How Can Owls Rotate Their Heads 270 Degrees Without Dying?

Thinkstock
Thinkstock

For humans, sudden gyrations of the head and neck—whether they’re from car accidents, rollercoaster rides, or chiropracty gone awry—can tear blood vessel linings in the neck, leading to clots that can cause stroke. Not so in owls, which can quickly rotate their heads 270 degrees in either direction without damaging blood vessels or cutting off blood flow to the brain. How do they do it?

To solve the mystery, scientists at Johns Hopkins—led by medical illustrator Fabian de Kok-Mercado and neuroradiologist Philippe Gailloud—used angiography and CT scans to examine the anatomy of a dozen snowy, barred, and great horned owls that died from natural causes. They discovered that the birds are equipped with four biological adaptations that prevent injury from rapid rotational movement; their study appears in the latest issue of Science.

“Until now, brain imaging specialists like me who deal with human injuries caused by trauma to arteries in the head and neck have always been puzzled as to why rapid, twisting head movements did not leave thousands of owls lying dead on the forest floor from stroke," Gailloud said in a press release announcing the results of the study. "The carotid and vertebral arteries in the neck of most animals—including owls and humans—are very fragile and highly susceptible to even minor tears of the vessel lining.”

After x-raying, dissecting and analyzing blood vessels from the dead birds’ necks, the researchers injected dye into the dead owls’ arteries to mimic blood flow and manually turned their heads. What they found was surprising: Unlike in humans, whose arteries shrink as the head turns, the blood vessels just under the jaw at the base of the owls’ heads got increasingly larger as more of the dye entered, but before the fluid pooled into reservoirs. These contractile reservoirs, scientists say, are what allow owls to turn their heads so radically while still having enough blood to feed the eyes and the brain. What's more, a complex supporting vasular network minimizes interruptions in blood flow; the scientists discovered that owls have small vessel connections between the carotid and vertebral arteries that allow blood to flow between the two vessels—so even if one route is blocked by an extreme neck rotation, another can provide an uninterrupted blood flow to the brain.



Click to enlarge.

Bones in owls’ necks also have adaptations designed to facilitate extreme rotation. One of the major arteries feeding the birds' brains passes through holes in the vertebrae, called transverse foramine; the team found that these holes were 10 times larger in diameter than the artery. This extra space creates air pockets that allow the artery to move around when twisted; 12 of the vertebrae in the owls’ necks had this adaptation. "In humans, the vertebral artery really hugs the hollow cavities in the neck. But this is not the case in owls, whose structures are specially adapted to allow for greater arterial flexibility and movement," said de Kok-Mercado. Plus, the owls’ vertebral artery enters the neck higher than it does in other birds’—going in at the 12th cervical vertebrae, rather than the 14th—allowing for more slack.

"Our new study results show precisely what morphological adaptations are needed to handle such head gyrations and why humans are so vulnerable to osteopathic injury from chiropractic therapy," Gailloud said. "Extreme manipulations of the human head are really dangerous because we lack so many of the vessel-protecting features seen in owls." The team created a poster (above) that details their findings, and next plans to study hawk anatomy to see if those birds have similar adaptations for head rotation.

Who Has Jurisdiction for Crimes Committed in Space?

iStock/nedelcupaul
iStock/nedelcupaul

It's 2050. Humans have mastered commercial space travel. Hundreds of people pay thousands of dollars to be sent into orbit in a spaceship. Maybe some decide to help colonize Mars.

Then, trouble. A jilted spouse. A smuggled firearm. Perhaps a struggle followed by suffocation. A space traveler is found dead on board a ship or on the Red Planet. Who has jurisdiction over such crimes? Is there such a thing as a cosmic Hercule Poirot? Could someone fall through the cracks and get away with space murder?

To date, no one has been victim of a space crime. But because no one nation can lay claim to ownership of space, the idea of a criminal offense committed outside of our atmosphere is something people have already given some thought to.

According to NASA engineer and instructor Robert Frost, the language of law for galactic felonies would be the Outer Space Treaty of 1967. In Article VIII of the treaty, nations engaging in space exploration agree that they will bear responsibility for the actions of personnel aboard their craft. In other words, if a privatized shuttle from China sees a fight break out among crew members, leaving one injured, China would be the entity responsible for handling legal repercussions.

That varies slightly with the International Space Station, or ISS, which is home to a number of personnel from different nations. In the case of the ISS, an intergovernmental agreement signed in 1998 mandates that the home country of the offender will handle any investigation or prosecution. If the victim is a national of another country, that country will have the right to inquire as to the criminal status of the offender and seek to have jurisdiction over the matter if they feel justice isn't being meted out.

In most cases, space crime sprees would be treated the same as if an offender was traveling in a foreign country or in international waters. If you're a U.S. citizen and decide to bludgeon someone at sea or on the Moon, the various international agreements and national laws would determine how you get prosecuted. (Assuming, of course, you returned to Earth to answer the charges.)

Space crimes pose another intriguing wrinkle. In terra firma investigations, authorities can secure crime scenes, question witnesses, and preserve evidence. Aboard a spaceship or on a distant planet, these procedures would be difficult to perform, and almost impossible to do in a timely fashion. Even if a criminal investigator is on Mars, low gravity will affect blood spatter and bodies may even decay at a different rate than they do on Earth. While an American may be found liable for murder, proving it was malicious and not the result of the dangerous environment would give any prosecutor a headache. A defense attorney, on the other hand, would have a field day questioning defective spacesuits or toxic exposure to strange space chemicals.

Then again, prosecutors may not have to concern themselves with evidence. Thanks to airlocks and restrictive suits, the movement of space travelers is highly monitored. It would be hard to make any plausible deniability about one's whereabouts.

The closest thing to space crime that law enforcement has yet encountered may be crimes committed in Antarctica, the frigid and isolated continent that's unaffiliated with any country but operates under the Antarctic Treaty signed by 54 nations. The agreement declares that the suspect is likely under their home country's jurisdiction. In some cases, the country owning the research station where the alleged crime took place steps in. In 2018, a Russian researcher at Bellingshausen Station on King George Island went after his victim with a knife in the station's dining room. He was charged in Russia, though reports indicate the case has since been dropped. And in 2000, an Australian astrophysicist suspected of being fatally poisoned had an autopsy performed in New Zealand. The exam showed he had ingested methanol, but it remains unknown whether he did so accidentally or whether someone gave it to him. New Zealand police were unable to determine the source.

A person committing murder in space would certainly be held responsible. But whether they'd ever be found guilty beyond a reasonable doubt remains very much up in—and beyond—the air.

Why Do Dogs Eat Grass?

iStock/K_Thalhofer
iStock/K_Thalhofer

If something is edible (or even if it's not), many dogs will gladly make a meal of it. But if you see your pet grazing on your front lawn like cattle, it may be driven by something more than its undiscerning appetite. Eating grass frantically can be a sign that a dog is sick.

It's not unusual to see a dog vomit after consuming grass, prompting some pet owners to wonder if their dog ate the grass to soothe its own upset stomach or if the grass is what caused its symptoms in the first place. According Dr. Jerry Klein, chief veterinary officer for the American Kennel Club, this behavior is sometimes a response to symptoms that were already present. "When dogs go outside and gobble grass really quickly, there's usually a reason, an instinctual behavior to try to induce some kind of gastrointestinal reaction," he tells Mental Floss. "When they realize they're nauseous or something else, the only thing they know how to do is to force themselves to vomit. Some dogs that eat grass chomp it down without really chewing it, and often times may vomit something up and that's how they treat themselves."

Despite it being a common issue for pet owners, little research has been done into why dogs eat grass. It's likely that stomach problems only explain this behavior part of the time. In other situations, a dog may eat grass for the same reason it eats your shoes or the groceries you left on the kitchen counter: Because it's hungry, anxious, or bored.

So how can you tell when your dog is munching grass for pleasure and when it's trying to induce itself to vomit? Pay attention to the way it eats. Dogs are omnivorous, meaning they eat both plants and animals, so just eating grass alone normally won't be enough to make it sick. But if a dog is gorging on grass faster than it can chew it, that may be an indication that something is wrong. Whole blades of grass can irritate a dog's throat and stomach lining, potentially causing them to throw up if they swallow a lot of them in a short amount of time.

No matter the reason for your dog's grass-eating habits, Klein says that they aren't a major issue. The behavior shouldn't be encouraged, as grass in public places can potentially carry harmful chemicals like pesticides, so stop your dog if you see it grazing. But if it shows no signs of illness or discomfort afterward, there's no need to rush it to the vet. "If I see a dog eating grass, I'm not going to panic. I would try to stop it and then monitor it to see how it acts in the next 15 to 20 minutes. Look at how the dog's acting, its body shape and movement, and the feeling you get from the dog."

One condition related to vomiting that would warrant a trip to the vet is something called bloat. This happens when a dog's stomach fills with air, causing it to retch without actually throwing anything up. This is a medical emergency and can be deadly if left untreated.

A dog who vomits after eating grass and looks happy afterward, on the other hand, is probably not a cause for concern—though you may argue otherwise when you're steam-cleaning your carpet.

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

SECTIONS

arrow
LIVE SMARTER