What’s the Difference Between Forests, Woods, and Jungles?

Jui-Chi Chan/iStock via Getty Images
Jui-Chi Chan/iStock via Getty Images

If you're an English speaker, there’s a good chance you often use the words woods, forest, and jungle correctly without even thinking about it. Even if a patch of trees takes up a significant portion of your backyard, you probably wouldn’t consider it a forest; and you wouldn’t talk about the beautiful fall foliage in New England’s jungles. Based on those examples, it seems like woods are smaller than forests, and jungles aren’t found in colder climates. This isn’t wrong—but there's more to it than that.

According to Merriam-Webster, a forest is “a dense growth of trees and underbrush covering a large tract,” while woods are “a dense growth of trees usually greater in extent than a grove and smaller than a forest.” The reason we consider forests to be larger than woods dates back to the Norman rule of Great Britain in 1066, when a forest was a plot of land owned by the Crown that was large enough to accommodate game for royal hunting parties. Whether that land contained trees or not was essentially irrelevant.

These days, scientists and land managers definitely consider the presence of trees necessary for land to be classified as a forest. To set it apart from woods, or woodland, it usually has to meet certain density qualifications, which are different depending on whom you ask.

According to the UN Food and Agricultural Organization (FAO), a forest must cover about 1.24 acres of land, and its canopy cover—the amount of land covered by the treetops—must exceed 10 percent of the acreage [PDF]. “Other wooded land” must also span about 1.24 acres, but its canopy cover is between 5 and 10 percent. In a nutshell, the FAO thinks forests and woods are the same size, but forests are more dense than woods. Australia, on the other hand, employs plant ecologist Raymond Specht’s classification system for its vegetation, in which any tree-populated land with less than 30 percent canopy cover is a woodland, and anything more dense than that is a forest.

Unlike forests, jungles don’t have specific scientific classifications, because the word jungle isn’t really used by scientists. According to Sciencing, it’s a colloquial term that usually denotes what scientists refer to as tropical forests.

Tropical forests are located around the Equator and have the highest species diversity per area in the world. Since they’re so densely populated with flora and fauna, it makes sense that both Merriam-Webster and the Encyclopedia Britannica describe jungles as “tangled” and “impenetrable.” They’re bursting with millions of plants and animals that are different from what we see in temperate and boreal forests to the north.

Because most of us aren’t in the habit of clarifying which type of forest we’re talking about in casual conversation, it’s no surprise that we often refer to the temperate forests we see in our own climate simply as forests, which we differentiate from those rich, overgrown tropical territories to the south by calling them jungles.

To summarize, forests are historically and colloquially considered to be larger than woods, and scientifically considered to be more dense. Jungles are technically forests, too, since jungle is a casual word for what scientists call a tropical forest.

And, all differences aside, it’s relaxing to spend time in any of them—here are 11 scientific reasons why that’s true.

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What is Mercury in Retrograde, and Why Do We Blame Things On It?

NASA
NASA

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding. For 2020, that means February 17 through March 10; June 18 through July 12; and October 14 through November 3. But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?

The History of "Mercury in Retrograde"

Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.

What is Mercury in Retrograde?

Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."

This piece originally ran in 2018.

Why Are CVS Receipts So Incredibly Long?

cyano66/iStock via Getty Images
cyano66/iStock via Getty Images

If you’ve ever conducted business at one of the nearly 10,000 CVS Pharmacy locations in the United States and count yourself among one of the estimated 62 million members of the store's ExtraCare discount incentive program, you’ve probably been handed a receipt that is more scroll than slip. These transactional documents, which have been known to literally be several feet of thermal paper long and full of merchandise coupons, are often wadded or folded up like a bath towel and handed off to the consumer.

Is this an environmentally mindful practice? And do these coupons really keep people coming back for more?

CVS has stated that the lengthy receipts are intended to demonstrate the value of being an ExtraCare member by offering ExtraCare Rewards, typically a dollar or percentage amount off of a single item or purchase. Some of the receipt's oversized real estate is also taken up by a solicitation to participate in a satisfaction survey. (Though it’s not likely that one of the questions is about the length of the receipt.)

A woman is pictured holding up a CVS receipt
stephen boisvert, Flickr // CC BY 2.0

Simply put, the chain wants to vividly illustrate the benefits of being an ExtraCare member, which also helps the company by allowing them to track your purchase history. The idea is that the Russian novel-length receipt will excite consumers who feel as though a surplus of savings are being delivered right into their hands.

The problem is that the coupons are often quick to expire or can sometimes exclude sale items, registering disappointment when a returning customer presents a slip for $2 off a bar of soap.

You can, of course, opt out of receiving a paper receipt through your ExtraCare account online or via the app, though the process requires a few steps to complete. The coupons will then be sent digitally via your smartphone. Since introducing that paperless option in 2016, the company claims it has saved 3 billion inches of paper that would otherwise have been squeezed into a ball and stuffed into your glove compartment.

Alternately, you can always use it to replace a broken window blind.

Which brings us to the other and possibly most important motivation for those long receipts: Social media engagement. The more people express dismay at those long receipts, the more exposure CVS receives. Considering their 2018 merger with health insurance giant Aetna cost more than $70 billion, some free publicity could come in handy.

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