Head Case: What the Only Soft Tissue Dodo Head in Existence Is Teaching Scientists About These Extinct Birds

Dodo: © Oxford University, Oxford University Museum of Natural History. Background: iStock
Dodo: © Oxford University, Oxford University Museum of Natural History. Background: iStock

Of all the recently extinct animals, none seems to excite the imagination quite like the dodo—a fact Mark Carnall has experienced firsthand. As one of two Life Collections Managers at the UK's Oxford University Museum of Natural History, he’s responsible for nearly 150,000 specimens, “basically all the dead animals excluding insects and fossils,” he tells Mental Floss via email. And that includes the only known soft tissue dodo head in existence.

“In the two and a bit years that I’ve been here, there’s been a steady flow of queries about the dodo from researchers, artists, the public, and the media,” he says. “This is the third interview about the dodo this week! It’s definitely one of the most popular specimens I look after.”

The dodo, or Raphus cucullatus, lived only on the island of Mauritius (and surrounding islets) in the Indian Ocean. First described by Vice Admiral Wybrand van Warwijck in 1598, it was extinct less than 100 years later (sailors' tales of the bird, coupled with its rapid extinction, made many doubt that the dodo was a real creature). Historians still debate the extent that humans ate them, but the flightless birds were easy prey for the predators, including rats and pigs, that sailors introduced to the isolated island of Mauritius. Because the dodo went extinct in the 1600s (the actual date is still widely debated), museum specimens are very, very rare. In fact, with the exception of subfossils—the dark skeletons on display at many museums—there are only three other known specimens, according to Carnall, “and one of those is missing.” (The fully feathered dodos you might have seen in museums? They're models, not actual zoological specimens.)

A man standing with a Dodo skeleton and a reconstructed model of the extinct bird
A subfossil (bone that has not been fully fossilized) Dodo skeleton and a reconstructed model of the extinct bird in a museum in Wales circa 1938.
Becker, Fox Photos/Getty Images

Since its extinction was confirmed in the 1800s, Raphus cucullatus has been an object of fascination: It’s been painted and drawn, written about and scientifically studied, and unfairly become synonymous with stupidity. Even now, more than 300 years since the last dodo walked the Earth, there’s still so much we don’t know about the bird—and Oxford’s specimen might be our greatest opportunity to unlock the mysteries surrounding how it behaved, how it lived, how it evolved, and how it died.

 
 

To put into context how old the dodo head is, consider this: From the rule of Oliver Cromwell to the reign of Queen Elizabeth II, it has been around—and it’s likely even older than that. Initially an entire bird (how exactly it was preserved is unclear), the specimen belonged to Elias Ashmole, who used his collections to found Oxford’s Ashmolean Museum in 1677. Before that, it belonged to John Tradescant the Elder and his son; a description of the collection from 1656 notes the specimen as “Dodar, from the Island Mauritius; it is not able to flie being so big.”

And that’s where the dodo’s provenance ends—beyond that, no one knows where the specimen came from. “Where the Tradescants got the dodo from has been the subject of some speculation,” Carnall says. Some live dodos did make it to Europe from Mauritius, and the museum thought its specimen might have been one of those birds—but new research, published after Mental Floss's initial interview with Carnall, casts doubt on that theory: After scanning the head, Carnall's colleagues at the museum and Warwick University discovered that the bird had been shot in the back of the head with pellets used to hunt birds in the 1600s. Though the pellets didn't penetrate the dodo's thick skull, "the researchers suggest it was a fatal shooting," Carnall tells Mental Floss in an email. "This new evidence perhaps indicates it wasn’t the remains of a live dodo brought back from Mauritius—unless it was a rather heavy-handed way of putting a dodo down."

The discovery raises questions not just about where the dodo was shot and who killed it but, as Oxford University Museum of Natural History director Paul Smith told The Guardian, about how made it to London with its skin and feathers intact. "If it was [shot] in Mauritius," he said, "there is a really serious question about how it was preserved and transported back, because they didn’t have many of the techniques that we use in the modern day to preserve soft tissues.” As Carnall says, "The mystery continues."

Initially, the specimen was just another one of many in the museum’s collections, and in 1755, most of the body was disposed of because of rot. But in the 19th century, when the extinction of the dodo was confirmed, there was suddenly renewed interest in what remained. Carnall writes on the museum’s blog that John Duncan, then the Keeper of the Ashmolean Museum, had a number of casts of the head made, which were sent to scientists and institutions like the British Museum and Royal College of Surgeons. Today, those casts—and casts of those casts—can be found around the world. (Carnall is actively trying to track them all down.)

The Oxford University Dodo head with scoleric bone and the skin on one side removed.
The Oxford University Dodo head with skin and sclerotic ring.
© Oxford University, Oxford University Museum of Natural History // Used with permission

In the 1840s, Sir Henry Acland, a doctor and teacher, dissected one side of the head to expose its skeleton, leaving the skin attached on the other side, for a book about the bird by Alexander Gordon Melville and H.E. Strickland called The dodo and its kindred; or, The history, affinities, and osteology of the dodo, solitaire, and other extinct birds of the islands Mauritius, Rodriguez and Bourbon. Published in 1848, “[It] brought together all the known accounts and depictions of the dodo,” Carnall says. The Dodo and its kindred further raised the dodo’s profile, and may have been what spurred schoolteacher George Clark to take a team to Mauritius, where they found the subfossil dodo remains that can be seen in many museums today.

Melville and Strickland described Oxford’s specimen—which they believed to be female—as being “in tolerable preservation ... The eyes still remain dried within the sockets, but the corneous extremity of the beak has perished, so that it scarcely exhibits that strongly hooked termination so conspicuous in all the original portraits. The deep transverse grooves are also visible, though less developed than in the paintings.”

Today, the specimen includes the head as well as the sclerotic ring (a bony feature found in the eyes of birds and lizards), a feather (which is mounted on a microscope slide), tissue samples, the foot skeleton, and scales from the foot. “Considering it’s been on display in collections and museums, pest eaten, dissected, sampled and handled by scientists for over 350 years,” Carnall says, “it’s in surprisingly good condition.”

 
 

There’s still much we don’t know about the dodo, and therefore a lot to learn. As the only soft tissue of a dodo known to exist, the head has been studied for centuries, and not always in ways that we would approve of today. “There was quite some consideration about dissecting the skin off of the head by Sir Henry Acland,” Carnall says. “Sadly there have also been some questionable permissions given, such as when [Melville] soaked the head in water to manipulate the skin and feel the bony structure. Excessive handling over the years has no doubt added to the wear of the specimen.”

Today, scientists who want to examine the head have to follow a standard protocol. “The first step is to get in touch with the museum with details about access requirements ... We deal with enquiries about our collections every single day,” Carnall says. “Depending on the study required, we try to mitigate damage and risk to specimens. For destructive sampling—where a tissue sample or bone sample is needed to be removed from the specimen and then destroyed for analysis—we weigh up the potential importance of the research and how it will be shared with the wider community.”

In other words: Do the potential scientific gains outweigh the risk to the specimen? “This,” Carnall says, “can be a tough decision to make.”

The head, which has been examined by evolutionary biologist Beth Shapiro and extinction expert Samuel Turvey as well as dodo experts Julian Hume and Jolyon Parish, has been key in many recent discoveries about the bird. “[It] has been used to understand what the dodo would have looked like, what it may have eaten, where it fits in with the bird evolutionary tree, island biogeography and of course, extinction,” Carnall says. In 2011, scientists took measurements from dodo remains—including the Oxford specimen—and revised the size of the bird from the iconic 50 pounder seen in paintings to an animal “similar to that of a large wild turkey.” DNA taken from specimen’s leg bone has shed light on how the dodo came to Mauritius and how it was related to other dodo-like birds on neighboring islands [PDF]. That DNA also revealed that the dodo’s closest living relative is the Nicobar pigeon [PDF].

A nicobar pigeon perched on a bowl of food.
A nicobar pigeon.
iStock

Even with those questions answered, there are a million more that scientists would like to answer about the dodo. “Were there other species—plants, parasites—that depended on the dodo?” Carnall asks. “What was the soft tissue like? ... How and when did the dodo and the related and also extinct Rodrigues solitaire colonize the Mascarene Islands? What were their brains like?”

 
 

Though it’s a rare specimen, and priceless by scientific standards, the dodo head is, in many ways, just like all the rest of the specimens in the museum’s collections. It’s stored in a standard archival quality box with acid-free tissue paper that’s changed regularly. (The box is getting upgraded to something that Carnall says is “slightly schmancier” because “it gets quite a bit of use, more so than the rest of the collection.”) “As for the specific storage, we store it in vault 249 and obviously turn the lasers off during the day,” Carnall jokes. “The passcode for the vault safe is 1234ABCD …”

According to Carnall, even though there are many scientific and cultural reasons why the dodo head is considered important, to him, it isn’t necessarily more important than any of the other 149,999 specimens he’s responsible for.

“Full disclosure: All museum specimens are equally important to collections managers,” he says. “It is a huge honor and a privilege to be responsible for this one particular specimen, but each and every specimen in the collection also has the power to contribute towards our knowledge of the natural world ... This week I was teaching about a species of Greek woodlouse and the molluscs of Oxfordshire. We know next to nothing about these animals—where they live, what they eat, the threats to them, and the predators that rely on them. The same is true of most living species, sadly. But on the upside, there’s so much work to be done!”

The Science Behind Brining Your Thanksgiving Turkey

iStock.com/LazingBee
iStock.com/LazingBee

At many Thanksgiving tables, the annual roast turkey is just a vehicle for buttery mash and creamy gravy. But for those who prefer their bird be a main course that can stand on its own without accoutrements, brining is an essential prep step—despite the fact that it requires finding enough room in the fridges to immerse a 20-pound animal in gallons of salt water for days on end. To legions of brining believers, the resulting moist bird is worth the trouble.

How, exactly, does a salty soak yield juicy meat? And what about all the claims from a contingency of dry brine enthusiasts: Will merely rubbing your bird with salt give better results than a wet plunge? For a look at the science behind each process, we tracked down a couple of experts.

First, it's helpful to know why a cooked turkey might turn out dry to begin with. As David Yanisko, a culinary arts professor at the State University of New York at Cobleskill, tells Mental Floss, "Meat is basically made of bundles of muscle fibers wrapped in more muscle fibers. As they cook, they squeeze together and force moisture out," as if you were wringing a wet sock. Hence the incredibly simple equation: less moisture means more dryness. And since the converse is also true, this is where brining comes in.

Your basic brine consists of salt dissolved in water. How much salt doesn't much matter for the moistening process; its quantity only makes your meat and drippings more or less salty. When you immerse your turkey in brine—Ryan Cox, an animal science professor at the University of Minnesota, quaintly calls it a "pickling cover"—you start a process called diffusion. In diffusion, salt moves from the place of its highest concentration to the place where it's less concentrated: from the brine into the turkey.

Salt is an ionic compound—its sodium molecules have a positive charge and its chloride molecules have a negative charge, but they stick together anyway. As the brine penetrates the bird, those salt molecules meet both positively and negatively charged protein molecules in the meat, causing the meat proteins to scatter. Their rearrangement "makes more space between the muscle fibers," Cox tells Mental Floss. "That gives us a broader, more open sponge for water to move into."

The salt also dissolves some of the proteins, which, according to the book Cook's Science by the editors of Cook's Illustrated, creates "a gel that can hold onto even more water." Juiciness, here we come!

There's a catch, though. Brined turkey may be moist, but it can also taste bland—infusing it with salt water is still introducing, well, water, which is a serious flavor diluter. This is where we cue the dry briners. They claim that using salt without water both adds moisture and enhances flavor: win-win.

Turkey being prepared to cook.
iStock

In dry brining, you rub the surface of the turkey with salt and let it sit in a cold place for a few days. Some salt penetrates the meat as it sits—with both dry and wet brining, Cox says this happens at a rate of about 1 inch per week. But in this process, the salt is effective mostly because of osmosis, and that magic occurs in the oven.

"As the turkey cooks, the [contracting] proteins force the liquid out—what would normally be your pan drippings," Yanisko says. The liquid mixes with the salt, both get absorbed or reabsorbed into the turkey and, just as with wet brining, the salt disperses the proteins to make more room for the liquid. Only this time the liquid is meat juices instead of water. Moistness and flavor ensue.

Still, Yanisko admits that he personally sticks with wet brining—"It’s tradition!" His recommended ratio of 1-1/2 cups of kosher salt (which has no added iodine to gunk up the taste) to 1 gallon of water gives off pan drippings too salty for gravy, though, so he makes that separately. Cox also prefers wet brining, but he supplements it with the advanced, expert's addition of injecting some of the solution right into the turkey for what he calls "good dispersal." He likes to use 1-1/2 percent of salt per weight of the bird (the ratio of salt to water doesn't matter), which he says won't overpower the delicate turkey flavor.

Both pros also say tossing some sugar into your brine can help balance flavors—but don't bother with other spices. "Salt and sugar are water soluble," Cox says. "Things like pepper are fat soluble so they won't dissolve in water," meaning their taste will be lost.

But no matter which bird or what method you choose, make sure you don't roast past an internal temperature of 165˚F. Because no brine can save an overcooked turkey.

This piece originally ran in 2017.

Why Your Cat's Tongue Is Nature's Perfect Hairbrush

iStock.com/takashikiji
iStock.com/takashikiji

A lick from a cat is a mixed blessing. On the one hand, cats don’t dole out affection to just anyone, so it’s a true compliment when they try to groom you. On the other hand, their tongues feel like sandpaper wrapped in barbed wire. Those sharp tongues are actually incredible tools, according to a new study published in Proceedings of the National Academy of Sciences. Their unique structure is very efficient at depositing saliva on cats' fur to help them clean themselves and keep cool. Researchers from Georgia Tech made the discovery using high-speed video, CT scans, and “grooming force measurements.”

Cats aren't just prettying themselves up when they spend all day grooming themselves, the study shows. (That’s not an exaggeration—house cats can spend up to a quarter of their waking lives grooming.) As they lick themselves, their tongues remove debris, fleas, and excess heat from their fur thanks to those sharp, curved spines—called filiform papillae—that are so unpleasant to feel on your skin.

A close-up image of a cat's tongue
Alexis Noel

These keratin-based filiform papillae have U-shaped hollows at their tips that allow cats to wick saliva from their mouths onto their fur, helping them regulate body temperature and cool down. Each of these papillae can carry one-tenth of an eyedropper’s worth of spit, half of which gets deposited on the fur. The papillae spread the saliva along the roots of each hair, allowing it to penetrate cats’ fur so that it can cool their skin. Saliva alone can provide 25 percent of a cat’s cooling needs, according to the study.

This useful adaptation isn’t limited to domestic cats. Researchers looked at tongue tissue from six different species—bobcat, cougar, snow leopard, tiger, and lion, in addition to house cats—and found similar structures.

As part of the study, the researchers also created a flexible “tongue-inspired grooming" (TIGR) brush with the help of 3D models of a house cat’s papillae. They found it was easier to clean than a typical human hairbrush—hair could be removed from it in one swipe, without the tweezers or other tools you need to get hair out of the stiff bristles of the typical hairbrush. (The wavy ridges on the roofs of cats’ mouths may do this job in the animals themselves.)

The brush has several potential uses. Because of its papillae-inspired structure, it could be used to apply liquids to cats’ skin. That could be helpful for applying topical medication, but it might also be a way to wash off some of the allergens they produce that bother humans. Potentially, there could be human uses for a papillae-like hairbrush in the future, too. You could imagine using it to brush styling products evenly through your hair, for instance. The researchers suggest the structure "may provide inspiration to soft robotics and biologically inspired technologies for sorting, cleaning, and depositing fluids into fur and arrays of flexible filaments."

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