9 Facts About Human Decomposition

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From rotting corpses crawling with maggots to oozing bodies emitting stomach-churning stenches, the decaying human body is the stuff of nightmares, horror movies, and crime dramas. We're both fascinated and repelled by decomposition, which has given rise to many myths and urban legends. (No, hair and nails don't grow after death, and corpses never sit up on mortuary tables.) Here are nine fascinating facts that demystify how we transition from flesh to bone to dust.

1. DECOMPOSITION STARTS ALMOST IMMEDIATELY AFTER DEATH.

It takes approximately four minutes from the moment a person has breathed their last for the shortage of oxygen in their body to kick off a series of events happening at the microscopic level: The levels of carbon dioxide and acidity rise in the bloodstream, and toxic wastes build up, poisoning the cells. Then, enzymes within cells begin to eat away at them. Organs with high concentrations of enzymes and water, such as the liver and the brain, are ground zero for this process.

One of the first visible signs of death is when the eyes cloud over, a result of fluids and oxygen no longer flowing to the corneas. That can begin within 10 minutes [PDF] of death.

2. THERE ARE FIVE PHASES OF DECOMPOSITION.

The first phase is called fresh. It's characterized by cell autolysis, "or self-digestion": The cells burst open due to the work of enzymes, and fluids leak out. Fluid-filled blisters emerge on the skin, which slips easily off the body in large sheets.

Meanwhile, resident anaerobic bacteria in the gut begin to break down cells, beginning the second phase of decomposition: bloat. As these microbes work away, gases begin to accumulate in the intestines, and the surrounding tissues expand. The gases react with hemoglobin, a protein found in red blood cells, producing a green pigment in the veins ("marbling"), and the skin turns green, then black.

During active decomposition, the third phase, tissues begin to liquefy and decomposition fluids seep out through orifices. According to Dawnie Wolfe Steadman, director of the Forensic Anthropology Center at the University of Tennessee, Knoxville, the loss of tissue mass is the chiefly the work of fly maggots—which feast on tissues—and bacteria.

Advanced decomposition is when most soft tissues are gone, whatever skin is left has turned dry and leathery, and the skeleton is visible, thanks to the handiwork of yet more bugs. "While the fly maggots no longer have much to feed on, other insects such as beetles come," Steadman says. "They are capable of breaking down the tougher soft tissues, like tendons, ligaments, and even cartilage."

Skeletal decay is the end of the decomposition process. A variety of factors result in the breakdown or fragmentation of bones. Acidic soil, for example, dissolves an inorganic mineral compound called hydroxylapatite—a mix of calcium and phosphate—that accounts for 70 percent of our bone material [PDF]. Bones can also disintegrate when they are subjected to a variety of physical forces, including being gnawed on by scavengers or being slowly eroded by the flow of water.

How long each of the above stages lasts depends on factors such as temperature, burial conditions, and the presence of microbes, insects, and scavengers. Active decomposition in particular is greatly influenced by the temperature; flies lay their eggs in warmer months, so decomposition tends to be slower in colder temperatures. Bones generally begin to bleach within the first year, and algae and moss may grow on their surface. Large cracks tend to form after about a decade.

3. RIGOR MORTIS IS ONLY TEMPORARY.

Fans of shows like Law & Order: SVU are likely to be familiar with rigor mortis, or the stiffening of the body’s muscles following death. It begins within two to six hours, originating in the face and neck and spreading outwards toward the limbs. Rigor mortis is the result of the two types of fibers in our muscle cells—actin and myosin—becoming tightly linked by chemical bonds that develop in response to lower pH levels in the cells, creating inflexibility [PDF]. But this rigidity goes away within 1 to 3.5 days, as the bonds between the muscle fibers break and the muscles relax, once again starting with the face. As this happens, the body can release feces and urine.

Rigor mortis occurs more quickly and persists longer in cooler temperatures than in warmer ones; according to one study, rigor lasted for 10 days in corpses refrigerated at 39°F in a mortuary. What happens right before death can influence rigor mortis too: A high fever will shorten how long it lasts, while vigorous physical activity will cause it to set in sooner. These effects are likely caused by a drop in the levels of the chemical ATP (adenosine triphosphate), an energy driver in cells, and increased amounts of lactic acid, which lower the pH in muscle cells.

4. DECOMPOSITION DOESN'T SMELL AS BAD AS YOU'D EXPECT.

“People think bodies always smell awful,” says Melissa Connor, director of the Forensic Investigation Research Station at Colorado Mesa University. “But while there are a few times and phases [where the] remains are odiferous, for the most part, the smell is not overpowering.”

Malodorous gases build through the bloat phase, but the smells lessen as decomposition progresses. According to Connor, in the summer, a corpse can pass through the odiferous stages in 10 days or less.

A mix of gases is responsible for the “sickly sweet” stench of death. Of these, putrescine and cadaverine—produced when bacteria break down the amino acids ornithine and lysine, respectively—emit distinctive noxious odors. These gases can be absorbed through the skin and compete with or displace oxygen—a potential health risk for people working with decomposing bodies in closed environments, such as underneath a house or in a well shaft. A recent study suggests that putrescine may act as a warning signal that death is near, triggering a “flight-or-fight” response.

5. DECOMPOSITION CAN SOMETIMES CREATE "SOAPY" CORPSES.

Another stinky by-product of decomposition is a waxy substance called adipocere. It's formed from fat under wet conditions through a process called saponification (the same basic chemical reaction by which soaps are made from fats). Fresh adipocere smells like ammonia, but over time, adipocere dries out and the odor disappears. Philadelphia’s Mütter Museum has a specimen of a corpse encased in adipocere known as the Soap Lady, who was exhumed in 1875 from a city cemetery. The Smithsonian has a male counterpart: Soapman, who was also found in Philadelphia in 1875 during the construction of a train depot. He died around 1800.

6. THE 'NECROBIOME' COULD HELP US DETERMINE TIME OF DEATH MORE ACCURATELY.

Forensic entomologists use insects to infer time of death, but there are other potential biological clues. According to Steadman, forensic scientists are researching how different species of bacteria can influence decomposition, and if bacteria can help identify individuals.

"Some researchers are looking at the necrobiome—or all the little bacteria and fungi that inhabit a corpse—and seeing if changes in the necrobiome can inform time of death," Connor says. By knowing which strains of bacteria and other microbes are present at each phase of decomposition, scientists can put together a microbial clock to help estimate the time since death. Some of these microbes come from our own microbiome; others come from the surrounding soil, or are carried to the body by flies, other insects, and scavengers.

7. WITHOUT BUGS OR BACTERIA, DECOMPOSITION CAN SLOW WAY, WAY DOWN …

In December 1977, in Franklin, Tennessee, the Williamson County Sheriff was called to an antebellum estate called Two Rivers. The owners had reported a disturbance in the small graveyard attached to the estate. There, the sheriff’s department found a headless male corpse dressed in formal wear atop the broken coffin of a Confederate lieutenant colonel named William Shy, who had died in 1864. Forensic anthropologist William Bass was asked to examine the body.

In his book Death’s Acre, Bass writes that the corpse had been preserved in the early stages of decomposition; the "flesh was still pink," he notes. He estimated the man had been dead a year at most. But some things didn't add up, which puzzled Bass. The style of clothing was dated and the shoes were made of old materials. The corpse’s head was later found in the coffin, and the teeth had not seen modern dentistry. All of this led Bass to suspect that the body was in fact Shy’s.

Turns out he was right the second time around. Shy's corpse had been unceremoniously yanked out of his resting place by grave robbers. The 113-year-old body was so well-preserved because it was embalmed—which slows decomposition (by how much depends on the embalming process)—and because the cast-iron coffin was hermetically sealed, keeping out any insects and microbes that would have pushed decomposition beyond the early stages.

More recently, in May 2016, an airtight metal casket was unearthed in a backyard in San Francisco. The home had been built on the site of a cemetery. Inside the casket was the well-preserved body of a toddler, Edith Cook, who had died in 1876. News reports don’t explicitly state whether Edith was embalmed, but old ads from the casket’s manufacturers boast that it offered “perfect protection from water and vermin.”

Still, cast-iron coffins aren't decomposition-proof: In other cases, they've exploded due to bloat-stage gases. This gas buildup has been a problem for some modern "protective" or "sealer" caskets too.

8. … AND ENVIRONMENTAL CONDITIONS CAN ALTER DECOMPOSITION.

Certain environmental conditions are ideal for preserving bodies and creating natural mummies—which are unique because the skin survives active decomposition.

A combination of low oxygen, highly acidic water, and cool temperatures in European peat bogs turns corpses into bog bodies. While the acidic water breaks down bones, tannins in the peat and the lack of oxygen preserve skin—every expression, wrinkle, and fingerprint—with astonishing detail. Famous examples include the Tollund Man and Lindow Man.

La Doncella, or “The Maiden,” is an ancient Inca teenager who was left to die in the Andes Mountains in Argentina as a part of a ritual sacrifice. She was found in 1999, head down, appearing to be asleep. Though she died more than 500 years ago, her hair, skin, and clothing are all almost perfectly preserved. The high altitude, low temperatures, and low oxygen level account for La Doncella’s condition.

Another example of the preservative powers of the mountains is Ötzi, a natural mummy of a man who died about 5300 years ago. He was discovered in 1991 in Ötztal Valley Alps and has been preserved almost in his entirety. Though the glacier ice dehydrated his body, his skin, other tissues, organs and bones remain in great shape.

9. DISEASES THAT KILL THEIR HUMAN HOSTS CAN SURVIVE DECOMPOSITION.

A number of disease-causing viruses can hang around even after death. The Ebola virus is particularly contagious even after a person has died: It remains in their blood and other bodily fluids. Any contact with broken skin or the mucous membrane (which lines the nose, mouth, and other body cavities) of a healthy person is enough to pass on the infection. For this reason, the World Health Organization recommends that infected bodies be buried quickly and safely, with everyone handling the body wearing protective gear and the body buried in a coffin in the ground. The virus has been shown to persist in dead primates for up to a week.

Norovirus (the stomach flu) can also spread in a manner similar to Ebola, and it is possible to catch influenza from the infected mucus of a dead person. The smallpox virus remains in the scabs of a dead person for as long as a century—but at least it's not contagious from the dead to living.

15 Gripping Facts About Galileo

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Getty Images

Albert Einstein once said that the work of Galileo Galilei “marks the real beginning of physics.” And astronomy, too: Galileo was the first to aim a telescope at the night sky, and his discoveries changed our picture of the cosmos. Here are 15 things that you might not know about the father of modern science, who was born February 15, 1564.

1. There's a reason why Galileo Galilei's first name echoes his last name.

You may have noticed that Galileo Galilei’s given name is a virtual carbon-copy of his family name. In her book Galileo’s Daughter, Dava Sobel explains that in Galileo’s native Tuscany, it was customary to give the first-born son a Christian name based on the family name (in this case, Galilei). Over the years, the first name won out, and we’ve come to remember the scientist simply as “Galileo.”

2. Galileo Galilei probably never dropped anything off the leaning tower of Pisa. 

With its convenient “tilt,” the famous tower in Pisa, where Galileo spent the early part of his career, would have been the perfect place to test his theories of motion, and of falling bodies in particular. Did Galileo drop objects of different weights, to see which would strike the ground first? Unfortunately, we have only one written account of Galileo performing such an experiment, written many years later. Historians suspect that if Galileo taken part in such a grand spectacle, there would be more documentation. (However, physicist Steve Shore did perform the experiment at the tower in 2009; I videotaped it and put the results on YouTube.)

3. Galileo taught his students how to cast horoscopes.

It’s awkward to think of the father of modern science mucking about with astrology. But we should keep two things in mind: First, as historians remind us, it’s problematic to judge past events by today’s standards. We know that astrology is bunk, but in Galileo’s time, astrology was only just beginning to disentangle from astronomy. Besides, Galileo wasn’t rich: A professor who could teach astrological methods would be in greater demand than one who couldn’t.

4. Galileo didn't like being told what to do.

Maybe you already knew that, based on his eventual kerfuffle with the Roman Catholic Church. But even as a young professor at the University of Pisa, Galileo had a reputation for rocking the boat. The university’s rules demanded that he wear his formal robes at all times. He refused—he thought it was pretentious and considered the bulky gown a nuisance. So the university docked his pay.

5. Galileo Galilei didn't invent the telescope.

We’re not sure who did, although a Dutch spectacle-maker named Hans Lipperhey often gets the credit (he applied for a patent in the fall of 1608). Within a year, Galileo Galilei obtained one of these Dutch instruments and quickly improved the design. Soon, he had a telescope that could magnify 20 or even 30 times. As historian of science Owen Gingerich has put it, Galileo had managed “to turn a popular carnival toy into a scientific instrument.”

6. A king leaned on Galileo to name planets after him.

Galileo rose to fame in 1610 after discovering, among other things, that the planet Jupiter is accompanied by four little moons, never previously observed (and invisible without telescopic aid). Galileo dubbed them the “Medicean stars” after his patron, Cosimo II of the Medici family, who ruled over Tuscany. The news spread quickly; soon the king of France was asking Galileo if he might discover some more worlds and name them after him.

7. Galileo didn't have trouble with the church for the first two-thirds of his life.

In fact, the Vatican was keen on acquiring astronomical knowledge, because such data was vital for working out the dates of Easter and other holidays. In 1611, when Galileo visited Rome to show off his telescope to the Jesuit astronomers there, he was welcomed with open arms. The future Pope Urban VIII had one of Galileo’s essays read to him over dinner and even wrote a poem in praise of the scientist. It was only later, when a few disgruntled conservative professors began to speak out against Galileo, that things started to go downhill. It got even worse in 1616, when the Vatican officially denounced the heliocentric (sun-centered) system described by Copernicus, which all of Galileo’s observations seemed to support. And yet, the problem wasn’t Copernicanism. More vexing was the notion of a moving Earth, which seemed to contradict certain verses in the Bible.

8. Galileo probably could have earned a living as an artist.

We think of Galileo as a scientist, but his interests—and talents—straddled several disciplines. Galileo could draw and paint as well as many of his countrymen and was a master of perspective—a skill that no doubt helped him interpret the sights revealed by his telescope. His drawings of the Moon are particularly striking. As the art professor Samuel Edgerton has put it, Galileo’s work shows “the deft brushstrokes of a practiced watercolorist”; his images have “an attractive, soft, and luminescent quality.” Edgerton writes of Galileo’s “almost impressionistic technique” more than 250 years before Impressionism developed.

10. Galileo wrote about relativity long before Einstein.

He didn’t write about exactly the same sort of relativity that Einstein did. But Galileo understood very clearly that motion is relative—that is, that your perception of motion has to do with your own movement as well as that of the object you’re looking at. In fact, if you were locked inside a windowless cabin on a ship, you’d have no way of knowing if the ship was motionless, or moving at a steady speed. More than 250 years later, these ideas would be fodder for the mind of the young Einstein.

10. Galileo never married, but that doesn't mean he was alone.

Galileo was very close with a beautiful woman from Venice named Marina Gamba; together, they had two daughters and a son. And yet, they never married, nor even shared a home. Why not? As Dava Sobel notes, it was traditional for scholars in those days to remain single; perceived class difference may also have played a role.

11. You can listen to music composed by Galileo's dad.

Galileo’s father, Vincenzo, was a professional musician and music teacher. Several of his compositions have survived, and you can find modern recordings of them on CD (like this one). The young Galileo learned to play the lute by his father’s side; in time he became an accomplished musician in his own right. His music sense may have aided in his scientific work. With no precision clocks, Galileo was still able to time rolling and falling objects to within mere fractions of a second.

12. His discoveries may have influenced a scene in one of Shakespeare's late plays.

An amusing point of trivia is that Galileo and Shakespeare were born in the same year (1564). By the time Galileo aimed his telescope at the night sky, however, the English playwright was nearing the end of his career. But he wasn’t quite ready to put down the quill: His late play Cymbeline contains what may be an allusion to one of Galileo’s greatest discoveries—the four moons circling Jupiter. In the play’s final act, the god Jupiter descends from the heavens, and four ghosts dance around him in a circle. It could be a coincidence—or, as I suggest in my book The Science of Shakespeare, it could hint at the Bard's awareness of one of the great scientific discoveries of the time.

13. Galileo had some big-name visitors while under house arrest.

Charged with “vehement suspicion of heresy,” Galileo spent the final eight years of his life under house arrest in his villa outside of Florence. But he was able to keep writing and, apparently, to receive visitors, among them two famous Englishmen: the poet John Milton and the philosopher Thomas Hobbes.

14. Galileo's bones have not rested in peace.

When Galileo died in 1642, the Vatican refused to allow his remains to be buried alongside family members in Florence’s Santa Croce Basilica; instead, his bones were relegated to a side chapel. A century later, however, his reputation had improved, and his remains (minus a few fingers) were transferred to their present location, beneath a grand tomb in the basilica’s main chapel. Michelangelo is nearby.

15. Galileo might not have been thrilled with the Vatican's 1992 "apology."

In 1992, under Pope John Paul II, the Vatican issued an official statement admitting that it was wrong to have persecuted Galileo. But the statement seemed to place most of the blame on the clerks and theological advisers who worked on Galileo’s case—and not on Pope Urban VIII, who presided over the trial. Nor was the charge of heresy overturned.

Additional sources: The Discoveries and Opinions of Galileo; Galileo's Daughter; The Cambridge Companion to Galileo.

10 Things You Should Know About Asthma

iStock.com/Wojciech Kozielczyk
iStock.com/Wojciech Kozielczyk

To anyone with asthma, the feeling of an attack is unmistakable. Patients have compared an asthma attack's feeling of breathlessness, caused by inflammation in the lungs and airways, to being smothered by a pillow or having an elephant sit on their chest. Medical experts have already figured out some aspects of asthma, like how to diagnose and treat it, but other components, like what causes asthma and how to cure it, remain unclear. From the triggers people encounter at work to the connection to allergies, here are some facts about asthma symptoms and treatments you should know.

1. Asthma attacks are related to allergies.

The physical process that occurs when someone has a sneezing fit during pollen season is similar to what happens during an asthma attack. But while the former causes discomfort, the latter produces potentially life-threatening symptoms. When people with allergies are exposed to an allergen like pollen, they produce antibodies that bind to that allergen. This signals the body to release the chemicals that cause allergic symptoms. In most people, the symptoms are limited to the head, such as a runny nose or watery eyes, but in people with asthma, they're felt in the lungs. If the lungs are inflamed, the airways that carry air swell up and fill with mucus, constricting airflow and causing common asthma symptoms like coughing, wheezing, and shortness of breath. Such asthma attacks can be fatal when patients can’t get enough air to their lungs.

2. Asthma is the most prevalent chronic disease among children.

Asthma is common, affecting 25 million in the U.S. alone, and of those patients, about 7 million are children. Most people with the disease develop it during childhood. Asthma is the most prevalent chronic illness among kids, and each year, students miss 13.8 million school days because of it.

3. Asthma may be inherited.

Doctors aren’t entirely sure what causes asthma, but they know it sometimes runs in families. A 2010 study found that people with one parent with the condition were nearly twice as likely to have it themselves, and people with a parent and a grandparent with asthma were four times more likely to develop it. Because asthma is connected to allergies, a genetic disposition toward allergies, known as atopy, may explain some inherited asthma cases.

4. Asthma is surprisingly easy to diagnose.

One of the simplest ways to diagnose asthma is through a lung function test. If a patient is reporting asthma symptoms (coughing, chest tightness, a feeling of not getting enough air), their doctor may check the strength of their exhalations before and after having them use an inhaler. If their breathing improves with the medicine, they likely have asthma. An X-ray of the patient’s chest can also be used to reach an asthma diagnosis.

5. Kids who grow up around germs are less likely to have asthma.

A person’s environment early in life may also play a role in whether or not they develop asthma. People who grew up in rural areas, around animals, and in large families are less likely to have asthma than those who did not. One possible explanation is the hygiene hypothesis: According to this theory, kids who were exposed to germs and pathogens while their immune systems were developing are better equipped to deal with allergens, while kids who were sheltered from germs may be more likely to have an exaggerated (and in the case of asthma, potentially deadly) immune response to harmless substances. The hygiene hypothesis hasn’t been proven, however, and it’s definitely not an excuse to expose children to infections in an attempt to strengthen them against asthma attacks in the future.

6. Asthma triggers are everywhere.

To manage their symptoms, doctors tell asthma patients to limit exposure to their triggers when possible. Common asthma triggers include irritants and allergens like dust, tobacco smoke, car exhaust, mold, pet dander, and smoke from burning wood. Triggers that don’t come from the environment, like colds, sinus infections, acid reflux, and hyperventilation brought on by stress, can be even harder to avoid.

7. There's one asthma trigger patients shouldn't avoid.

Physical activity causes fast breathing, which can provoke asthma attacks in some people with the condition. There’s even a type of asthma called exercise-induced bronchoconstriction that specifically describes people who suffer from these kinds of attacks. But the risks of living a sedentary lifestyle outweigh those of exercising carefully, even with asthma. Instead of cutting out cardio altogether, doctors work with patients to come up with an exercise plan that’s safe for them. This might include warming up and using an inhaler before working out, practicing cool-down activities afterward, and wearing scarves or masks to limit exposure to irritants that may also trigger asthma symptoms.

8. There are two types of asthma treatments.

Long-term controllers and quick-relievers are the two types of medications used to treat asthma. Immediate medicines like short-acting beta agonists and anticholinergics relax muscles in the airways when flare-ups occur, and they’re typically administered directly to the lungs with an inhaler. Long-term medications help keep asthma symptoms under control over time are taken as often as once a day, regardless of whether symptoms are present. They include inhaled long-acting beta agonists and corticosteroids, biologic injections, and theophylline and leukotriene modifier pills and liquids. All of these medications suppress asthma symptoms by either relaxing muscles, reducing swelling, or preventing inflammation in the airways.

9. Asthma can be an occupational hazard.

Occupational asthma develops when a patient’s triggers come from their work environment. According to the National Institutes of Health, wood dust, grain dust, animal dander, fungi, and various chemicals are some of the most common asthma triggers that patients encounter in the workplace. Bakers, farmers, laboratory workers, millers, and woodworkers predisposed to asthma are all at higher risk.

10. There's no cure for asthma, but symptoms can lessen over time.

Though asthma is treatable, there’s no cure for the chronic illness. Some people, however, do appear to grow out of the condition after suffering from it as kids. It’s possible for asthma symptoms to become less severe and go into remission as patients get older, but once someone is diagnosed with asthma, the risk of an episode never goes away completely. Changes in hormone levels are a factor that could possibly bring asthma symptoms back in patients who haven’t experienced an attack in years.

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