Calvin Klein also placed visible branding on the waistband of its underwear.

The desire to show off the brand of one's underwear may be one factor contributing to the trend of sagging or exposing one's underwear above low-hung jeans.

This trend, first made popular by 1990s hip-hop artists, was viewed as a general desire to thwart authority and reject mainstream values.

It is an assertion of rebellion, and as such, is completely at one with the domineering, pugilistic, and athletic vision of American masculinity behind earlier underwear trends.

There is also a strain of puritanical modesty in American masculine culture.

Enter the enormously popular boxer brief, which appeared in the early '90s.

The boxer brief is an updated version of the Victorian knit underwear.

It provides the support of a brief combined with the coverage of a boxer without all of that annoying bunching.

These essentially conservative garments are available in a wide variety of colors and materials.

As such, they offer a relatively safe space for personal expression.

But don't be fooled.

These are a rather tight garment designed to draw attention to conventional male anatomy.

Consider the boxer briefs included in Duluth Trading Company's "Buck Naked" underwear brand, a line which the company describes as "no pinch, no stink, no sweat," and markets as being like "wearing nothing at all."

Because what's more modest than going commando?

These fashions suggest American men have become increasingly comfortable with the idea that their bodies are sexually desirable, and new shape-reducing options suggest that some associate thinness with allure.

So, although the ties between men's underwear designs and changing ideals of masculinity have been as stubbornly stuck together as the worst wedgie for hundreds of years, by the late 20th century, the tides were changing to include more expressive and playful designs.

And today, these discretionary unmentionables are bucking the norms even more than ever before.