Why Don’t Bugs Eat People’s Bones?

ledwell/iStock via Getty Images
ledwell/iStock via Getty Images

In her new book, Will My Cat Eat My Eyeballs: Big Questions from Tiny Mortals About Death, mortician and best-selling author Caitlin Doughty answers real questions she's received from kids about death, dead bodies, and decomposition. In the following excerpt, she describes why the creatures that consider skin and organs a tasty snack just don't feel the same way about our skeletons. (It's nothing personal.)

It’s a lovely summer day and you’re having lunch in the park. You bite into a fried chicken wing, munching on the crispy skin and juicy flesh. Is your next move cracking into the bones, crunching them like the giant in “Jack and the Beanstalk”? Probably not.

If you yourself wouldn’t eat a pile of animal bones, why would you expect a beetle to show up and eat your bones? We expect too much from necrophages, the unsung heroes of the natural world. They are the death eaters, the organisms that fuel up by consuming dead and rotting things—and bless their hearts! Imagine, for a moment, what the world would look like without the assistance of the consumers of dead flesh. Corpses and carcasses everywhere. That road kill? It’s not going anywhere without the help of necrophages.

Necrophages do such a good job getting rid of dead things that we expect them to perform miracles. It’s like how if you do too good a job of cleaning your room, then your mom will expect perfection every time. Better to not set expectations so high. It’s just not worth the risk.

The corpse-nosher ranks are filled with diverse species. You have vultures, swooping down for a roadside snack. You have blowflies, which can smell death from up to 10 miles away. You have carrion beetles, which devour dried muscle. A dead human body is a wonderland of ecological niches, offering a wide range of homes and snacks for those inclined to eat. There are plenty of seats at death’s dinner table.

Remember the dermestid beetle? The helpful cuties we’d enlist to clean your parents’ skulls? Their job is to eat all the flesh off without damaging the bone. Let’s be clear: we don’t want them to eat the bone. Especially because other methods of flesh removal (like harsh chemicals) will not only hurt the bones, but might damage certain types of evidence, like marks on bones, which could be useful in criminal investigations. That’s why you bring in a colony of thousands of dermestids to do the dirty work. Plus, while you were over here complaining that they don’t eat enough bones, the beetles were also eating skin, hair, and feathers!

All right, but to your question: why don’t they eat bones, too? The simple answer is that eating bones is hard work. Not only that, but bones are not nutritionally useful to insects. Bones are mostly made of calcium, something insects just don’t need a lot of. Since they don’t need much calcium, insects like dermestids haven’t evolved to consume it or desire it. They’re about as interested in eating bones as you are.

But, here’s a dramatic twist: just because these beetles don’t usually eat bone doesn’t mean they won’t. It’s a cost-reward thing. Bones are a frustrating meal, but a meal is a meal. Peter Coffey, an agriculture educator at the University of Maryland, told me how he learned this firsthand when he used Dermestes maculatus to clean the skeleton of a stillborn lamb. Adult sheep bones are robust, “but in fetuses and newborns there are several places where fusion is not yet complete.” When he removed the lamb bones after the beetles finished cleaning them, “I noticed small round holes, about the diameter of a large larva.” It turns out beetles will go after less dense, delicate bones (like those of the stillborn lamb), but, Peter says, “there has to be a perfect storm of good environmental conditions and poor food availability before they’ll resort to bone, which would explain why it’s not more commonly observed.”

So, while dermestids and other flesh-eating bugs do not usually eat bone, if they get hungry enough, they will. Humans behave the same way. When Paris was under siege in the late 16th century, the city was starving. When people inside the city ran out of cats and dogs and rats to eat, they began disinterring bodies from the mass graves in the cemetery. They took the bones and ground them into flour to make what became known as Madame de Montpensier’s bread. Bone appetit! (Actually, maybe don’t bone appetit, as many who ate the bone bread died themselves.)

It seems like no creature out there wants to eat bone, really prefers bone. But wait, I haven’t introduced you to Osedax, or the bone worm. (I mean, it’s right there in the name, people. Osedax means “bone eater” or “bone devourer” in Latin.) Bone worms start as tiny larvae, floating out in the vast blackness of the deep ocean. Suddenly, emerging from the void above is a big ol’ dead creature, like a whale or an elephant seal. The bone worm attaches, and the feast begins. To be fair, even Osedax don’t really devour the minerals in the bone. Instead, they burrow into the bone searching for collagen and lipids to eat. After the whale is gone, the worms die, but not before they release enough larvae to travel the currents waiting for another carcass to comes along.

Bone worms aren’t picky. You could throw a cow, or your dad (don’t do that), overboard and they’d eat those bones, too. There is strong evidence that bone worms have been eating giant marine reptiles since the time of the dinosaurs. That means the whale eaters are older than whales themselves. Osedax are nature’s peak bone eaters, and they’re even sorta nice to look at, orangey-red floating tubes covering bones like a deep-sea shag carpet. Pretty amazing, given that scientist didn’t even know these creatures existed until 2002. Who knows what else is out there in the world, devouring bone?

The cover of Will My Cat Eat My Eyeballs: Big Questions from Tiny Mortals About DeathW.W. Norton

Reprinted from Will My Cat Eat My Eyeballs: Big Questions from Tiny Mortals About Death by Caitlin Doughty. Text copyright (c) 2019 by Caitlin Doughty. Used with permission of the publisher, W. W. Norton & Company, Inc. All rights reserved.

10 LEGO Sets For Every Type of LEGO Builder 

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Amazon

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If you’re looking for a timeless gift to give this holiday season, look no further than a LEGO set. With kits that cater to a wide age range—from toddlers fine-tuning their motor skills to adults looking for a more engaged way to relax—there’s a LEGO set out there for everyone. We’ve rounded up some of our favorite sets on Amazon to help you find the LEGO box that will make your loved one smile this year. If you end up getting one for yourself too, don’t worry: we won’t tell.

1. Classic Large Creative Gift Box; $44

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You can never go wrong with a classic. This 790-piece box contains dozens of types of colored bricks so builders of any age can let their inner architect shine. With toy windows, doors, tires, and tire rims included in addition to traditional bricks, the building possibilities are truly endless. The bricks are compatible with all LEGO construction sets, so builders have the option of creating their own world or building a new addition onto an existing set.

Buy it: Amazon

2. Harry Potter Hogwarts Express; $64

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Experience the magic of Hogwarts with this buildable Hogwarts Express box. The Prisoner Of Azkaban-inspired kit not only features Hogwarts's signature mode of transportation, but also Platform 9 ¾, a railway bridge, and some of your favorite Harry Potter characters. Once the train is built, the sides and roof can be removed for play within the cars. There is a Dementor on board … but after a few spells cast by Harry and Lupin, the only ride he’ll take is a trip to the naughty list.

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3. Star Wars Battle of Hoth; $160

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Star Wars fans can go into battle—and rewrite the course of history—by recreating a terrifying AT-AT Walker from the Battle of Hoth. Complete with 1267 pieces to make this a fun challenge for ages 10 and up, the Walker has elements like spring-loaded shooters, a cockpit, and foldout panels to reveal its deadly inner workings. But never fear: Even though the situation might look dire, Luke Skywalker and his thermal detonator are ready to save the day.

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4. Super Mario Adventures Starter Course; $60

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Kids can play Super Mario in 3D with LEGO’s interactive set. After constructing one of the courses, young designers can turn on the electronic Mario figurine to get started. Mario’s built-in color sensors and LCD screens allow him to express more than 100 different reactions as he travels through the course. He’ll encounter obstacles, collect coins, and avoid Goomba and Bowser to the sound of the Mario soundtrack (played via an included speaker). This is a great gift for encouraging problem-solving and creativity in addition to gaming smarts.

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5. Gingerbread House; $212

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Gingerbread houses are a great way to enjoy the holidays … but this expert-level kit takes cookie construction to a whole new level. The outside of the LEGO house rotates around to show the interior of a sweet gingerbread family’s home. Although the living room is the standout with its brick light fireplace, the house also has a kitchen, bedroom, bathroom, and outdoor furniture. A LEGO Christmas tree and presents can be laid out as the holidays draw closer, making this a seasonal treat you can enjoy with your family every year.

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6. Elsa and Olaf’s Tea Party; $18

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LEGO isn’t just for big kids. Toddlers and preschoolers can start their LEGO journey early by constructing an adorable tea party with their favorite Frozen characters. As they set up Elsa and Olaf’s ice seats, house, and tea fixings, they’ll work on fine-motor, visual-spatial, and emotional skills. Building the set from scratch will enable them to put their own creative spin on a favorite movie, and will prepare them for building more complicated sets as they get older.

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7. Collectible Art Set Building Kits; $120

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Why buy art when you can build it yourself? LEGO’s Beatles and Warhol Marilyn Monroe sets contain four options for LEGO art that can be built and displayed inside your home. Each kit comes with a downloadable soundtrack you can listen to while you build, turning your art experience into a relaxing one. Once you’re finished building your creation it can be exhibited within a LEGO brick frame, with the option to hang it or dismantle it to start on a new piece. If the 1960s aren’t your thing, check out these Sith and Iron Man options.

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8. NASA Apollo Saturn V; $120

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The sky (or just the contents of your LEGO box) is the limit with LEGO’s Saturn V expert-level kit. Designed for ages 14 and up, this to-scale rocket includes three removable rocket stages, along with a command and service module, Lunar Lander, and more. Once the rocket is complete, two small astronaut figurines can plant a tiny American flag to mark a successful launch. The rocket comes with three stands so it can be displayed after completion, as well as a booklet for learning more about the Apollo moon missions.

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9. The White House; $100

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Reconstruct the First Family’s home (and one of America’s most famous landmarks) by erecting this display model of the White House. The model, which can be split into three distinct sections, features the Executive Residence, the West Wing, and the East Wing of the complex. Plant lovers can keep an eye out for the colorful rose garden and Jacqueline Kennedy Garden, which flank the Executive Residence. If you’re unable to visit the White House anytime soon, this model is the next best thing.

Buy it: Amazon

10. Volkswagen Camper Van; $120

Amazon

Road trip lovers and camping fanatics alike will love this vintage-inspired camper. Based on the iconic 1962 VW vehicle, LEGO’s camper gets every detail right, from the trademark safari windshield on the outside to the foldable furniture inside. Small details, like a “Make LEGO Models, Not War” LEGO T-shirt and a detailed engine add an authentic touch to the piece. Whether you’re into old car mechanics or simply want to take a trip back in time, this LEGO car will take you on a journey you won’t soon forget.

Buy it: Amazon

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Meet Your Home's Microbes in The Great Indoors

Taylor Wilcox/Unsplash
Taylor Wilcox/Unsplash

This year, you’ve probably been spending more time than you ever expected at home. You might be sharing space with family members, roommates, pets—and an entire universe of microbes. In The Great Indoors: The Surprising Science of How Buildings Shape Our Behavior, Health, and Happiness, science journalist Emily Anthes investigates homes, offices, schools, hospitals, and other places where we live, work, and play. She looks at how the design of our surroundings affects major aspects of our lives, even when we don’t realize it. In this excerpt, she explores the thriving communities of bacteria and fungi with which we share our abodes—and what they reveal about us.

In 2010, microbiologist Noah Fierer made his first foray into the indoor microbial world, cataloging the bacteria present in 12 public restrooms at the University of Colorado Boulder, where he teaches. (Among the findings: The floor and the toilet handles were home to similar kinds of bacteria, suggesting that some bathroom-goers were flushing the toilet with their feet—“a practice well known to germaphobes and those who have had the misfortune of using restrooms that are less than sanitary,” Fierer and his colleagues reported.) The following year, he studied the microbes in residential kitchens and partnered with Rob Dunn to launch the Wild Life of Our Homes project. They began with a small pilot study in North Carolina, recruiting 40 families to run cotton swabs across seven surfaces inside their homes: a countertop, a cutting board, a refrigerator shelf, a pillowcase, a toilet seat, a TV screen, and the trim around an interior doorway.

The homes were crawling with microbial squatters—more than two thousand types, on average. Different locations within the homes formed distinct habitats: kitchens harbored bacteria associated with food, while doorways were covered in species that typically live in leaves and soil. From a microbiological perspective, toilet seats and pillowcases looked strikingly similar; both were dominated by bacteria that typically live on our skin and in our mouths.

Beyond these commonalities, there was a lot of variation among the homes, each of which had its own microbial profile, sheltering a slightly different collection of organisms. But the researchers couldn’t explain why. So Fierer and Dunn launched a second study, asking more than one thousand families living across the United States to swab the dust that had collected on the trim around their interior doorways.

“We focused on that because nobody ever cleans it,” Fierer told me. “Or we don’t clean it very often—maybe you’re an exception.” (I am not.) Because the dust collects over months or years, the duo hoped it would give them the broadest possible look at indoor life, an inventory of the organisms that had floated, crawled, and skittered through the homes over the previous months and years. As Dunn put it: “Each bit of dust is a microhistory of your life.”

Back in the lab, the team analyzed the DNA fragments present in each dust sample, listing every organism that made an appearance. The numbers were staggering. In total, the indoor dust contained DNA from more than 116,000 species of bacteria and 63,000 species of fungi. “The shocker was the diversity of fungi,” Dunn told me. There are fewer than 25,000 species of named fungi in all of North America, which means that our houses could be teeming with organisms that are essentially unknown to science. In fact, when the researchers compared the indoor dust to samples that the volunteers had taken from the trim around an exterior door, they found that there was more microbial diversity inside the homes than outside of them.

Scientific American/Farrar, Straus and Giroux

Some of the species that Fierer and Dunn identified originate outside, hitching rides into our homes on our clothes or drifting in through open windows. (And they may not all be alive by the time they turn up inside; DNA sequencing can identify the organisms that are present in a sample, but it can’t distinguish between living creatures and dead ones.) Other kinds of bacteria actually grow in our homes—in our walls and our pipes, our air conditioning units, and our dishwashers. Some sprout on our houseplants or our food.

And a lot of indoor microbes, it turns out, are living on us. “We’re constantly shedding bacteria from every orifice and body part,” Fierer said. “It’s nothing to be grossed out about. It’s just the way it is.” Our individual microbiomes—the collection of microorganisms that live in and on our bodies—are unique, and we each leave our own microbial signatures on the places we inhabit. In one innovative study, re- searchers tracked three families as they moved into new homes; each family’s distinct blend of microbes colonized its new residence within hours. The scientists—led by Jack Gilbert, a microbial ecologist then at the University of Chicago—could even detect the individual microbial contributions of each family member. “People who spent more time in the kitchen, their microbiome dominated that space,” Gilbert explained. “People who spent more time in the bedroom, their microbiome dominated there. You could start to forensically identify their movement.”

Indeed, the bacteria that turn up inside a home depend enormously on who lives there. Fierer and Dunn found that Lactobacil­lus bacteria, which are a major component of the vaginal microbiome, were most abundant in homes in which women outnumbered men. When men were in the majority, different bacteria thrived: Roseburia, which normally live in the gut, and Corynebacterium and Derma­bacter, which both populate the skin. Corynebacterium is known to occupy the armpit and contribute to body odor. “Maybe it means that men’s houses smell more like armpits,” Dunn ventured. “Microbially, that’s a fair assessment.” The findings may be due to sex differences in skin biology; men tend to have more Corynebacterium on their skin— and to shed more skin microbes into the environment—than women do. (The researchers also acknowledge the possibility that a bachelor pad’s bacterial profile could be the result of “hygiene practices.”) In a subsequent study, Fierer and his colleagues showed that they could accurately predict the sex of the students living in a college dorm room simply by analyzing the bacteria in its dust.

Meanwhile, dogs introduce their own drool and fecal microbes into a home and track soil dwellers in from outside. (Dog owners never seem too bothered when Dunn tells them that Fido is smuggling an entire microbial zoo into their homes. “It’s a pretty fine conversation most of the time,” he told me. On the other hand, he noted, “If I say that every time your neighbor comes over, that he brings over a mix of beneficial microbes and pathogens, it just makes people scrub.”) Cats change a home’s microbial makeup more modestly, perhaps because they are smaller and venture outside less often. Using the dust DNA alone, Fierer and Dunn were able to predict whether a home contained a dog or a cat with roughly 80 to 90 percent accuracy.

While the bacteria in our homes mostly comes from us (and our pets), the fungi are another story. Fungi are much less abundant in our own microbiomes, and our houses are dominated by fungal species that originate outdoors. A home’s fungal signature, Fierer and Dunn found, was largely determined by where it was located. Houses in eastern states had different fungal communities than those in western ones. Ditto homes in humid climates compared with those in dry ones. The geographic correlation was so strong that Fierer and Dunn could use fungal DNA to determine, to within about 150 miles, where a house dust sample originated.

Fierer and Dunn did identify more than 700 kinds of fungi that were more common indoors than out, including a variety of household molds, yeasts, edible mushrooms, and fungi that live on human skin. Homes with basements had different fungi than those without them. And because some species of fungi feed on wood and other building materials, what our homes are made of affects the fungi that live there. “It’s kind of a ‘three pigs’ thing,” Dunn told me. “A stone house feeds different fungi from a wood house from a mud house. Because unlike the bacteria, they’re eating the house.”

 

Some of the microbes that inhabit our homes are known to cause disease. Black mold, which grows in and on our walls, can trigger allergies and respiratory problems. Aspergillus fumigatus, a fungus that can cause lung infections in people with weakened immune systems, lives in our pillows. Legionella pneumophila, a bacterium that causes Legionnaires’ disease, loves indoor plumbing. It nestles inside hot water tanks, cooling towers, and faucets, and spreads through airborne, or aerosolized, droplets of water. Streptococcus bacteria—which can cause strep throat, sinus and ear infections, pinkeye, meningitis, and pneumonia—are more abundant inside our homes than outside them, Fierer and Dunn found. Though the mere presence of these microbes isn’t necessarily dangerous, and not all strains cause illness, buildings can provide an infrastructure that helps diseases spread. Airborne influenza can waft through an office building’s ventilation system; a spray of Strepto­coccus can turn a doorknob into a booby trap.

But many indoor microbes are completely innocuous, and some may even have lifelong health benefits. In recent decades, the rates of asthma, allergies, and autoimmune diseases have skyrocketed in industrialized nations. Some scientists have theorized that the increasing prevalence of these diseases may be the fault of our modern lifestyles, which keep us at a distance from the robust microbial menageries that surrounded our ancestors for most of human evolution. As a result, our immune systems never get properly trained.

Evidence has been accumulating to support this theory. Studies show that children who live with dogs, which increase the richness and diversity of bacteria in a home, are less sensitive to allergens and less likely to develop asthma. (A dog might be the immune system’s best friend.) Children who grow up on farms, and are exposed to livestock and their microbes, appear to be similarly protected from allergies and asthma.

Some of the most compelling evidence comes from research on two American farming communities: the Amish and the Hutterites. Although the groups have much in common—including large families and Central European ancestry—just 5 percent of Amish kids have asthma, compared to 21 percent of Hutterite children. The communities also have distinct farming customs. The Amish, who generally eschew electricity, live on single-family farms and employ traditional agricultural methods, using horses to plow their fields. It’s not uncommon for Amish children to play in the family barns, which are typically located near their homes. The Hutterites, on the other hand, live together on big, industrial farms, complete with high-tech tools and equipment, and their children have less contact with livestock.

These differences may affect the children’s microbial exposures and the development of their immune systems. In 2016, scientists reported that house dust collected from Amish households had higher levels of endotoxins—molecules contained in the cellular membranes of some bacteria—than dust from Hutterite homes. What’s more, when they drew blood from kids in both communities, they found that compared to Hutterite children, Amish children had more neutrophils, white blood cells that help the body fight infection, and fewer eosinophils, which play a critical role in allergic reactions.

The researchers also whipped up some house-dust cocktails, mixing dust samples from Amish and Hutterite homes with water, and then shooting the slurries into the nasal passages of young mice. Then they exposed the mice to allergens. The mice that had received the Hutterite dust responded as expected; their airways trembled and twitched. But the mice that had received the Amish dust continued to breathe relatively freely, seemingly protected from this allergic response.

Although there’s still a lot to learn, the science suggests that a healthy home is one that’s full of uninvited guests. “We are exposed to microbes every day, and a lot of these are harmless or potentially beneficial,” Fierer told me. “We don’t want a sterile house.” Which is good, because it turns out that I don’t have one.