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Why Don't Woodpeckers Get Brain Damage?

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Hit your head really hard on something, and it’ll smart for a while. In worse cases, you might get a concussion, fracture your skull, or receive a brain injury that leaves you impaired or kills you (traumatic brain injuries account for nearly one third of injury-related deaths in the US).

Good thing you’re not a woodpecker, then. The lives and livelihoods of these birds revolve around slamming their heads into things. Whether it wants to get at an insect hiding in bark, excavate a space to build a nest, claim a bit of territory, or attract a mate, the woodpecker has one simple solution: bang its head against a tree trunk at speeds reaching 13 to 15 miles per hour. In an average day, a woodpecker does this around 12,000 times, and yet they don’t seem to hurt themselves or be the least bit bothered by it. This is because, after millions of years of this type of behavior, they’ve evolved some specialized headgear to prevent injuries to their heads, brains, and eyes.

To figure out what goes into woodpecker head trauma prevention, a team of Chinese scientists took a look at the birds’ skulls and brains and their pecking behavior. They watched as woodpeckers pecked at force sensors while recording them with high-speed cameras so they could see the strikes in slow motion and know how hard each blow was. They also scanned the birds’ heads with x-rays and an electron microscope to get a better look at their bone structure. Finally, they squished a few preserved woodpecker skulls in a material testing machine and, using their scans, built 3D computer models of the birds’ heads to smash in a simulation.

When all was said and done and both the virtual and actual woodpeckers' heads had taken a sound beating, the researchers found that there are a few anatomical features and other factors that come together to keep a woodpecker safe and healthy while it rat-a-tat-tats the day away.

First, a woodpecker’s skull is built to absorb shock and minimize damage. The bone that surrounds the brain is thick and spongy, and loaded with trabeculae, microscopic beam-like bits of bone that form a tightly woven “mesh” for support and protection. On their scans, the scientists found that this spongy bone is unevenly distributed in woodpeckers, and it is concentrated around the forehead and the back of the skull, where it could act as a shock absorber.

Woodpeckers' hyoid bones act as additional support structures. In humans, the horseshoe-shaped hyoid is an attachment site for certain throat and tongue muscles. Woodpeckers’ hyoids do the same job, but they’re much larger and are differently shaped. The ends of the “horseshoe” wrap all the way around the skull and, in some species, even around the eye socket or into the nasal cavity, eventually meeting to form a sort of sling shape. This bizarre-looking bone, the researchers think, acts like a safety harness for the woodpecker’s skull, absorbing shock stress and keeping it from shaking, rattling and rolling with each peck.

Inside the skull, the brain has its own defenses. It’s small and smooth, and is positioned in a tight space with its largest surface pointing towards the front of the skull. It doesn’t move around too much, and when it does collide with the skull, the force is spread out over a larger area. This makes it more resistant to concussions, the researchers say.

A woodpecker’s beak helps prevent trauma, too. The outer tissue layer of its upper beak is longer than the lower beak, creating a kind of overbite, and the bone structure of the lower beak is longer and stronger than the upper one. The researchers think that the uneven build diverts impact stress away from the brain and distributes it to the lower beak and bottom parts of the skull instead.

The woodpecker’s anatomy doesn’t just prevent injuries to the brain, but also its eyes. Other research using high-speed recordings has shown that, in the fraction of a second just before their beaks strike wood, woodpeckers’ thick nictitans—membranes beneath the lower lid of their eyes, sometimes called the “third eyelid”—close over the eyes. This protects them from debris and keeps them in place. They act like seatbelts, says ophthalmologist Ivan Schwab, author of Evolution's Witness: How Eyes Evolved, and they keep the retina from tearing and the eye from popping right out of the skull.

There’s also a behavioral aspect to the damage control. The researchers found that woodpeckers are pretty good at varying the paths of their pecks. By moving their heads and beaks around as they hammer away, they minimize the number of times in a row that the brain and skull make contact at the same point. Older research also showed that the strike trajectories, as much as they vary, are always almost linear. There’s very little, if any, rotation of the head and almost no movement immediately after impact, minimizing twisting force that could cause injury.

Earlier this year, another group of researchers in China found that, with all of these adaptations, 99.7 percent of the impact energy from striking a tree is absorbed by the body, but a little bit—that last 0.3 percent—does go to the head and the brain. That mechanical energy gets converted into heat, which causes the temperature of a woodpecker’s brain to increase, but the birds seem to have a way dealing with that, too. Woodpeckers usually peck in short bursts with breaks in between, and the researchers think that these pauses give the brain time to cool down before the head banging starts again and brings the temperature back up.

This story was originally published in 2012. It was updated with new information in 2014.

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Big Questions
Why Does Santa Claus Give Coal to Bad Kids?
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The tradition of giving misbehaving children lumps of fossil fuel predates the Santa we know, and is also associated with St. Nicholas, Sinterklaas, and Italy’s La Befana. Though there doesn't seem to be one specific legend or history about any of these figures that gives a concrete reason for doling out coal specifically, the common thread between all of them seems to be convenience.

Santa and La Befana both get into people’s homes via the fireplace chimney and leave gifts in stockings hung from the mantel. Sinterklaas’s controversial assistant, Black Pete, also comes down the chimney and places gifts in shoes left out near the fireplace. St. Nick used to come in the window, and then switched to the chimney when they became common in Europe. Like Sinterklaas, his presents are traditionally slipped into shoes sitting by the fire.

So, let’s step into the speculation zone: All of these characters are tied to the fireplace. When filling the stockings or the shoes, the holiday gift givers sometimes run into a kid who doesn’t deserve a present. So to send a message and encourage better behavior next year, they leave something less desirable than the usual toys, money, or candy—and the fireplace would seem to make an easy and obvious source of non-presents. All the individual would need to do is reach down into the fireplace and grab a lump of coal. (While many people think of fireplaces burning wood logs, coal-fired ones were very common during the 19th and early 20th centuries, which is when the American Santa mythos was being established.)

That said, with the exception of Santa, none of these characters limits himself to coal when it comes to bad kids. They’ve also been said to leave bundles of twigs, bags of salt, garlic, and onions, which suggests that they’re less reluctant than Santa to haul their bad kid gifts around all night in addition to the good presents.

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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Big Questions
Who Was Heisman and Why Does He Have a Trophy?
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On Saturday night, one of three finalists will be named this year's Heisman Trophy winner. But before anyone brings home the hardware, let’s answer a few questions about John Heisman and his famous award.

Who Exactly Was John Heisman?

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His name is mostly associated with the trophy now, but Heisman (right) was a player, coach, and hugely successful innovator in the early days of football. After playing for Brown and then Penn as a collegian from 1887 to 1891, Heisman became a coach at a series of schools that included Oberlin, Buchtel, Auburn, Clemson, Penn, Washington & Jefferson, Rice, and, most notably, Georgia Tech.

For What Football Innovations Does Heisman Get Credit?

Just some little trivial stuff like snapping the ball. Centers originally placed the ball on the ground and rolled it back to their quarterbacks, who would scoop it up and make plays. When Heisman was coaching at Buchtel (which later became the University of Akron), though, he had a 6’4” QB named Harry Clark. Clark was so tall that picking the ball up off the ground was wildly inefficient, so Heisman invented the center snap as an easy way to get the ball in Clark’s hands. Heisman also innovated the use of pulling guards for running plays and the infamous hidden-ball trick.

Any Other Shenanigans on Heisman’s Resume?

You bet. When Heisman found a way to gain an edge, he jumped on it no matter how ridiculous it seemed. When Heisman was coaching at Clemson in 1902, his team traveled to Atlanta for a game against Georgia Tech. Although Heisman was known for being a rather gruff disciplinarian, the Clemson team immediately started partying upon their arrival.

When Georgia Tech’s players and fans heard that the entire Clemson squad had spent the night before the game carousing, they prepared to coast to an easy win. When the game started, though, Clemson roared out of the gate en route to a 44-5 stomping.

How did Clemson crush Tech when by all rights they should have been ridiculously hungover? The “team” that everyone had seen partying the night before wasn’t really Heisman’s Clemson squad at all. He had sent his junior varsity players to Atlanta the night before to serve as drunken decoys, then quietly slipped his varsity team in on a morning train right before the game.

What Kind of Coach Was He?

Heisman worked as an actor in community stock theater during the summer – he consistently received rotten reviews – and allegedly spoke in a brusque, yet bizarrely ostentatious manner. Georgia Tech’s website relates a story of one of Heisman’s speeches he would break out on the first day of practice while describing a football: "What is this? It is a prolate spheroid, an elongated sphere - in which the outer leather casing is drawn tightly over a somewhat smaller rubber tubing. Better to have died as a small boy than to fumble this football."

How Did His Name Get on the Trophy?

After leaving his head-coaching job at Rice in 1927, Heisman became the athletic director at New York’s Downtown Athletic Club. In 1935 the club began awarding the Downtown Athletic Club Trophy to the nation’s top college football star. (Chicago’s Jay Berwanger won the first trophy.) Heisman died of pneumonia the following fall before the second trophy could be awarded, and the club voted to rename the prize the Heisman Memorial Trophy Award.

Did He Ever Really Throw that Iconic Stiff Arm?

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Possibly, but Heisman didn’t have the ball in his hands all that much. Even though he was a fairly small guy at just 5’8” and 158 pounds, he played as a lineman throughout his college career.

The famous “Heisman pose” is actually based on Ed Smith, a former NYU running back who modeled for the trophy’s sculptor in 1934. Interestingly, Smith went years without knowing that he’d modeled for the famous trophy. His sculptor buddy Frank Eliscu had just needed a football player to model for a project, and Smith volunteered.

Smith figured Eliscu was just doing some little personal sculpture and remained totally oblivious to his spot in football history for the next 48 years until a documentary filmmaker called Smith to interview him about the Heisman in 1982. Smith initially had no idea what the guy was talking about, but he eventually remembered his modeling days. In 1985, the Downtown Athletic Club gave Smith his own copy of the Heisman, and in 1986 he even received recognition on the televised ceremony. He looked at the four finalists – Vinny Testaverde won that year – and quipped, "Whoever wins the award, I feel sorry for you, because you're going to be looking at my ugly face for a long time." [Pictured Above: Auburn's Bo Jackson in 1985.]

What’s a Heisman Trophy Worth on the Open Market?

Quite a bit. A number of Heisman winners have eventually sold their hardware, and the trophies fetch quite a bit of loot. O.J. Simpson got $230,000 for his, and several others have gone for six-figure prices. The most expensive trophy that’s changed hands was Minnesota back Bruce Smith’s 1941 award; it fetched $395,240.

How Did Steve Spurrier Change the Process?

SEC fans are going to be floored by this one, but the Ol’ Ball Coach did something really classy when he won the Heisman in 1966. Instead of taking the trophy for himself, Spurrier gave it to the University of Florida so the school could display it and let the student body enjoy it. Florida’s student government thought Spurrier’s generosity was so classy that they paid for a replica for Spurrier so he’d get to have his own trophy, too. Since then both the school and the player have received copies of the trophy.

So Heisman Must Have Been the World’s Greatest Sportsman, Right?

Well, not really. Heisman was on the victorious side of possibly the most gratuitously run-up score in sports history. In 1916 tiny Cumberland College canceled its football program and disbanded its squad, but it had previously signed a contract to travel to Atlanta to play Heisman’s Georgia Tech team. If Cumberland didn’t show up, they had to pay Georgia Tech a $3,000 penalty, which was quite a bit of cash in 1916.

Rather than forfeiting the money, Cumberland scraped together a team of 16 scrubs and went to take their walloping from Heisman’s boys. For reasons that still aren’t totally clear – some say it was to avenge an earlier baseball loss to Cumberland, while others claim Heisman wanted to make a statement about the absurdity of the old system of using total points scored to determine the national champion – the legendary coach showed Cumberland’s ragtag band no mercy. Tech went up 63-0 in the first quarter, but Heisman kept attacking until the final score was 222-0. There are tons of hilarious stats from the game, but the funniest is Georgia Tech rushing for 1,620 yards while Cumberland only squeaked out negative-96 yards on 27 carries.

This article originally appeared in 2010.

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