Why Don't Woodpeckers Get Brain Damage?

pablo_arriaran/iStock via Getty Images
pablo_arriaran/iStock via Getty Images

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.

What’s the Difference Between a Pirate and a Buccaneer?

geniebird/iStock via Getty Images
geniebird/iStock via Getty Images

Talk Like a Pirate Day is returning to port on September 19th and you can bet your boots that a few celebrants will be using the terms pirate and buccaneer interchangeably. Most people do. Nevertheless, these two words aren’t actually synonymous.  

Four hundred years ago, if you were a seafaring thief, the label that you received said a great deal—mainly about whoever it was doing the labeling. Anyone who called you a "pirate" probably hated your guts. But those who cited you as a “buccaneer” might have had a very different attitude. Within certain contexts, the latter group may have even embraced you as a national hero.

Time for a swashbuckling semantics lesson. In article 101 of the United Nations Convention on the Law of the Sea (UNCLOS), piracy is defined as "any illegal acts of violence or detention ... committed for private ends by the crew or the passengers of a private ship." UNCLOS also states that, to be considered piracy, a crime must occur within international waters. If the event in question takes place within a particular country’s territorial waters, the aggressors will be deemed armed robbers rather than pirates.

Historical definitions tended to be a lot broader. During the 17th and 18th centuries, England regarded piracy as any criminal act committed on the high seas or below the low tide mark around shores, rivers, and estuaries. Hundreds of years earlier, in the year 100 CE, Plutarch—a noteworthy Greek scholar— talked about pirates as anybody who attacked a ship or maritime city without legal authority.

Just what did he mean by “legal authority?” Plutarch was probably alluding to warships. Nowadays, these are generally owned by national governments, but this wasn’t always the case. From medieval times through the early 20th century, it was common practice for a nation at war to recruit private vessels to assault its enemy’s ships, steal their goods, and plunder their ports. Mariners who engaged in such state-approved mischief were called “privateers.”

Usually, a privateer vessel was allowed to operate under a license that was granted by the country it served. Dubbed the Letter of Marque, this document laid out a code of conduct and payment policy for the crew. (Privateers almost always got to keep a percentage of whatever they took.)

Essentially, privateers were independent contractors, acting as hostile, government-commissioned, seafaring mercenaries. Therefore, they technically weren’t pirates because real pirates didn’t behave in accordance with any national laws or regulations. But the dividing line here was pretty blurry. Many privateers eventually became pirates and vice versa. Also, a captured privateer would sometimes be tried as a pirate by the country he or she was victimizing.

This brings us back to buccaneers: Throughout the 16th through 18th centuries, Spain more or less controlled the Caribbean. However, in the 1600s, she started to get some not-so-friendly competition. By the middle of that century, settlers from various other European countries—including England, France, and the Netherlands—had colonized parts of the Leeward Islands and Hispaniola. Among these newcomers, transplanted Frenchmen were especially common. The Gallic colonists would frequently smoke their meat over a wooden platform that they called a boucan. Thanks to this cooking technique, the frontiersmen were given the nickname “buccaneers.”

Before long, many turned to piracy. Because of Spain’s huge colonial presence in the Caribbean, buccaneers more or less exclusively targeted Spanish ports and ships. This turned plenty of heads across the Atlantic. In an attempt to cripple Spain’s empire, the English, French, and Dutch began issuing Letters of Marque to buccaneer vessels.

Eventually, the word buccaneer came to possess its current—and very specific—definition, which is: “any of the piratical adventurers who raided Spanish colonies and ships along the American coast in the second half of the 17th century.” (Told you it was specific.)

The most famous buccaneer of them all was undoubtedly Sir Henry Morgan. Little is known about his early life, although most historians believe that he was born in Wales at some point in 1635. Nearly 20 years later, he set sail for Barbados as a member of an expedition that saw England seize Jamaica from the Spanish.

Morgan quickly emerged as a leading buccaneer, and as England’s most ruthlessly effective privateer. In 1668, he seized the heavily guarded city of Porto Bello, Panama, holding it for ransom until the Spanish coughed up an amazing 250,000 pesos. Three years later, Morgan raided and sacked Panama City, which promptly burned to the ground. Such exploits did not endear him to the Spanish, but in England, Morgan was a widely beloved figure. Knighted by King Charles II, he was made Lieutenant Governor of Jamaica in 1674. Following his death on August 25, 1688, Morgan received a grandiose state funeral, complete with a 22-gun salute.

And, yes, that rum was named after him. Clearly, buccaneering had its perks. 

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Why is Friday the 13th Considered Unlucky?

iStock
iStock

Today, people around the globe will feel uneasy about getting out of bed, leaving their homes, or going about their normal daily routines, all because of a superstition. These unfortunate folks suffer from paraskavedekatriaphobia, a common neurosis familiar to us all: the fear of Friday the 13th. But just where did this superstitious association come from, and how did it catch on?

The truth is that no one is absolutely sure where the idea that Friday the 13th is unlucky originated. Donald Dossey, the founder of the Stress Management Center and Phobia Institute in Asheville, North Carolina, suspects the fear can be traced back to a Norse myth about 12 gods who had a dinner at Valhalla—the fabled hall where legendary Norse heroes feasted for eternity after they died—that was interrupted by a 13th guest, the evil and mischievous god Loki.

According to legend, Loki tricked Höðr (the blind god of winter and son of Odin, the supreme god in Norse mythology) into shooting his brother Baldr (the benevolent god of summer who was also a son of Odin) with a magical spear tipped with mistletoe—the only substance that could defeat him. Thus the number 13 was branded as unlucky because of the ominous period of mourning following the loss of such powerful gods by this unwanted 13th guest.

For whatever reason, among many cultures, the number 12 emerged throughout history as a "complete" number: There are 12 months in a year, 12 signs of the zodiac, 12 Gods of Olympus, 12 sons of Odin, 12 labors of Hercules, 12 Jyotirlingas or Hindu shrines where Shiva is worshipped, 12 successors of Muhammad in Shia Islam, and 12 tribes of Israel. In Christianity, Jesus was betrayed by one of his 12 Apostles—Judas—who was the 13th guest to arrive for the Last Supper. Surpassing the number 12 ostensibly unbalances the ideal nature of things; because it is seen as irregular and disrespectful of a sense of perfection, the number 13 bears the stigma of misfortune and bad luck we know today.

WHY FRIDAY?

Friday joins in the mix mostly because all of the early accounts of Jesus’s crucifixion agree that it took place on Friday—the standard day for crucifixions in Rome. As Chaucer noted in The Canterbury Tales, "And on a Friday fell all this mischance." Yet perpetuating Friday as an unlucky day in America came from the late 19th-century American tradition of holding all executions on Fridays; Friday the 13th became the unluckiest of days simply because it combined two distinct superstitions into one. According to the Oxford University Press Dictionary of Superstitions, the first reference to Friday the 13th itself wasn’t until 1913. (So despite actually occurring on Friday, October 13, 1307, the popular notion that the Friday the 13th stigma comes from the date on which the famed order of the Knights Templar were wiped out by King Philip of France is just a coincidence.)

The repercussions of these phobias reverberated through American culture, particularly in the 20th century. Most skyscrapers and hotels lack a 13th floor, which specifically comes from the tendency in the early 1900s for buildings in New York City to omit the unlucky number (though the Empire State Building has a 13th floor). Some street addresses also skip from 12 to 14, while airports may skip the 13th gate. Allegedly, the popular Friday the 13th films were so-named just to cash in on this menacing date recognition, not because the filmmakers actually believed the date to be unlucky.

So, is Friday the 13th actually unlucky? Despite centuries of superstitious behavior, it largely seems like psychological mumbo jumbo. One 1993 study seemed to reveal that, statistically speaking, Friday the 13th is unlucky, but the study's authors told LiveScience that though the data was accurate, "the paper was just a bit of fun and not to be taken seriously." Other studies have shown no correlation between things like increased accidents or injuries and Friday the 13th.

And Friday the 13th isn't a big deal in other cultures, which have their own unlucky days: Greeks and Spanish-speaking countries consider Tuesday the 13th to be the unluckiest day, while Italians steer clear of Friday the 17th. So today, try to rest a little easy—Friday the 13th may not be so unlucky after all.

Additional Source: 13: The Story of the World’s Most Popular Superstition.

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