What happens to the human body when it is burned and how does burning affect the bone? Professor Tim Thompson discusses his recent research.
Fire is a very destructive force, capable of great damage. Burned human remains can be found in a range of situations, from archaeological funerary urns, to aeroplane crashes, to volcanic eruptions, to modern cremations. Despite this range of contexts, the actual impact on the body and bone (which we term ‘heat-induced changes’) are the same. In fact, in many ways the changes we see due to fire are the same as normal diagenesis over time – just a lot quicker. It is important to note that the skeleton does not ‘turn to ash’ upon burning. Even within modern crematoria, which burn efficiently and at high temperatures, the skeleton will survive. The skeletal remains are then raked from the cremator and the remains placed in a machine known as a cremulator, which grinds the bones into ash. This is because people don’t want to scatter recognisably human fragments of their loved ones.
Bodies during burning
The human body is made up of soft and hard tissues, and fire will have a dramatic effect on both. Fire can be fatal in different ways, but the most common are either due to the heat or suffocation from the smoke produced. The smoke can restrict oxygen flow into the body and contain poisons which can be lethal. The heat of the fire will cause significant damage to the body.
The fire will cause the soft tissues to contract, which causes the skin to tear and the fat and muscles to shrink. The internal organs will also shrink. The muscles contract due to burning and this causes the joints to flex. As a result, burned bodies are often contorted into what’s known as a pugilistic, or boxer pose. This is most clearly seen in the flexed bodies recovered from the ancient city of Pompeii (AD 79) when many died from the extreme heat of the pyroclastic flow from the volcano Vesuvius.
The heat will also cause significant changes to the bone. The skeleton does not burn in a uniform way. Some bones will burn at a higher intensity than others due to factors such as body fat distribution, proximity to the heat source, etc. For example, the humeri below are from the same individual, but the darker one on the left was burned at a lower intensity to the one on the right, which has become completely calcined.
Humeri (arm bones) from a single individual. Note the differences in colour (copyright Joy Szigeti)
Quite often the peripheral bones of the hands and feet will not be burned to such a high intensity as those at the centre of the body, where most fat is located. Body fat acts as a source of fuel and people with more fat will burn at a higher intensity than very thin people.
Bone goes through four stages of transformation when burned.
Removal of water from the bone due to moisture evaporating in response to the heat. This occurs at a temperature range of °C 100-500.
An unburned fragment of animal bone on the left and a partially dehydrated fragment of animal bone which has been burned at a low temperature on the right
The organic component of the bone (the collagen) is lost.
Fragments of animal bone that have been dehydrated due to burning on the left and fragments that have decomposed due to higher intensity burning on the right
Changes to the inorganic, mineral part of the bone, the carbonates. This occurs at a temperature range of °C 500-1100.
Decomposed fragments on animal bone on the left and fragments showing inversion on the right due to higher intensity burning
The crystals that form the bone mineral start to melt and coalesce together. This occurs at a temperature range of °C 700-1200
The fragments on the right show evidence of fusions due to higher intensity burning
These four stages are not discrete phases – a given bone could be experiencing all four stages in different parts at the same time.
What do these changes mean?
These stages result in a number of alterations to the bone structure and appearance. These can make it more difficult for anthropologists who are trying to use these burned remains to produce an osteoprofile.
The Dehydration and Decomposition stages cause an increase in porosity (small holes) in the bone, which leads to increased fracturing, fragmentation and breakage. This is why burned remains are often very fragmented.
The loss of the organic material also causes significant colour change. For many decades, anthropologists and archaeologists have tried to use colour change in burned bone as a way of predicting the temperature reached during burning. They then use this information to make inferences regarding the burning event. As bone burns, its colour moves from a natural creamy-brown state to dark grey to black to light grey and then pure white. The problem with using colour in this way is that it is not only temperature that influences colour change, but also the duration of burning, the oxygen levels, the amount of soft tissue and so on.
The Inversion and Fusion stages result in a reorganisation of the mineral structure of the bone, which leads to shrinkage, reduced porosity, increased crystallinity and a conversion to a more ceramic-like material. In fact, when bone is very well burned it becomes calcined and it can then feel and sound a bit like ceramic. So bone burned at a high intensity can actually preserve much better in the ground than bone burned at a low intensity because of this change to a more ceramic-type crystal structure.
Below are a series of images of bone burned at differing intensities when viewed under a scanning electron microscope. You can see that at low intensity, the bone has holes and fractures in the surface and these get larger under medium intensity burning. These features will mean that the bone is more fragile and may not survive so well in the ground. Then under higher intensity burning, holes become smaller and the cracks disappear. This is the point at which the bone becomes a bit like ceramic and it will then preserve better in the ground.
Fractures Characteristic of Burning
When fresh bone is burned (i.e. a fleshed body) characteristic u-shaped fracturing will be visible. These u-shaped fractures can still occur some time after death, but once the soft tissues have decomposed the bone no longer fractures in this way.
U-shaped fractures on a long bone (Copyright Joy Szigeti)
If the body is burned after soft tissue decomposition a grid-like fracture pattern is produced (see below).
*Grid-like fracture patterns on a Neolithic bone from Guernsey (Cataroche and Gowland 2015).
Sometimes a body is burned after it has fully decomposed. This could be for a number of reasons, such as the building where the body is located catching fire, or because perpetrators are trying to confuse the forensic investigation. In these cases, it is possible to say if significant decomposition had occurred before burning by examining the subtle changes to bone surface and microstructure that the fire causes.
An approximate age-at-death and sex can still be determined from cremated human remains. Pathological evidence can also be observed in burned remains, including joint disease, or cut marks. This is useful for forensic contexts because perpetrators often think that burning a body will eliminate evidence of trauma (such as knife wounds or dismemberment), but this is not always the case.
DNA can survive in the bone but it is often degraded. Stable isotope evidence for strontium can also be retrieved from the burned remains and experiments are ongoing at Durham University regarding the temperature at which collagen for carbon and nitrogen analysis will still survive. Further examples of recent experiments to advance forensic investigations of burned human remains are presented in the next step.
© Tim Thompson and Rebecca Gowland
The heat of the fire will cause significant damage to the body. The fire will cause the soft tissues to contract, which causes the skin to tear and the fat and muscles to shrink. The internal organs will also shrink. The muscles contract due to burning and this causes the joints to flex.What is the hardest thing to burn on a human body? ›
The body parts that do not burn are bone fragments. Teeth usually burn during cremation, but not entirely. Teeth are made up of four different kinds of tissue—the soft tissue (pulp) is burned during cremation, while the toughest tissue (enamel) may survive the cremation.How does the body react to burns? ›
First-degree burns affect only the outer layer of the skin. They cause pain, redness, and swelling. Second-degree burns affect both the outer and underlying layer of skin. They cause pain, redness, swelling, and blistering.How hard is it to burn a human body? ›
Surely the fire would be doused rather quickly even if the body did manage to catch fire. That's why it takes flames of around 1600 degrees Fahrenheit over two hours or more to cremate human remains.How flammable are human bodies? ›
Humans are not very flammable
With very few exceptions, people just don't burn. We call heat-related injuries burns, but our bodies are not particularly good at sustaining a fire. If you were to hold your hand over a candle, your hand would not burst into flame, but you would be injured by the heat.
Do teeth burn during cremation? Teeth usually burn up during the cremation process. Tooth fragments that are not burnt up will be ground during the ash processing.Which organ does not burn? ›
The bones of the body do not burn in fire. Why do the bones not burn in fire? For the burning of bone, a very high temperature of 1292 degrees Fahrenheit is required. At this temperature also, the calcium phosphate from which the bones are made will not entirely turn into ash.What organs are affected by burns? ›
The lungs, heart, brain, and kidneys are particularly susceptible. Infection is also a major concern. Burns damage the skin's protective barrier, meaning bacteria and other foreign invaders can sneak in. Burns also weaken the immune system, so the body is less able to fight off threats.Do burns feel hot to the touch? ›
It can be hard to tell if a minor burn is infected because the skin surrounding a burn is usually red and may become warm to the touch, both of which are also signs of infection. Any change in the appearance of a burn, or in the way that the person feels, should be brought to the attention of a doctor.At what point does human skin burn? ›
At 118 degrees, human skin can sustain first-degree burns; a second-degree burn injury can occur at a temperature of 131 degrees. Human skin is destroyed when temperatures reach 162 degrees.
Cremation reduces the body to cremated remains in a matter of hours, while traditional burial follows a slow and natural decomposition process. Direct cremations are more cost effective than direct burials, as they do not require embalming.How many hours does it take to burn a human body? ›
The cremation process for humans takes between 1.5 and 2 hours. The body is placed in a retort, which is then heated to between 1400 and 1800 degrees Fahrenheit. At this temperature, the body burns, and the bones turn to ash. After the body has been cremated, the ashes are placed in an urn and returned to the family.What does a burning body smell like? ›
Emergency workers and survivors of war atrocities say charred flesh simply smells like nothing else. The scent is nauseating and sweet, putrid and steaky, or something like leather being tanned over a flame. The smell can be so thick and rich that it's almost a taste.How long will a body burn? ›
The actual cremation (burning of the dead body, turning them into ashes) can take about 3-4 hours, and processing the cremated remains takes another 2-3 hours.How much of your body can you burn and survive? ›
Most people can survive a second-degree burn affecting 70 percent of their body area, but few can survive a third-degree burn affecting 50 percent. If the area is down to 20 percent, most people can be saved, though elderly people and infants may fail to survive a 15 percent skin loss.What does fire do to humans? ›
Fine particles are able to travel deeply into the respiratory tract, reaching the lungs. Inhaling fine particles can cause a variety of health effects, including respiratory irritation and shortness of breath, and can worsen medical conditions such as asthma and heart disease.Why is the skull broken during cremation? ›
This is done to ensure that the head of the deceased person burns well. So, when the head gets burnt, it is broken with a stick. Let us tell you that this process in the crematorium is termed the Kapaal Kriya.What does the Bible say about cremation? ›
What does the Bible say about cremation? According to most Biblical study websites, there is no explicit scriptural command for or against cremation. There are no passages that forbid cremation, according to most Biblical scholars.Do bodies scream during cremation? ›
We think this is an urban legend. We've witnessed many cremations and never heard a scream. But then again, cremation retorts aren't silent either. Now, bodies do make all kinds of gnarly noises.Which organ never stops? ›
Your Nose and Ears Are the Only Body Parts That Don't Stop Growing | The Healthy.
The brain itself does not feel pain because there are no nociceptors located in brain tissue itself. This feature explains why neurosurgeons can operate on brain tissue without causing a patient discomfort, and, in some cases, can even perform surgery while the patient is awake.What part of the human body feels the least pain? ›
Similarly with cold receptors: once the chill drops to frost-bite level, a set of pain receptors takes command. These produce a slow, burning pain; the faster the neurons fire, the more intense the pain. The tongue, lips, and fingertips are the most touch- sensitive parts of the body, the trunk the least.What is the rule of nines? ›
The size of a burn can be quickly estimated by using the "rule of nines." This method divides the body's surface area into percentages. The front and back of the head and neck equal 9% of the body's surface area. The front and back of each arm and hand equal 9% of the body's surface area.What are the 2 biggest concerns with a patient who has severe burns over the body? ›
Complications of deep or widespread burns can include: Bacterial infection, which may lead to a bloodstream infection (sepsis) Fluid loss, including low blood volume (hypovolemia)What burn causes the most pain? ›
Superficial dermal burns are initially the most painful. Even the slightest change in the air currents moving past the exposed superficial dermis causes a patient to experience excruciating pain. Without the protective covering of the epidermis, nerve endings are sensitized and exposed to stimulation.What is a burn that won't heal? ›
A skin wound that doesn't heal, heals slowly or heals but tends to recur is known as a chronic wound. Some of the many causes of chronic (ongoing) skin wounds can include trauma, burns, skin cancers, infection or underlying medical conditions such as diabetes. Wounds that take a long time to heal need special care.What happens if you put ice on burn? ›
Should I use ice to cool the burn? No, ice could damage the skin. Use cold water to cool the burn. If you don't have access to cold running water, pour other cold liquids such as milk, soft drinks or beer over the burn to cool it.How bad is a burn if it turns white? ›
Full-thickness burns (also called third-degree burns) cause damage to all layers of the skin. The burned skin looks white or charred. These burns may cause little or no pain if nerves are damaged.Can you survive 95% burns? ›
In one retrospective review of 238 severely burned patients, the survival rate for patients with >95 percent total body surface area (TBSA) burns was approximately 50 percent for children aged 14 years and younger, 75 percent in adults 45 to 64 years, and 30 percent in older patients .Can you survive 90% burns? ›
A few decades ago, burns covering half the body were often fatal. Now, thanks to research—a large portion of it supported by the National Institute of General Medical Sciences (NIGMS)—people with burns covering 90 percent of their bodies can survive, although they often have permanent impairments and scars.
According to most dermatologists, the ideal shower temperature is anywhere between 98°F (37°C) and 104°F (40°C)—and no more than 105 °F (41°C).What kills you first in a fire? ›
Smoke and toxic gases kill more people than flames do. Fire produces poisonous gases that make you disoriented and drowsy. Asphyxiation is the leading cause of fire deaths, exceeding burns by a three-to-one ratio.Is cremation a sin according to the Bible? ›
A: In the Bible, cremation is not labeled a sinful practice. Frankly, the topic is not dealt with at all in terms of the detailed lists of instructions for living and dying set forth by almighty God in the Old and New testaments. The short answer to your question appears to be no, cremation is not a sin.Why can't Catholic be cremated? ›
For centuries, religious authorities believed that cremation prevented resurrection of the body and forbade Catholic families from cremating their loved ones. Over time, the Church has amended its stance on cremation, lifting its ban and issuing guidelines for how to handle ashes with care.Do they drain the blood before cremation? ›
FAQ Cremation Preparation
Is a body drained before cremation? Draining a body of fluids does not happen before cremation. If a body is embalmed before cremation, the bodily fluids are exchanged (drained, and then replaced) with chemicals during the embalming process.
Between carbs and protein, carbs get burned first and supply your body with short- and long-term energy.What happens to a body if there is no funeral? ›
You don't necessarily need to worry about what happens to your body if you can't afford a funeral. Signing a form at the county coroner can authorize the release of your body to the state or county for burial or cremation. It may be possible to pay a fee to recover your ashes if your family would like them.What does human meat smell like when cooking? ›
Seabrook noted that, in raw form, human meat looks like beef, but slightly less red, with pale yellow fat. When roasted, the meat turned grayish, as would lamb or veal, and smelled like cooked beef.Why does my insides smell bad? ›
A fishy or foul stench that won't go away could be a sign of infection or another condition -- especially if it comes with itching, burning, or discharge. Bacterial vaginosis, caused by too much normal bacteria, is the most common reason. The sexually transmitted infection (STI) trichomoniasis also causes odor.What does blood smell like? ›
An empirical test of the reaction of blood on the skin by Glindemann and colleagues  showed that a distinctive 'metallic' smell was produced, which was attributable to the oxidization of the hemoglobin's iron molecules in the reaction with fat lipids in the skin.
How long does a cremation process take? Cremations last between one and three hours with cooling taking a further one or two hours. This depends on cremation temperatures, the size of the deceased, and coffin material.Do belly buttons burn during cremation? ›
Something that people don't often know is that the belly button never burns to ash; it remains hard and in the same shape.How long does it take for a body to fully decompose? ›
If insects can be excluded, a body will decompose quite slowly, because maggots are the most voracious flesh feeders. Although an exposed human body in optimum conditions can be reduced to bone in 10 days, a body that is buried 1.2 m under the ground retains most of its tissue for a year.What is the most common cause of death in burn patients? ›
The majority of burn injury death cases result from arising complications, not the burn injury itself. Shock is a common cause of burn injury death. Burn injury death from shock typically occurs within a week of the incident.What is the rule of 5 in burns? ›
For obese patients weighing more than 80 kg a rule of fives is proposed: 5% body surface area for each arm, 5 x 4 or 20% for each leg, 10 x 5 or 50% for the trunk, and 2% for the head.What did humans eat before fire? ›
Before that climate shift, our distant human ancestors—collectively known as hominins—were subsisting mostly on fruits, leaves, seeds, flowers, bark and tubers. As the temperature rose, the lush forests shrank and great grasslands thrived.Why do humans like fire so much? ›
Humans have long been drawn to fire; our ancient ancestors used it for warmth, protection and cooking. In fact, fire was critical for our evolution. But thousands of years later, with all our modern electric lighting and cooking facilities, fire has become a comfort rather than a necessity in the developed world.How does fire cause death? ›
In addition to producing smoke, fire can incapacitate or kill by reducing oxygen levels, either by consuming the oxygen, or by displacing it with other gases. Heat is also a respiratory hazard, as superheated gases burn the respiratory tract. When the air is hot enough, one breath can kill.What is a burn that doesn't hurt? ›
These burns involve all layers of the skin and are usually dry or leathery to the touch. They can appear ashen or charred black or brown. If the burn has damaged nerve endings, the patient may have no sensation of pain.
Nylon, polyester and acrylic tend to be slow to ignite but once ignited, severe melting and dripping occurs. Wool is comparatively flame-retardant. If ignited, it usually has a low burning rate and may self-extinguish. Glass fibers and modacrylic are almost flame-resistant.
Superficial dermal burns are initially the most painful. Even the slightest change in the air currents moving past the exposed superficial dermis causes a patient to experience excruciating pain.What part of the body burns the most? ›
The largest muscles (and therefore the largest calorie burners) are in the thighs, abdomen, chest, and arms.What is the weakest burn? ›
First-degree (superficial) burns
First-degree burns affect only the epidermis, or outer layer of skin. The burn site is red, painful, dry, and with no blisters. Mild sunburn is an example. Long-term tissue damage is rare and usually consists of an increase or decrease in the skin color.
These burns destroy all layers of your skin, as well as your bones, muscles, and tendons.
Burns—even minor ones—can be very painful. A minor burn may heal within several days, while a more serious burn may take weeks or even months to heal completely. You may notice that the burned area feels tight and hard while it is healing.Which metal Cannot burn? ›
Iron has a strong molecular force of attraction. Hence when heated it doesn't reach its ignition temperature and doesn't burn.Why does water stop fire? ›
Water cools and smothers the fire at the same time. It cools it so much that it can't burn anymore, and it smothers it so that it can't make any more of the oxygen in the air explode. You can also put out a fire by smothering it with dirt, sand, or any other covering that cuts the fire off from its oxygen source.What things Cannot be burned? ›
- Mineral wool.
- Gypsum boards.
- Asbestos cement.
- Perlite boards.
- Calcium silicate.
- Sodium silicate.
So Regan goes on to say that it's widely accepted that breaking your femur is the most horrific, painful injury there is.What is the rule of 9? ›
The size of a burn can be quickly estimated by using the "rule of nines." This method divides the body's surface area into percentages. The front and back of the head and neck equal 9% of the body's surface area. The front and back of each arm and hand equal 9% of the body's surface area.
soreness in the burned area, which usually lasts for 2–3 days.What burns first on a human body? ›
The body burns sugars first. Low glycogen levels (stored carbohydrates) combined with high-intensity exercise creates opportunities for the body to burn higher amounts of muscle—not what anyone wants.What does your body burn off first? ›
Your muscles first burn through stored glycogen for energy. “After about 30 to 60 minutes of aerobic exercise, your body starts burning mainly fat,” he explains. (If you're exercising moderately, this takes about an hour.) Experts recommend at least 30 minutes of cardio two to three times a week.