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Robert Cianflone/Getty Images

What Exactly Is Curling?

Robert Cianflone/Getty Images
Robert Cianflone/Getty Images

Olympic curling has taken to the ice, but if you're like most Americans, this writer included, the game is a bit baffling. Here's a quick, stripped-down primer on everyone's favorite icy alternative to shuffleboard. It doesn't cover anywhere near all of the game's nuances, but it should give you enough info that you can enjoy watching an end or two. (And yes, you'll learn what an "end" is.)

WHAT'S THE OBJECT OF CURLING?

Good question. First, let's get a bit of the jargon down. The playing surface in curling is called "the sheet." Sheet dimensions can vary, but they're usually around 150 feet long by about 15 feet wide. The sheet is covered with tiny droplets of water that become ice and cause the stones to "curl," or deviate from a straight path. These water droplets are known as "pebble."

At each end there's a target that looks like a big bullseye. These targets are known as "the houses." The center of the house is known as the "button." Basically, the object of the game is to get your stones closer to the button than the other team gets theirs.

WHAT'S WITH THE SWEEPING?

How Curling Works
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Remember how we talked about the pebble of ice droplets that the rock has to travel across? When the stone touches the pebble, there's friction, which can slow down the stone and makes it curl away from its straight path to the house.

Obviously, that friction is not always a good thing, but sweeping helps combat the problem. The sweeping motion raises the temperature of the ice by a degree or two, which diminishes the friction between the pebble and the stone and keeps the stone moving in a straight line.

WHAT ABOUT ALL THE YELLING?

Each curling team has four members: a lead, a second, a vice-skip (or third), and a skip. Each "end" (curling's equivalent of a baseball inning) involves both teams shooting (or "delivering") eight stones at the house, with players delivering two stones apiece.

When the lead, second, and vice are delivering their stones, the skip stands at the opposite end of the sheet (near the house) and uses his broom to give his teammates a target for their deliveries. Once the stone has been delivered and is a "running stone" (that is, one that's still sliding), the skip then yells to the sweepers to let them know when to sweep and how hard. When the skip shoots the last two stones of a team's end, the vice takes over calling the shots.

HOW DO YOU KEEP SCORE?

In each end, both teams send eight stones down the sheet. Once all 16 stones have been delivered, the team with the stone that's closest to the button (center of the house) effectively "wins" the end. Only this team will earn any points for the end. It gets a point for each of its stones that are in the house and closer to the button than the other team's closest stone. Since the team that won the end always has at least one stone that's closer to the button than their opponent, the team always scores at least one point, and could score up to eight points.

If neither team manages to keep a stone in the house during an end, it's known as a "blank end," and no points are scored. Olympic curling matches last for 10 ends unless there is a tie, in which case it goes to extra-ends, curling's equivalent of overtime.

WHAT'S THE HAMMER?

As you might have guessed from reading about the scoring system, throwing the last stone of an end is a huge advantage. If you've got the last stone, you can always try to knock the other team's best stone away from the button. If a team holds the last stone for an end, it "has the hammer," and should probably be able to score some points. If the team without the hammer manages to somehow stymie their opponent and score points, it's called a "stolen end." Whichever team fails to score points in an end gets the hammer for the next end.

SO IS THERE STRATEGY INVOLVED?

Yes, there's all sorts of strategy in curling. Let's say your team doesn't have the hammer. You're at a huge disadvantage when it comes to scoring points, so you might opt to play defensively. To do that, you might just deliver a number of "guards," or rocks that will sit in front of the house and provide an obstacle for the other team's stones. Alternatively, guards can be used to defend your stones that are already in the house from being knocked out by the other team's "takeout" shots.

The third major type of curling shot is the "draw," a shot that's meant to avoid other stones and come to rest in the house. Generally, a draw is used with the hope of scoring points, a guard is thrown to protect the house or a stone that's already been thrown, and a takeout is used defensively.

MAY I SEE A CLIP?

Yes you may.

This post was originally published in 2010.

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Big Questions
Do Bacteria Have Bacteria?
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Drew Smith:

Do bacteria have bacteria? Yes.

We know that bacteria range in size from 0.2 micrometers to nearly one millimeter. That’s more than a thousand-fold difference, easily enough to accommodate a small bacterium inside a larger one.

Nothing forbids bacteria from invading other bacteria, and in biology, that which is not forbidden is inevitable.

We have at least one example: Like many mealybugs, Planococcus citri has a bacterial endosymbiont, in this case the β-proteobacterium Tremblaya princeps. And this endosymbiont in turn has the γ-proteobacterium Moranella endobia living inside it. See for yourself:

Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)
Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)

I don’t know of examples of free-living bacteria hosting other bacteria within them, but that reflects either my ignorance or the likelihood that we haven’t looked hard enough for them. I’m sure they are out there.

Most (not all) scientists studying the origin of eukaryotic cells believe that they are descended from Archaea.

All scientists accept that the mitochondria which live inside eukaryotic cells are descendants of invasive alpha-proteobacteria. What’s not clear is whether archeal cells became eukaryotic in nature—that is, acquired internal membranes and transport systems—before or after acquiring mitochondria. The two scenarios can be sketched out like this:


The two hypotheses on the origin of eukaryotes:

(A) Archaezoan hypothesis.

(B) Symbiotic hypothesis.

The shapes within the eukaryotic cell denote the nucleus, the endomembrane system, and the cytoskeleton. The irregular gray shape denotes a putative wall-less archaeon that could have been the host of the alpha-proteobacterial endosymbiont, whereas the oblong red shape denotes a typical archaeon with a cell wall. A: archaea; B: bacteria; E: eukaryote; LUCA: last universal common ancestor of cellular life forms; LECA: last eukaryotic common ancestor; E-arch: putative archaezoan (primitive amitochondrial eukaryote); E-mit: primitive mitochondrial eukaryote; alpha:alpha-proteobacterium, ancestor of the mitochondrion.

The Archaezoan hypothesis has been given a bit of a boost by the discovery of Lokiarcheota. This complex Archaean has genes for phagocytosis, intracellular membrane formation and intracellular transport and signaling—hallmark activities of eukaryotic cells. The Lokiarcheotan genes are clearly related to eukaryotic genes, indicating a common origin.

Bacteria-within-bacteria is not only not a crazy idea, it probably accounts for the origin of Eucarya, and thus our own species.

We don’t know how common this arrangement is—we mostly study bacteria these days by sequencing their DNA. This is great for detecting uncultivatable species (which are 99 percent of them), but doesn’t tell us whether they are free-living or are some kind of symbiont. For that, someone would have to spend a lot of time prepping environmental samples for close examination by microscopic methods, a tedious project indeed. But one well worth doing, as it may shed more light on the history of life—which is often a history of conflict turned to cooperation. That’s a story which never gets old or stale.

This post originally appeared on Quora. Click here to view.

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Big Questions
Why Do Cats 'Blep'?
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As pet owners are well aware, cats are inscrutable creatures. They hiss at bare walls. They invite petting and then answer with scratching ingratitude. Their eyes are wandering globes of murky motivations.

Sometimes, you may catch your cat staring off into the abyss with his or her tongue lolling out of their mouth. This cartoonish expression, which is atypical of a cat’s normally regal air, has been identified as a “blep” by internet cat photo connoisseurs. An example:

Cunning as they are, cats probably don’t have the self-awareness to realize how charming this is. So why do cats really blep?

In a piece for Inverse, cat consultant Amy Shojai expressed the belief that a blep could be associated with the Flehmen response, which describes the act of a cat “smelling” their environment with their tongue. As a cat pants with his or her mouth open, pheromones are collected and passed along to the vomeronasal organ on the roof of their mouth. This typically happens when cats want to learn more about other cats or intriguing scents, like your dirty socks.

While the Flehmen response might precede a blep, it is not precisely a blep. That involves the cat’s mouth being closed while the tongue hangs out listlessly.

Ingrid Johnson, a certified cat behavior consultant through the International Association of Animal Behavior Consultants and the owner of Fundamentally Feline, tells Mental Floss that cat bleps may have several other plausible explanations. “It’s likely they don’t feel it or even realize they’re doing it,” she says. “One reason for that might be that they’re on medication that causes relaxation. Something for anxiety or stress or a muscle relaxer would do it.”

A photo of a cat sticking its tongue out
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If the cat isn’t sedated and unfurling their tongue because they’re high, then it’s possible that an anatomic cause is behind a blep: Johnson says she’s seen several cats display their tongues after having teeth extracted for health reasons. “Canine teeth help keep the tongue in place, so this would be a more common behavior for cats missing teeth, particularly on the bottom.”

A blep might even be breed-specific. Persians, which have been bred to have flat faces, might dangle their tongues because they lack the real estate to store it. “I see it a lot with Persians because there’s just no room to tuck it back in,” Johnson says. A cat may also simply have a Gene Simmons-sized tongue that gets caught on their incisors during a grooming session, leading to repeated bleps.

Whatever the origin, bleps are generally no cause for concern unless they’re doing it on a regular basis. That could be sign of an oral problem with their gums or teeth, prompting an evaluation by a veterinarian. Otherwise, a blep can either be admired—or retracted with a gentle prod of the tongue (provided your cat puts up with that kind of nonsense). “They might put up with touching their tongue, or they may bite or swipe at you,” Johnson says. “It depends on the temperament of the cat.” Considering the possible wrath involved, it may be best to let them blep in peace.

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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