Dave Roos

Contributing Writer

Dave is a freelance journalist who has contributed hundreds of articles to HowStuffWorks since 2007, with a specialty in personal finance, economics and business. Raised in Pittsburgh, Pennsylvania, he attended Duke University where he earned the B.A. in comparative religious studies that has served him so well.

Dave began freelancing when he and his wife moved to Mexico in 2003, publishing articles about Mexican food and culture in The New York Times, the Los Angeles Times and Newsweek. Nearly 15 years and three kids later, Dave and his family recently moved back to Mexico and just might stay a while.

Recent Contributions

Meet the Trebuchet, the Castle-crushing Catapult of the Middle Ages

Before the advent of gunpowder, enemy combatants used a powerful siege weapon called a trebuchet to forcefully launch projectiles — sometimes a large stone, a decapitated human head or a dead horse — at intended targets.

How Does Kaizen Differ from Lean and Six Sigma?

The Kaizen philosophy of continuous improvement has been adopted by many big companies around the world. So, how did it start and how does it differ from Six Sigma?

Why Is the U.S. Experiencing a Coin Shortage?

Now that America seems to be getting over the great toilet paper shortage, the next thing in short supply is coins. But why?

Against Crazy Odds, Simon Bolivar Liberated Six Countries in South America

Bolívar was the catalyst and cult of personality behind the 19th-century liberation movement that won independence for six Latin American nations: Venezuela, Colombia, Ecuador, Panama, Peru and Bolivia, a country named for the Liberator himself.

7 Puritan Myths We Should Stop Believing

We often think of Puritans as those pilgrims to America whose twin passions were long church services and burning witches. But the truth is far more interesting.

From William the Bastard to William the Conqueror: The King Who Transformed England

This brilliant, ruthless leader invaded England in 1066 and utterly changed the course of British history. In fact, he is the 'father' of every British monarch since.

Why Did Hitler Write 'Mein Kampf'?

In 1925, Adolf Hitler published the first volume of a semi-autobiographical book that laid out his racist policies. It is still in print today. But should anyone read it? And what would they find inside?

Did King Nebuchadnezzar Really Go Mad and Eat Grass for 7 Years?

The Bible says that God caused Nebuchadnezzar to become insane and live like an animal for seven years as punishment for his arrogance. But is there any historical evidence for this?

The Angel of Death Has One Job, and He Does It Well

In TV shows and movies, sometimes an angel of death appears to tell some unfortunate soul their time on Earth is over. But where did this idea come from? And what if you tell the angel, "I'm not ready?"

Amerigo Vespucci, a Lurid Pamphlet and the Naming of America

It pays to promote. That's how Amerigo Vespucci got a new continent named in his honor. That and a little historical misunderstanding.

Slavery Under Another Name: What Were the Black Codes?

The Emancipation Proclamation may have signified the formal end of slavery. But almost immediately afterward, Southern states enacted Black Codes that effectively re-enslaved thousands of newly freed Black people.

How Gin Works

In the 18th century, gin was considered as addictive as crack. Then it became part of a cure-all for tropical ailments. Oh, and let's not forget its starring role in Prohibition. Bathtub gin, anyone?

Why the 'Streisand Effect' Might Actually Make a Cover-up Go Viral

When Barbra Streisand sued a photographer who took a photo of her house, the ensuing publicity called far more attention to the picture than it would have gotten otherwise. And that's not the only time attempted censorship has backfired.

Call it Arroba, Kukac or Strudel: The History of the @ Sign

The @ sign is so much a part of the internet that it may surprise you to know it's been around for at least 1,500 years.

Voltaire Was an Enlightenment Celebrity Who Would've Loved Social Media

Before there was a Madonna, Bono or Beyoncé, the one-named Voltaire was Europe's first truly modern celebrity. And he didn't need the help of Twitter to keep his name in the public eye.

When Presidential Approval Ratings Really Matter

Every week there's a poll with new numbers on how many Americans approve of the president's job performance. But what do these numbers really tell us and when should we take them seriously?

10 Big Questions About Hinduism, Answered

Are Hindus polytheistic? Do they worship cows? And how does yoga fit into this religion? We answer some of the most-asked questions around Hinduism.

5 Fascinating Stories of Abolitionists Past and Present

One was a former slave, turned best-selling writer; another was a wealthy pottery maker whose company is well-known even today. Here are five amazing stories of abolitionists.

What Does Zionism Really Mean?

Although Zionism draws its name from the biblical Mount Zion, it is primarily a secular, rather than religious movement. So, what does it mean, and why do some people find it controversial?

Why Marcus Aurelius Matters, in 5 of His Classic Quotes

Roman emperor Marcus Aurelius is remembered today, not so much for his conquests and governance but for a short, profound book he wrote called 'Meditations.' We give you a peek inside this ancient wisdom.