Can Turtles Fly?

In the Midwest, where I grew up, April is when box turtles emerge from hibernation deep in the woods and crawl to less secluded areas to perform their summer activities. This transition often requires crossing country roads, and the turtles occasionally cause car accidents as drivers mercifully try to avoid hitting these armored critters.

What’s the nature of their armor? It comes in two major parts. The carapace is the domed upper shell and represents transformed ribs and vertebrae that have spread out and fused together. The plastron forms the flat “belly” and likely developed from an expanded breastbone and possibly from abdominal ribs. Abdominal ribs, known as gastralia, are present in modern-day crocodiles, alligators, and some lizards. Gastralia also strengthened the abdominal walls in many dinosaurs, including Tyrannosaurus rex.

Bony plates comprising the carapace (left) and plastron (right) of the desert tortoise (Gopherus agassizii). (Nevada State Museum.)
Apalachiosaurus with gastral basket (abdominal ribs). (Denver Museum of Nature and Science)

Covering the tightly interdigitated bony plates that constitute the plastron and carapace are shield-like osteoderms—bony deposits in the skin, from which turtles derive their patterned coloration. Osteoderms are not part of the skeleton but, nonetheless, make themselves available for fossilization and examination millions of years later. Consequently, we not only know about prehistoric turtles and their predecessors but also about armadillos (mammals), past and present, that also tote osteoderms.

Upper left: Osteoderms on Gargoyleosaurus parkinorum, 145 million years old. (Denver Museum of Nature and Science)
Lower left: Osteoderms (and skull) on a modern-day crocodile. (Museum and Art Gallery of the Northern Territory, Australia)Above:
Upper Right: The giant armadillo, Glyptodon, was 9 feet long and ranged over South American and lower North America, became extinct 11,500 years ago. (Tellus Museum of Science)
Lower Right: The extant nine-banded armadillo, Dasypus novemcinctus, is 30 inches long from tip to tail and is found in South, Central, and North America. (Museum of Osteology)

As beautiful and amazing as turtle shells are, they get really interesting when examined from the inside. Only the vertebrae in the neck and tail move on one other, while most of the spine and all the ribs are fused to the inner surface of the shell—a stiff back indeed. What astounds me and until recently has also confounded biologists is that a turtle’s shoulder blades are inside its rib cage rather than outside as they are on all amphibians, other reptiles (including birds), and mammals. Investigators have recently compared the embryologic development of mice, chicks, and turtles. All of these animals start out the same way, but then turtles experience an enfolding of the body wall, and the shoulder blades end up inside.

Cut-away specimens show shoulder blades (arrows) inside the rib cage and the mobile neck and tail bones.  (Above: French National Museum of Natural History. Below: Nevada State Museum.)

Despite the shell’s strength and its unique skeletal anatomy, a turtle typically comes out on the losing end of an encounter with an automobile, but not always. There are two reports of turtles being flipped into the air by a passing car and crashing through the windshield of a following vehicle. In both instances, the startled occupants and the turtles sustained only minor injuries. Way to go, turtle shells. This is yet one more reason to drive carefully.

Here are two more.

Galapagos Tortoise (Los Angeles County Museum of Natural History)
The largest turtle ever, Archelon ischyros, measured 11.5 feet head to tail and became extinct about 66 million years ago. Its spiky plastron is visible through the fenestrated carapace. (Yale Peabody Museum)

Whale Bones, Undergarments, and Valentine’s Day

Think of a bone. The image that usually comes to mind is a hard, white tube with knobby ends. In many instances, that is an accurate perception; but there are major exceptions that make bone even more interesting and valuable, especially for repurposing after the original owner passes on. A great example is a sperm whale’s jaw bone, which may be 25 feet long. Conical teeth the size of drinking glasses stud the forepart and often have been decorated with scrimshaw. Perhaps less well recognized is the multipurpose value of the hind part of the leviathan’s mandible, where it contacts the skull. There it is broad, flat, and thin and has been used for centuries for fabricating objects both functional and aesthetic. Today we might start a similar project using poster board or a sheet of plastic or canvas.

Sperm whale jawbones. Left, Harvard Museum of Natural History. Right, New Bedford Whaling Museum

Vikings were perhaps the first to take advantage of this smooth, durable crafting material and cut the jawbone into dragon-headed trays. Their purpose remains unknown. Speculation suggests that these plaques were food trays or cutting boards or even forms around which to wrap clothing to limit wrinkling. Inuits crafted jawbones into snow knives and used them to trim large blocks of snow that then fit snuggly together to form igloos.

Left: Viking plaque 8.7″ x 7.1″, British Museum. Right: Inuit snow knives, Smithsonian

Nineteenth century whalers were the hands-down champions at repurposing the sperm whales’ jaw bones. On their multiyear voyages, the seafarers had easy access to these bones, which would otherwise be discarded, and they had ample free time on their return trips from the whaling grounds to develop and improve their artistic skills.

In 1843, Joseph Bogart Hersey, third mate on the whaling schooner Esquimaux out of Providencetown, Massachusetts, wrote, “This afternoon we commenced sawing up the large whale’s jaws that we captured in company with [the schooner] Belle Isle on the 14th; the bone proved to be pretty good and yielded several canes, fids, and busks. I employed a part of my time in engrav[ing] or flowering two busks. Being slightly skilled in the art of flowering; that is drawing and painting upon bone; steam boats, flower pots, monuments, balloons, landscapes &c &c &c; I have many demands made upon my generosity, and I do not wish to slight any; I of course work for all.”

Herman Melville, in Moby-Dick (1851), noted, “… in general, they toil with their jack-​knives alone; and, with that almost omnipotent tool of the sailor, they will turn you out anything you please, in the way of a mariner’s fancy.”

Left to right: ditty box, work basket, violin, chair, all from New Bedford Whaling Museum. Right: humidor, Pinterest.

The purposes for most of the crafted objects are immediately obvious, but not so for semi-rigid strips that lonely whalers meticulously inscribed and gave to their loved ones on their return home. These were busks, which were inserted into a pocket on the front of nineteenth century corsets to keep undergarments upright and straight. Held close to his loved-one’s heart, the busk also served as a remembrance of love and devotion during the seafarer’s next long absence.

New Bedford Whaling Museum

In modern times, gifts of hand-inscribed busks have morphed into ones of roses and chocolate as expressions of Valentine sentiments. Yet they are not nearly as personal, endearing, or enduring as whalebone busks. Could they make a comeback if corsets again became fashionable?

Happy Valentine’s Day. Please encourage your Valentines and social media contacts to subscribe to

Assorted busks, New Bedford Whaling Museum

Holiday Shopping Guide for Books About Bone

You can never go wrong considering “bone” when choosing holiday gifts for the discerning and hard-to-please. Past December posts have described gifts from the ridiculously economical (Holiday Gift Guide for Frugal Bone Lovers) to the breathtakingly expensive (Extravagant Gifts for Bone Lovers). This year’s recommendations focus on books.

Written in Bone. Hidden Stories in What We Leave Behind. Author Sue Black, 2020.

Sue Black, a British forensic anthropologist and anatomist, starts at the skull and ends 10 chapters later at the toes. She mixes interesting facts about how each of the bones in our skeleton forms and what they can (or cannot) reveal about the lives of the original owners. She makes it clear that forensic pathologists and forensic anthropologists lead grim lives. The former are called on to determine the cause of death that occurred in recent times. The latter are experts in examining remains regardless how old and opine regarding their human vs. non-human origins, sex, age, stature, and diet. The author explains how this is possible and enriches the descriptions with examples from her own worldwide experience. Some of the cases involve fingerprints, hair, teeth, and other non-osseous clues. At first, I was miffed by this apparent diversion from the title, Written in Bone; but when I accepted the title as an eyecatcher, then the subtitle accurately describes the book’s contents. This book is not for the faint of heart. Some of her findings and descriptions are outright grisly and macabre. If you like CSI, however, you fill find Black’s writing informative, engaging, and at times even humorous.

Fossil Men, The Quest for the Oldest Skeleton and the Origins of Humankind. Author Kermit Pattison. 2020.

Do your gift recipients take an interest in the study of ancient humans and their predecessors? Would they like to read about scientists’ interpersonal spats mixed in with the dangers and frustrations of Ethiopian tribal warfare and government instability? Would a non-fiction book that at times reads as if it had to be fabricated ring their bell? If so, this book might be a good pick. It recounts the ever-changing and at times infuriating mix of fossils, territory, research money, and Ethiopian governmental bureaucracy when paleoanthropologists were seeking and finding humanoid fossils older than Lucy, dated at 3.2 million years. At times Pattison goes into far more detail describing and comparing the lumps and grooves on individual bones than most general readers can manage, but they can scan these sections and still come away with a respect for the scientists who sweat their summers away in sand pits half way around the world with paintbrush and trowel in hand.         

Bones. Recipes, History, and Lore. Author Jennifer McLagan, 2005.

Can you believe that there is an entire cookbook devoted to bones? Well, at least to the meat with the bones still attached. The author, a professional cook and food writer, makes a strong case that beef, veal, pork, lamb, poultry, fish, and game taste better when cooked on the bone. Unfortunately, we often sacrifice taste, texture, and presentation for the sake of convenience and choose boneless cuts. To remedy these gastronomic oversights, McLagan devotes individual chapters to each source of meat and describes both simple and complex preparations where the intrinsic flavors of the bones greatly enhance the dishes. Does an olive-crusted lamb rack or crown roast of pork sound good? Maple tomato glazed ribs? Coconut chicken curry? Halibut steaks with orange cream sauce? Duck legs with cumin, turnips, and green olives? Roasted marrow bones with parsley salad? The book is peppered with numerous full-color photographs of the final presentations, which makes the work suitable for residence on the coffee table when it is not at work in the kitchen. Should dinner conversation regarding the meal itself finally wane, McLagan salts the book with interesting facts including wishbone lore, fish bone superstitions, and interpretation of bones appearing in dreams. This book is probably not the best gift choice for vegetarians.

Bones, Inside and Out. Author Roy A. Meals, MD. 2020.

For readers who may not want to read a whole book about forensic anthropology, paleoanthropology, or cooking, but who would like broad information about the world’s best building material, this compendium is the obvious choice. The author describes the composition and structure of bone in nontechnical terms and demystifies how bones form, grow, break, and heal. He highlights medical innovations from the first X-rays to advanced operative techniques and the orthopedic giants who developed them. Meals goes on to describe the diverse roles bone has played in in the story of life and human culture, from paleontology and anthropology to religion and literature, including Adam’s rib and Yorick’s skull. Overall, Bones is informative, approachable, and entertaining, and it now available in paperback. Since you have read this far, the author will send a signed bookplate to giftees of your choice. Just click on “contact” in the upper right corner of the web page and indicate the recipients’ names and snail mail addresses. Each plate will arrive in early January so as not to spoil the recipients’ surprise and delight when you give them this treasure during the upcoming holidays. 

Happy Holidays!

A Bone Lover’s Thanksgiving Nightmare

Shortly after spending our first Thanksgiving together nearly 50 years ago, I surprised my wife. It wasn’t that she saw me boiling the denuded turkey carcass, but rather that I ignored the resultant stock and was attempting a skeletal reassembly of the bare bones. My passion for bones has only increased since then, a passion that she begrudgingly accepts, especially every November.

Around Thanksgiving dinner tables everywhere, faces should brighten when bone lovers direct the conversation from politics and sports to the rich cultural history of wishbones. (See previous blog post Twelve No-Fail Conversation Starters Regarding Wishbones.) Should that conversation wane, a discussion of transforming a turkey’s wing bones into trumpet-like turkey callers will undoubtedly rouse diners again from tryptophan lethargy. (See previous blog post It Takes a Turkey to Call a Turkey.)

Consider then the horror of having to endure a boneless Thanksgiving. The modern roots of this nightmare originated in the 1980’s, maybe from the kitchen of Cajun chef Paul Prudhomme. The NFL TV commentator John Madden extolled this unusual preparation’s tasty virtues widely during his Thanksgiving Day football broadcasts. Not only have all the bones except from wings and legs been extracted from the turkey, its floppy remains are then stuffed with a completely deboned duck, which has been previously stuffed with a completely deboned chicken. The combo becomes a “turducken”, a compression of the words turkey duck chicken. Three fowls down, no wishbones to go.

Before I might campaign for an outright ban of such an osseous sacrilege, I decided to know my enemy and try turducken. YouTube videos describe the required ghastly serial deboning and reassembling, which also involves stuffing any interior voids with cornbread and, according to one’s interest in recreating Cajun authenticity, adding some andouille sausage or crayfish. More interested in the result than the process, I turned to Amazon. Over the next two days, my turducken flew from Louisiana to Los Angeles surrounded by dry ice and Styrofoam.

It took three days to thaw in the fridge. I decided to roast the eleven-pound mass on the barbeque rather than in the oven, which might again risk marital harmony. After about 6 hours at 325oF it was approaching the requisite 165oF in the deepest reaches of the chicken, and another 30 minutes with chimera uncovered brought its skin to a golden brown. My wife and I agreed that it smelled good, perhaps partly because it was now two hours after our usual dinner time.

It sliced like a loaf of bread, far easier than carving a conventional turkey, particularly so because I didn’t have to work the knife carefully around any skeleton, including precious wishbones. The turducken tasted good. Each bite was a separate surprise because, somewhat by sight and certainly by taste, the roasting juices had blurred demarcations between the tur, duc, ken, stuffing, and sausage. But I guess that’s the whole point.

Would I do it again? Yes, but only if the fileted bones came along in a separate packet. Then I could sleep blissfully.

Happy Thanksgiving!

A Plea for Anatomical Correctness at Halloween–With Reader Updates.

Last October I blogged about Halloween costumes and the importance of being anatomically correct when stepping out as a skeleton.  I am sure that bone lovers everywhere are equally tetchy about other anatomically incorrect Halloween accoutrements, because if the manufacturer has taken liberties with anatomical accuracy, we would have to question both their world view and commitment to all-around quality.

Let’s start with a biology refresher. Worms, obviously, do not have bones, but neither do some critters that crunch when stepped on. For instance, insects, spiders, and crustaceans (lobsters, shrimp, etc.) have exoskeletons made from thin, waterproof, semirigid shells of chitin. This certainly is a successful means of protection and support, but it presents a problem when the owners want to expand, They have to crawl out of their skeletons and grow a new ones. In the interim, they are vulnerable to predation and may turn into soft-shelled crab sandwiches. Clams, snails, scallops, and oysters avoid this perilous transition by merely making regular additions to the edges of their calcium-based exoskeletons and gradually enlarge them without having to leave home.  

Animals with spines (vertebrates) have endoskeletons. For sharks, that means rubbery cartilage (the same material that constitute our noses and external ears). Bony fish, and amphibians (frogs, salamanders, etc.), reptiles including birds, and mammals (including us) have skeletons made of rigid, calcium-laden bone. Its durability allows bone to preserve evidence of formerly living animals, which is integral to the concept of Halloween.

After this brief biology overview, you can probably spot what is wrong in these pictures.

Look at the ears on the dog and horse. They are as out of place on a skeleton as a stocking cap or moustache would be. Worse, however, are the lobster and spider. My spine shudders to see them represented with bony endoskeletons rather than with their naturally occurring chitin armor.

On viewing the original version of this post earlier today, sharp-eyed bone lovers also identified several disturbing errors in skeletal anatomy on the human in the foreground. The lower legs are on the wrong side. (The thicker bone, the tibia, should be on the inside of the thinner bone, the fibula, on the outside.) The right hip is dislocated, which may account for the pained expression on the skeleton’s face. It looks like there are eight sets of ribs rather than twelve. At least the human skeleton is not sporting bone ears as do the horse and dog.

As you come across Halloween decor this week, please document other bone infractions and send photos to  I will notify the Bone Police immediately. I know, it’s frightful, but then, that’s what Halloween is about.


And if you find Halloween’s disrespect of bones irksome, it gets worse. Watch for A Bone Lover’s Thanksgiving Nightmare, coming soon.


For Halloween and all other special occasions, no gift is in finer taste or will be more appreciated than a copy of Bones, Inside and Out, now also available in Russian.

WW Norton   Amazon    Apple Books   Barnes and Noble   Books-a-Million   Bookshop   Hudson   IndieBound   Target   Walmart

Fossil Men

Have you exhausted your “to-read” pandemic book list? Do you take an interest in the study of ancient humans and their predecessors? Would you like to read about scientists’ interpersonal spats mixed in with the dangers and frustrations of Ethiopian tribal warfare and government instability? Does a non-fiction book that at times reads as if it had to be made up ring your bell? If so, Fossil Men, The Quest for the Oldest Skeleton and the Origins of Humankind by Kermit Pattison (Willliam Morrow, 2020) might be a good pick.     

Early on, Pattison describes paleoanthropology: “Fossils, territory, and money were the raw materials of the discipline.” Following the 1974 discovery of “Lucy”, a 3.2-million-year-old pre-human skeleton in Ethiopia, teams of paleoanthropologists intensified their search for even older skeletons that could fill in and confirm or deny prevailing theories about the timing and pattern of human evolution. Lucy clarified that our ancestors first came out of the trees and walked upright, and then later they developed larger brains. But this information pushed farther back in time the questions of when and how. Older fossils would be enlightening.

Regarding territory, the Great Rift Valley slashes through Tanzania, Kenya, and Ethiopia. The Rift is prime fossil-hunting territory. Africa is generally considered to be the home of pre-human forms, and this long valley provides ample opportunity for bones to get washed into the basin, buried, fossilized, and then possibly exposed millions of years later. Lucy was discovered in Ethiopia; and further south in Tanzania Mary Leakey and her team discovered fossilized footprints of a humanlike creature who walked upright, 500,000 years before Lucy. How long before that had ape-like creatures abandoned knuckle walking?

After these discoveries, the Great Rift Valley, and especially its portion in northern Ethiopia, was an obvious place to intensify the search for older fossils, but this was complicated by territorial conflicts of two sorts. Warring tribes ranged over the area and were wary, and at times overtly hostile, to one another and even more so to khaki-clad foreigners driving Jeeps.

The other conflict simmered in the government offices in Addis Ababa after the military overthrow of long-time Ethiopian emperor Haile Selassie in 1974. The Ethiopians were justifiably proud of their country’s recognition as the location of Lucy’s discovery and her role in the story of human evolution. They were miffed, however, that the limelight focused on the foreign scientists and their inclinations to remove these world-heritage artefacts from their native land. These territorial issues were compounded further by changes in administrative leadership and some backscratching regarding allocation of territories for fossil-hunting rights to one team over another. Sometimes a team would sit in Addis Ababa for weeks waiting for authorizations to be signed. At times, the fossil fields were closed to exploration for years, perhaps on no more than a whim of a local official.

Regarding money, the expeditions, which were mostly from America, lasted four to five months and involved scores of scientists, grad students, camp workers, and guards. The fossil fields were a two-day drive from Addis Ababa and entirely remote; so electricity generation, water purification, and sanitation systems all required attention. Detailed casts were made of the recovered fossils that were not permitted to leave Ethiopia. Other fossils were smuggled out. At home, the investigators could study the material but needed salary support to do so. The National Science Foundation was instrumental in providing competitive grants, but some of the teams had sufficiently alienated one other regarding disputed claims that impartial reviewers of grant proposals were sparse to non-existent. Leaders in the field sometimes went unfunded and had to pare down their ambitions and also seek private support.

In addition to issues of fossils, territory, and funding, the involved paleoanthropologists seemed to have big egos, at least the ones who tended to make themselves known. Perhaps this is not surprising since they sweat for months with their noses pressed to the sand. They get excited when they discover even a solitary tooth, from which they claim, with some authority apparently, that they can identify the species of its owner.

Ardipithecus ramidus, courtesy T. Michael Keesey, Wikipedia

Infighting was further compounded by the fact that the team who identified a 4.2-million-year-old possible human predecessor, Ardipithecus ramidus, nicknamed Ardi. The discoverers announced their find but did not let other scientists examine the fossils, nor did they report their analysis in the peer-reviewed scientific literature for 15 years. In the meantime, however, the finders infuriated other paleoanthropologists at meetings and in publications by discounting competing teams’ findings based on their own, but unpublished, discoveries.

The book was meticulously researched over a decade and is based on interviews with many of the principle … um … characters. Photographs of the digs, the diggers, and their finds are enlightening. Sometimes the perseverations over the meaning of an individual groove or shape of a facet on a single hand or foot bone become tediously long, especially in a book for lay readers and when the details of interest were not illustrated. You can scan those machinations without missing the book’s gist. After you’ve read Fossil Men, let me know what you think.

Related posts

Lucy, where are the rest of your bones?

Genuine hate produced the Bone Wars.

Moose Musings

Now that we are getting out and socializing face-to-face, it is important to have conversation topics beyond what books we read during lockdown and which vaccine we received. Should the topic of moose arise, here are some facts about their antlers suitable for enriching the discussion.

Moose are a species of deer. All species in the deer family have antlers, which they shed annually. Except for caribou, only the males of each species sport such racks.  (Antelope, bison, sheep, and cattle are not deer, and they have horns, which they keep through life.)

Both antlers and horns are bone. When antlers mature each fall, the velvety covering of skin falls off, and the bone is exposed. For horns, the bone is always covered with a thin layer of keratin—the same material comprising fingernails.

Moose are the largest living species in the deer family, with bulls weighing up to 1500 pounds. The antlers account for 80 of those pounds on the big guys.

The word moose is derived from moosh (stripper and eater of bark), first used by the Innu people of Quebec. Moose eat 35 pounds of twigs and bark every day in the winter and twice that in the summer. A fourth of the energy they consume is used to support antler growth.

Moose antlers are by far the fastest growing mammalian tissue, going from zero in March to full grown in less than five months, sometimes gaining a pound a day.

They can grow that quickly because the initial thick velvety covering is laden with nutrient-supplying blood vessels. By fall, when it is time to impress the ladies, the velvety layer comes loose and falls off, but it may dangle temporarily in entirely unappealing festoons before a bull can look and feel his best.

A large rack apparently impresses the cows and intimidates the bullies, with whom the bull may occasionally spar to demonstrate dominance. Occasionally the competitors lock antlers and can’t disengage, causing them to stare directly at each other while they both starve to death.

Moose in their prime, 5-8 years old, sport the largest racks, which will include portions which extend over their brow and protect the eyes from gouging. Younger and older males get by with less.

The flat plate of antler bone is called the palm, and the extending tines are called points. The beam is the stalk that connects the antler to the skull. This terminology is important to trophy hunters. You can impress one by asking how the rack displayed in their man cave (ahem, person cave) scores on the B & C scale.

In 1887 Theodore Roosevelt founded the Boone and Crockett Club (yes, named for Daniel and Davy). It is North America’s oldest wildlife and habitat conservation organization. For rating moose-antler grandeur, the B & C score combines the spread (the record is 6 feet, 4 inches), palm length, palm width, beam circumference, and the number of points into a single brag-rights number.

Diminishing hours of daylight in late fall cause moose testosterone levels to drop, which causes their antlers to do the same in December or January. The abandoned antlers are called shed, and a late wintertime activity for outdoorspeople it to tromp moose territory hunting shed. This is illegal in some states for at least portions of the year in order to leave the habitat undisturbed for a while.

The ethics of shed hunting include not harassing a bull that is missing one antler while hoping that he will drop the other one in your presence. Sounds sensible, considering that a moose can run toward you at 35 miles per hour as easily as it can run away.

A shed sells for $4 to $12 per pound depending on the degree of weathering and damage. The antlers are valued by furniture, chandelier, and cutlery makers as well as by artists and dog chew manufacturers. Rodents and other small creatures also like shed. For them, it is a great source of calcium and other vital nutrients.

The palmar grooves trace the paths of the now absent arteries

I just returned from a fabulous adventure trip in Alaska, where moose fences protect the major highways. Moose crossing signs abound, even in Anchorage. Alas, I did not see a moose, and I posed only momentarily with a shed. I did, however, collect some great dinner party facts. Now you have them too. 

Photo credits: April July August and September

Patēr or faeder? Jawbone size affects speech and pronunciation of “Fathers’ Day”.

When I was a teenager, a dentist extracted my unemerged wisdom teeth. He said they were impacted and were crowding my other teeth. Recently I found out why. It was a childhood of not chewing forcefully enough, which caused my jawbone to slightly undergrow, enough that there was no room left to accommodate my third molars, which are the last ones to erupt during growth (a dental version of musical chairs). Studies show that at least three-fourths of modern humans are similarly affected.

courtesy Coronation Dental Specialty Group, Wikimedia Commons

Our fossil ancestors did not have impacted wisdom teeth, and their occlusion was dead on—their upper and lower front teeth contacted each other precisely, which allowed for efficiency in cropping twigs and gnawing gristle off bones. These hunter-gatherers then had to chew long and hard to make these raw, tough foods digestible. Their progeny eventually quit the nomadic life and changed to a diet of roasted meat and boiled grain. Since as children these “civilized” folk did not have to gnaw and grind forcefully to nourish themselves, they developed overbites, because their jawbones failed to achieve their full growth potential. Apparently a modern diet of mashed potatoes, ground beef, boiled peas, and ice cream is not conducive to the development of a jawbone capable of comfortably housing all of our 32 teeth.

Multiple observations support this use-it-or-lose-it concept. As far back as 1871, Charles Darwin in his book, The Descent of Man, made the association between oral stress and jaw size. In recent times, anthropologist Robert Corruccini noted that elders in rural Kentucky, who grew up eating hard-to-chew foods, had better bites, despite the near absence of professional dental care, than did younger residents who grew up eating more processed foods. He observed similar bite differences in the Pima Indians before and after they had access to grocery stores and in rural and urban dwellers in India who ate diets of hard millet and tough vegetables vs. soft bread and lentils, respectively. Studies on mice (see comparative images) and monkeys have also indicated that soft diets result in smaller jaws.

Does this make you want to begin eating bark and jerky? If you are out of high school, sorry, it is too late. Like me, you can see your dentist or accept having crooked teeth, an overbite, or both. But the overbite does offer an advantage—the ability to efficiently make words starting with “f” or “v”. The linguists call these sounds labiodentals, and computer modeling says that they are 29% easier to say with an overbite than with edge-to-edge occlusion. About 4000 years ago, development of an overbite among our gruel-sipping ancestors helped spur the diversification of languages in Europe and Asia. A linguist has suggested that in ancient Rome and India using labiodentals was a status symbol, indicating wealth associated with a soft diet. Even for the poor about 1500 years ago, the Proto-Indo-European patēr, which carried over into Latin, changed to the Old English faeder. Today, labiodental consonants are present in 76% of Indo-European languages.

Perhaps I am belaboring the obvious, but as a bone lover I must extol bone. Isn’t it amazing that bone cells can respond to the presence or absence of mechanical stresses encountered during chewing and that leads to job security for dentists and to the sounds we make when speaking? Happy Fathers’ Day.


Conserving Old Bone

I recently zoomed with two fellow bone lovers, both of whom have markedly elevated my respect for bones displayed in museums, to which I am gravitationally attracted.  

Mariana Di Giacomo is a natural history conservator at the Yale Peabody Museum of Natural History, and Melissa King is a preventive conservator currently on fellowship at the Smithsonian Institution. As they explained to me, a lot more than meets the eye goes into display and protection of museum fossils and bones, which are used both for education and research.

T rex vertebrae on plaster mount under review by conservator Mariana Di Giacomo.
Tyrannosaurus rex, USNM 555000. Courtesy U.S. Army Corps of
Engineers, Omaha District and The Museum of the Rockies, Montana State
University. Photo by Kate D. Sherwood, Smithsonian.

For instance, should a bone that was broken when discovered be glued back together? Doing so keeps the two parts from getting misplaced and demonstrates more closely its real-life self, but reassembly precludes access to the bone’s interior for any analysis–perhaps today for DNA or protein, tomorrow for some presently unknown test. As a compromise between reattaching the fragments and leaving them dissociated, they may make a mount that supports the pieces in their original orientation but without physically joining them.

Superglue or Gorilla Glue? No and no, emphatically. Conservators use B-72 on bone, as they do on ceramic and glass. It is a thermoplastic, non-yellowing, durable resin. They also use B-72 as a means to permanently and non-destructively label bones and fossils. They paint on a stripe of resin, hand write the identification with non-penetrating ink, and then protect the ID with another layer of B-72.

Mariana rolled her eyes when I asked what mistakes had been made in the past. With good intentions, fossils and bones have been sealed with wax, varnish, and other coatings that degrade in unsuspected ways and greatly damage the specimen’s appearance and study value. Without any surface treatment, bones and fossils on display weather away far more slowly than they would at their original discovery site; but museums contain their own destructive perils, which include sunlight, fluctuating temperature and humidity, and dust. Conservation of biological specimens parallels that of oil paintings and is approached with similar delicacy. Then before a specimen goes into a display case, the materials and coatings comprising the case are tested for any off-gassing that could damage the item. Should the display case be air-tight to prevent exposure to environmental pollutants such as acetic acid, which will dissolve bone? Or would sealing the case cause its own set of problems?

Musical Instrument Museum, Phoenix

Bone that has been repurposed to make or decorate weapons and musical instruments also creates problems, particularly when it has been inset into other materials, for instance wood, which has its own conservation demands. Then for leather, feathers, cloth and other biologically derived materials embellishing crafted bone artefacts, protection from insects and vermin is key. Conservators by necessity become verminologists, learn the life cycles of these spoilers, and apply integrated pest management, which consists of various biologic, physical, and chemical means for protecting the collection while minimizing overall health and environmental issues. A non-living menace is dust, much of which is partially decomposed animal matter and which is great fodder for vermin.

Bill Simpson at the Field Museum giving Sue a periodic air bath.

Gigantic skeletal specimens, too large to encase, need to be delicately dusted from time to time; but particularly when they are extraordinarily tall or suspended from the ceiling, regular housecleaning becomes problematic. It might be easier to routinely display skeletal replicas and take them down for a bath periodically, but museum visitors like to see the real specimens. This poses its own set of problems because assembling fossil bones into a lifelike stance requires heavy metal supports, and the current trend is to mount specimens such that any single bone can be removed for analysis without disassembling the entire display. This, of course, makes the support system far more complex and visible.

Conversely, displaying replicas and leaving the real specimens in the storeroom is not without risk either. The original pieces, if not carefully labelled and catalogued, can get separated, misplaced, damaged, or lost, even if carefully protected in padded boxes inside of cabinet drawers. Of course, that degree of protection is not possible for fossils that are measured in feet and in hundreds of pounds.

Overall, my conversation with Mariana and Melissa heightened my appreciation for the care that goes into bones displayed and preserved in museums. Fine art conservation and restoration make the news from time to time. Bone deserves (and is receiving) the same level of care and should be equally celebrated. 


Follow up on the recent post: Marking Time in Prague. A reader commented that the Prague Old Town Square in front of the ancient clock was the local pickpockets’ favorite location. I can imagine: everybody relaxed, looking up, likely getting jostled a bit, robbed–another peril avoided by traveling virtually!

Hyoid Howling

Andreas Vesalius: De Humani Corporis Fabrica Libri Septem (On the fabric of the human body), 1543

Out of the roughly 206 bones in our body, the hyoid bone is the only one that is entirely separated from the rest of the skeleton. Vesalius in the 16th century recognized its isolation and depicted the hyoid resting on the plinth like a set of false teeth. Being U-shaped, it is appropriately named after the Greek letter upsilon. The hyoid bone resides immediately under the jawbone, just above the thyroid cartilage (Adam’s apple in men). Here 12 muscles attach that are critical for swallowing and vocalizing. In this well-protected position, it doesn’t get much notice and is rarely broken. Strangulation is the exception, so the coroner in your detective novel might want a look at it.

In humans, and uniquely so, the hyoid bone is moveable, which has been one of the evolutionary changes important for speech development. Its mobility, however, also contributes to obstructive sleep apnea. As the attached base-of-tongue muscles fall backwards in relaxation, they narrow the airway in the throat. Otolaryngologists counter this by drawing the hyoid approximately an inch forward and tethering it with strong sutures either to the inside of the jawbone or to the top edge of the thyroid cartilage. I would think that this might affect speech or swallowing, but the research papers say otherwise.  

Don’t confuse the hyoid bone with the wishbone, which is present in some birds and their dinosaur relatives. The wishbone is farther down the neck, is a fusion of those animals’ collar bones, and contributes to efficient flying in some species. (See previous post: Twelve No-Fail Conversation Starters About Wishbones.) By contrast, all vertebrate animals have a hyoid bone, although it varies widely in shape and function. Here are two examples.

The hyoid bone helps a woodpecker pound its beak 22 times a second, 12,000 times a day, without apparently giving itself headaches. The beak is a bit flexible, which absorbs some of the shock, as does a thick pad of spongy bone that separates the beak from the skull. The hyoid bone handles the rest. It starts in the neck, like in the rest of us, but then curls around behind and over the skull to attach next to a nostril, thus bypassing the brain. It is thin and fragile looking.

Not so for the endangered howler monkey. Its hyoid bone is about the size and general shape of a 4-ounce, round-bottomed measuring cup. That is almost half the size of the monkey’s skull. The hyoid is instrumental in the howler’s ability to project its voice two miles.

Given the relative numbers of howlers and humans, it’s good that we are not so well-voiced.    

Published in abbreviated form in NYT Book Review Letters, March 21, 2021