Do all humans experience flatus regardless of their diet?

Do all humans experience flatus regardless of their diet?

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Flatus frequency is affected by diet, so I was wondering if flatus production solely depends on the food eaten, meaning that some people never ever release flatus because they don't eat any flatus-producing food. I guess if they say they don't, they're probably in denial…

Eventhough food contributes the most to flatulance, it can also be caused by swallowing air when you chew gum or smoke. It can also be caused by health conditions like coeliac disease and gastroenteritis (reference). So it is indeed hard to believe when people claim that they never fart.

Flatus is a normal product of digestion. To some extent flatus production does not depend on the types of food eaten as some of the gas is nitrogen just from air swallowed while eating. Some of the gas produced may be from bacteria in the intestinal tract. Depending on the species they may not be particularly finicky eaters, and may produce gas from any biodegradable food-item.

Causes of excessive gas and flatulence in elderly

Passing gas is a normal body reaction, but some people can experience excessive gas and flatulence as they age. While most excess gas and flatulence can be easily dealt with, there are situations where it can be a sign of an underlying health issue.

We all know that excessive gas or flatulence is not a medical emergency. Most of the gas we pass is due to the breakdown of foods in our bodies. Food consumption leads to hydrogen, carbon dioxide, and methane generation. Meanwhile, the odor is from other waste gases, including skatole and sulfur-containing substances. Excessive gas becomes a concern if a person develops other unusual symptoms along with the gas, such as cramping, diarrhea, constipation, bloody stools, or nausea and vomiting. These could be the sign of an inflammatory bowel disease, an intestinal bacterial overgrowth, an infection, or irritable bowel syndrome.

Farts May Get Worse With Age, Doctors Warn

Old folks tend to have the worst farts, according to Dr. Sarina Pasricha, a gastroenterologist. And there’s a method to their flatulence. As we age, our GI systems tend to slow down and become more prone to constipation the medications and decreased physical activity slow digestion down further. The result of all that backed-up energy is doubly offensive gas — explaining why Grandpa’s farts ruin family functions.

“The longer poop stays in the colon, the more the gut bacteria ferment, resulting in gas,” Pasricha told Fatherly. But she clarifies that the epidemiological phenomenon of gnarly elder farts is mere conjecture. “There have been no studies to date that clearly show an increase in flatulence as people age,” she says.

The only research that attempted to rate how fart potency changes over time analyzed data from 16,537 participants as part of the National GI Survey. Participants reported bloating, gas, constipation, diarrhea, abdominal pain, and other Thanksgiving-ruining symptoms on a mobile app. Results revealed that, although increased age was correlated with increased GI ailments, there was no increase in flatulence. If anything, the survey results suggested that fart frequency declines with age.

But Pasricha has her doubts. The sample included only 296 people over the age of 65, and more dignified older folk were free to lie about their flatulence. And then there’s the biology itself. “As people age, their anal sphincter muscles weaken and they are less able to hold in their gas,” Pasricha says. Anatomically speaking, we would expect greater fart frequency and less ability to wait for an opportune moment.

Whether old people farts are a societal problem or not, there are ways to mitigate the situation. A low FODMAP diet or an elimination diet that is low in fermentable sugars and polyols should take the edge off, Pasricha says. Then there’s always over the counter medications that help reduce gas, and it’s important to consult with a doctor if symptoms of gassiness and bloating persist. They may be able to adjust some medications or tailor more specific medical recommendations on a case-by-case basis.

And it’s always possible the survey was correct. Perhaps old people farts aren’t really a problem. “We found that reported flatus events per day decreases as individuals age, even after adjusting for covariates,” the study authors write. “The term ‘old fart’ may be inaccurate. ‘Young fart’ seems more apt.”

10 Fascinating Facts About Flatus

Flatulence makes us laugh -- and cry, depending on our proximity to the smelly performance. We love surprise whoopee cushions and blowing raspberries, and because of "Despicable Me 2" the Fart Blaster was one of the hottest toys of 2013. There's even a man on YouTube who has clocked his own fart at more than three minutes long I repeat, three minutes long. That rivals 19th-century entertainer Joseph Pugol, who could (and would) toot gassy tunes from center stage at his Moulin Rouge audience.

You might want a front row seat to the show, because that foul flatulence actually contains a compound that might be good for you, as a way to possibly treat health problems including arthritis, diabetes, heart failure and stroke by preventing mitochondrial damage [source: University of Exeter]. And you thought the smell was only there for embarrassment. Read on for 10 more facts about your flatus (gas), including who's really to blame for your farts.

10: Intestinal Bacteria Are Actually the Ones Doing the Farting

You have 37.2 trillion cells in your body and if you think that sounds like a lot, your body also is home to more than 10 times that amount of one-celled microbes (bacteria and yeast). A large percentage of those live in your digestive tract [source: Strippoli, LiveScience]. Clostridium, E. coli, Klebsiella these microorganisms, for example, among others, are part of the intestinal flora living in your colon. And there they hang out, dining on the undigested food that ends up in the lower intestines. The gases that make up flatulence are the byproduct -- the waste product -- these microbes produce as they break down those carbohydrates in your colon. Go ahead and blame your farts on them.

9: Most of Any Fart Is Odorless

Only 1 percent of what makes up a fart is responsible for that fart's odor. As much as 99 percent of a fart is carbon dioxide, hydrogen, nitrogen, oxygen and methane. The exact makeup of your farts is personal, like a fingerprint -- the biology of a gut differs from person to person. But it's actually the small remainder of intestinal gas -- sulfurous gases -- that can really stink up a room. Hydrogen sulfide, for example, gives farts a sulfury, rotten egg odor, while flatulence that smells like rotting cabbage is likely caused by a build-up of methanethiol. Sweet-smelling farts? That's dimethyl sulfide to blame. [source: Kluger]. Diet matters when it comes to how stinky our farts are, and it's not just sulfur-containing foods such as cabbage and kale (although they don't help) -- a diet full of complex carbohydrates (fiber, sugar and starches) is a diet full of flatus.

8: Holding Gas in Isn't Really Bad for You

You can't hold your gas in forever it's going to come out whether you're ready for it or not. Perhaps as a belch or perhaps as a fart, but regardless of form, it will escape. And sometimes in close proximity to (gasp) other people. Should you go ahead and hold it in, or is it healthier to always let it out and blame the dog? It's unlikely holding your flatus in will hurt you although, it will likely cause you some physical pain, bloating, abdominal discomfort (including dyspepsia) and heartburn (pyrosis).

7: About 14 Farts a Day Is Normal

You probably fart more during a 24-hour period than you think you do. Even if you're holding in a fart from time to time as you go through your day, you can't consciously deny your gas while you're sleeping -- and when you total it all up, including your nocturnal gas-passing, you may fart an average of 14 times per day.

In fact, it's pretty normal for one person to pass between one and four pints of gas (about an eighth to a half a gallon) in the course of just one day -- and that means we're all passing somewhere between 13 to 21 farts per day [source: Kluger, The Merck Manual].

6: Talking While Eating, Chewing Gum or Smoking Can Give You Gas

Flatulence is made up of five gases: carbon dioxide, hydrogen, oxygen and sometimes methane -- and when it's caused by excess air in the colon, you'll also find nitrogen in the mix. How, exactly, does excess air get into a colon? Well, you swallow it. Swallowing air causes flatulence, and good luck avoiding that while you talk or chew. The best you can do is chew slowly when eating (and especially when chewing gum) and avoid talking while you eat to keep excess air from building up in the stomach whatever gas doesn't go up (belching) will go down into the colon, destined to become a fart.

Smoking, too, increases flatulence -- although the exact reason flatus is a side effect of smoking isn't known. Some theorize it's irritation in the GI tract that causes smokers to pass more gas than non-smokers, but the more common theory suggests it's all that air smokers swallow while smoking that's doing it.

The foods we eat directly impact how frequent -- and how odorous -- our flatus will be.

Dairy products, for example, cause flatulence in people who don't produce enough lactase, an enzyme needed to digest milk sugars. Fructose (including high-fructose corn syrup), table sugar and artificial sweeteners such as sorbitol also all pass undigested through the digestive tract and can cause excessive gassiness upon reaching the colon.

If the body's digestive system can't easily absorb a food, the undigested food has time to ferment in the colon, and when that happens you've got gas -- smelly gas. While the foods that affect you may differ than those that affect others, at the heart of the fart you'll find carbohydrates -- that's fiber, starches and sugars -- are usually the major culprit.

4: Higher Altitude Means More Gas to Pass

We fart more when we fly. It's true -- and it has to do with the law of physics known as the ideal gas law.

High-altitude flatulence has to do with a change in atmospheric pressure and altitude. Airplane cabins are pressurized to be the equivalent to about an 8,000-feet altitude (which is a cruising altitude of about 565 mmHg) -- a significant pressure change for the human body, considering the pressure we're used to living on the ground is 760 mmHg. When the atmospheric pressure in the cabin decreases, the volume of intestinal gas in your bowels increases, and a greater volume of intestinal gas means you're going to pass more of it.

Remember: Half of the air in the airplane cabin is recirculated air, so break wind at the risk of your own (and your seatmate's) nose.

3: Farts Really Are Flammable

On a German dairy farm, methane produced by the farts of 90 cows built up in a shed and, after a spark, caused a fire in 2014 [source: Kirschbaum]. Yes, farts really are flammable. And not just cow flatulence human flatus is, too.

Flatulence is a combination of carbon dioxide, hydrogen, nitrogen, oxygen and methane. Two of these gases are flammable -- methane (did the cow story tip you off?) as well as hydrogen sulfide, which means, yes, technically you really can light your farts on fire. (But please don't.)

2: Hormone Fluctuations Can Give You Gas

Some women experience abdominal bloating (distention) and gas during their menstrual cycle, due to fluctuating hormone levels. Specifically, we're looking at you, ovarian hormones.

While fingers are usually pointed at progesterone as the hormone behind menstruation-related gastrointestinal problems, the inner lining of your stomach and small intestine contain estrogen receptors. Rising levels of estrogen have been found to mess with how well your GI tract does its job -- it slows things down, causing a build-up of air and gases in the intestinal tract, constipation and flatulence. (Testosterone does not seem to be linked to gassiness.)

Additionally, you'll find yourself farting more frequently if you develop problems with your pancreas, which produces the hormones and enzymes your body needs to properly break down the foods you eat.

1: There's Such a Thing as Odor-eating Underwear

Intestinal gas deodorizing products -- odor-eating underwear -- were originally made for people suffering from digestive problems, such as Crohn's disease or food intolerances, or those who have undergone gastric bypass. But anyone can use them if you're a high-tech tooter, consider a pair of flatulence-filtering underwear.

Odor-controlling underwear does just what you think it does filters out odors -- and some claim to be able to filter out sulfur compounds with odors 200 times as strong as what your average fart smells like [source: Shreddies, Ltd.]. That's a pretty strong smell.

Most of these products are made with specially-designed activated carbon fiber fabric (others rely on ceramic particles, instead), although there are also activated charcoal-lined pads or panels . Briefs? Thong? Insert-only? It's all available, but keep in mind the more coverage the better: Briefs made with carbon fiber fabric are your best chance against even the smelliest of farts, while pads only seem to be good for filtering up to about 77 percent of those odors [source: Ohge].

Author's Note: 10 Fascinating Facts About Flatus

Of all the fascinating facts about farts I found, these two may have been my favorite: Each of those 13 to 21 daily farts may travel as fast as 10 feet per second, and the temperature of a newly formed fart is the same as your body temperature: 98.6 degrees Fahrenheit. You're welcome.

Gas, Bloating: Always Uncomfortable?

Upset stomach got you down? Gas, bloating, and bathroom problems are a constant battle for many people -- often the symptoms are related to diet, but there are some more serious medical conditions that may be the culprit.

Most people know that beans, broccoli, and onions can cause gas, but what most people don't suspect are fruits, sodas, and milk. Fructose (a sugar found in fruits and sodas) and lactose (a sugar found in dairy products) are common causes of gas, bloating, abdominal cramps, and diarrhea.

Lactose intolerance is extremely common. It is estimated that 30 to 50 million Americans have some degree of lactose intolerance. Certain racial and ethnic populations are more affected than others, including 75% of African Americans, Jews, Hispanics, and Native Americans, and 90% of Asians.

Fructose intolerance is also common, but less recognized. A study presented at the annual meeting of the American College of Gastroenterology in Seattle by University of Kansas researcher Peter Beyer, RD, finds that nearly half of normal people get gas from fructose. This common fruit sugar is found in fruit juice and is used as a sweetener in some soft drinks.


Experts suggest that you keep a diary of foods that you eat and their relation to your symptoms and take that information to your doctor. Careful review of diet and the amount of gas passed may help relate specific foods to symptoms and determine the severity of the problem.

In addition, there are tests your doctor can perform to diagnose lactose and fructose intolerance. In fact, because of how common it is, Beyer suggests that people with these symptoms should get breath tests to see if fructose is the root cause of the problem.

But other researchers think that many cases of gas, bloating, and bathroom problems may be related to another condition: irritable bowel syndrome (IBS).

Mugdha Gore, PhD, an independent researcher based in Philadelphia, has studied the issue. In a survey of more than 650 people diagnosed with intestinal disorders, she found that the majority had IBS -- and were getting no relief from medications.


She presented her report this week at the annual meeting of the American College of Gastroenterology in Seattle.


Indeed, IBS is one of the most common intestinal disorders, and can be difficult to diagnose, says Gore. For many people, the symptoms alternate frequently. While gas and bloating are the constants, there may be abdominal pain or discomfort, plus altered bowel habits -- people may be constipated one week, have diarrhea the next, or have a sudden urge to have a bowel movement. The pattern varies from person to person, she says.

Experts don't know the exact cause of IBS, but suspect it may be triggered by stress, hormones, and nerve signal disruptions in the brain.

Many people with mild cases don't ever see a doctor for their problem. "There's much controversy about whether this is a real disease," Gore tells WebMD. "It's all about spastic colon. For some reason, in some people, the colon starts behaving erratically."

Prescription medications like Prilosec, Zantac, and Pepcid can "calm" the spasms that cause colon problems. Antidepressants seem to help control the pain, Gore adds. Pain, antidiarrheal, and anti-gas medications are available over the counter and there are two prescription therapies -- Lotronex and Zelnorm -- that may help some women with the disease.


But Gore's study found that these work for only one-third of gas-and-bloating sufferers. "Many more were saying that they weren't working," she tells WebMD.

Most people try to figure it all out on a trial-and-error basis, Gore adds. "Most patients alter their diets -- if they have constipation, they start eating a lot of fiber if they have diarrhea they stop drinking coffee, stop eating beans."

For some people, it's a quality-of-life issue, she says. "Some people have been suffering for a year. Some don't 'go' for weeks at a time. Some have had to miss a lot of workdays. People are suffering. The pharmaceutical companies need to get products developed for these people."

The worst-case scenario: gas and bloating might signal colon cancer or inflammatory bowel disease, but people with those conditions usually also experience weight loss, blood in the stool, and anemia, adds Radhika Srinivasan, MD, a gastrointestinal specialist and assistant professor of medicine at the University of Pennsylvania in Philadelphia.

Lean Proteins May Help Reduce Gas

Fat in your diet doesn't cause gas, but it can increase bloating and gas pains by delaying stomach emptying. The NDDIC recommends limiting fatty foods and emphasizing lean protein sources as a tactic for reducing your gassiness, because while fatty meats may cause gas, protein on its own doesn't stimulate gas during digestion. Instead of fatty steaks, pastries or fried appetizers, choose leaner alternatives such as baked or broiled fish, skinless white-meat chicken kabobs or sautéed tofu. Other lean protein sources you can snack on include edamame (steamed soybean pods) instead of nachos or you can keep fat levels down by seasoning protein-rich entrees with herbs and spices instead of heavy sauces or butter.

What Is Gas?

Building up and passing gas is part of life at any stage. The body sheds gas by burping it through the mouth or releasing it through the rectum. A person--menopausal or not--may require 14 efforts to pass 1 to 3 pints of gas daily. The odor of intestinal gas is attributed to its combination of hydrogen, nitrogen, oxygen, carbon dioxide and occasionally methane. Bacteria in the large intestine breaks down food substances into gas and adds the distinctive odor. That odor is no cause for health concern.

  • Building up and passing gas is part of life at any stage.
  • The body sheds gas by burping it through the mouth or releasing it through the rectum.

American Scientist

Having babies isn’t easy—and the standard explanation may be wrong.

Biology Evolution

This Article From Issue

November-December 2013

Volume 101, Number 6
Page 426

Humans are funny mammals. Among other things, we walk oddly (on two legs) and we have curiously big brains. We bear large babies with active and highly developed brains but with pitifully inept bodies. Despite what would seem evolutionarily unfavorable, one in 1,000 human mothers have a baby whose head is too big to fit through the birth canal, which necessitates a cesarean section, if medical care is available. Virtually all human mothers experience pain in childbirth, and delivery takes much longer than in other mammals. For example, in University of New Mexico researcher Leah Albers’s 1999 study of 2,500 full-term births, labor lasted on average almost nine hours for first-time mothers. In comparison, apes and monkeys generally give birth within two hours. Cross-culturally, assistance in childbirth is almost universal. Although evolution ought to favor low-risk, easy deliveries, this is not how it turned out for humans. To understand why, we need to consider advantages and disadvantages of more developed newborns, wider hips in the mother, and the metabolic demands on the mother.

Unlike other singly borne offspring, human babies cannot immediately get up, feed, and walk around like a newborn lamb. Nevertheless, human newborns’ brains are much more active than those of a litter of helpless newborn puppies, which are born with eyes that are closed shut and ears that cannot yet hear. Why are human babies born with comparatively active brains but helpless bodies, a unique phenomenon among mammals?

Photo at top, Mauro Fermariello/Science Source at middle, Ocean/Corbis at bottom, Organics image library/Alamy

Human newborns are unique among mammals in that, unlike other singly borne offspring, our babies cannot immediately get up, feed, and walk around like a newborn foal yet our newborns’ brains are much more active than those of a litter of helpless newborn pups with their eyes still closed and their ears unable to hear. Thus, in comparison to other animals born one at a time, human babies are born at an earlier developmental stage, before their bodies have developed enough to walk around.

This strange mélange of two basic adaptive strategies—an active brain with an inept body—is widely thought to have evolved because our unusually large brains and our peculiar, bipedal mode of getting around produce conflicting demands. This explanation is called the obstetrical dilemma. In humans, the size of the head of term fetuses is a tight fit for the mother’s bony birth canal. According to the obstetrical hypothesis, we need a wide pelvis to bear big-brained babies but a narrow one to walk or run efficiently. The compromise between these opposing needs is to carry babies as long as possible so that the brain can grow in utero and then—just before the baby’s head gets too big to fit through the birth canal—deliver the infant earlier relative to when other mammals deliver theirs.

The work of reproduction isn’t finished then. For the first year after birth, human babies continue to develop rapidly at a fetal rate in both brain size and body maturity—a risky strategy that calls for a great deal of investment by the mother. Not only must she grow the baby inside her womb for 9 months, but also she must continue to care for and protect the helpless infant for another 12 months after birth. She also continues to nourish the baby with breast milk, if we ignore the relatively recent invention of formula or other substitutes. To grow into big-brained adults, our mothers have to give us a great deal of care and feeding. Of course, fathers make genetic contributions to the baby and can ease the mother’s task substantially if they provide for or protect the mother of their offspring.

As Robert Martin quips in his new book, How We Do It, “We get our brains from our mothers,” genetic contributions from the father notwithstanding. What mothers do for their babies is meet their enormous metabolic needs, enabling baby brains to grow big before and immediately after birth.

The prolonged period of breastfeeding needed by a human baby is the most energetically demanding period of a female’s life. A mother may even allocate her own brain during pregnancy, losing some 4 percent of its volume, to meet the energetic demands of her baby’s brain. (The loss is regained, fortunately, in about six months.) Some have speculated that the reason female mammals are often much smaller in body size than males is so that the lifetime energetic needs of a female, who experiences metabolically demanding pregnancy and lactation, will equal those of a male.

Casting Doubt on a Paradigm

The obstetrical hypothesis postulates that the demands of an unusual locomotor system increase the risk and cost of the reproductive process. If this is the case, evolution would favor human birth at earlier stages of development than in other, nonbipedal primates, and mothers with wider hips would experience decreased motor efficiency.

The obstetrical dilemma hypothesis postulates that newborn brain size is limited by the disadvantages to the mother’s locomotion posed by wider hips. The energetics-of-gestation-and-growth hypothesis postulates that the baby’s head size is limited by the metabolic cost to the mother of carrying a large baby.

Illustration by Tom Dunne.

The obstetrical hypothesis is neat and readily comprehended, which helps explain its widespread acceptance, but new evidence casts doubt on it. A recent paper by Holly Dunsworth of the University of Rhode Island and colleagues reexamines the predictions and evidence supporting the obstetrical hypothesis and suggests an alternative explanation. For instance, human gestation is often said to be short relative to that of other primates, based on how much more growth is needed in neonates to achieve adult brain size. The shorter duration of gestation on first glance supports a prediction of the obstetrical hypothesis—that birth has evolved to occur earlier in hominids so that the baby is born before its head is too large to pass through the birth canal. Actually, the duration of human pregnancy (38–40 weeks) is absolutely longer than that of chimps, gorillas, and orangutans (32 weeks for chimps and 37–38 weeks for the latter two). When Dunsworth and her colleagues took maternal body size into account, which in primates is positively correlated with gestation length, they showed that human pregnancy is also relatively longer compared to that in great apes. No wonder that the third trimester seems so long to many pregnant women.

Another oft-cited fact supporting the obstetrical hypothesis is that, of all the primates, human newborns have the least-developed brains. Human babies’ brains are only 30 percent of adult size, as opposed to 40 percent in chimps. This difference in newborn brain size seems to suggest that human babies are born at an earlier developmental stage than other primates.

Compared with the heads of other primates, the head of a human newborn is a very tight fit through the birth canal. For the sake of comparison, the drawings are scaled so that the transverse diameters of the birth canals are the same.

Image adapted by Tom Dunne from K. Rosenberg and W. Trevathan, BJOG: An International Journal of Obstetrics and Gynaecology 109:1199.

The catch is that adult brain size in humans is much larger than in other primates for reasons having nothing to do with birth. This means that using adult brain size as a basis for comparing relative gestation length or newborn brain size among primates will underestimate human development. But as one of the collaborators with Dunsworth, Peter Ellison of Harvard University, pointed out in his 2001 book Fertile Ground, the relevant question is, Given how large a mother’s body size is, how big a brain can she afford to grow in her baby? It is an issue of supply and demand. Labor occurs when the mother can no longer continue to supply the baby’s nutritional and metabolic demands.

As Ellison puts it, “Birth occurs when the fetus starts to starve.” From this perspective, the brain size of a human newborn is not small for a primate but is very large—one standard deviation above the mean. Body size in human newborns is also large relative to other primates when standardized for a mother’s body size. Both facts suggest that pregnancy may push human mothers to their metabolic limits.

The obstetrical hypothesis, in contrast, suggests that locomotion rather than metabolism is the limiting factor in birth size. The underlying concept here is that wider-hipped women—capable of giving birth to larger offspring—should suffer a disadvantage in locomotion. But detailed studies of the cost of running and walking—including new work by Dunsworth’s coauthors Anna G. Warrener of Harvard University and Herman Pontzer of Hunter College—do not support this idea. Men and women are extremely similar in the cost and efficiency of locomotion, regardless of hip width. Enlarging the birth canal to pass a baby with a brain 40 percent of adult size, as is typical of newborn chimps, would require an increase in diameter of only three centimeters—just over an inch—in the smallest dimension of the birth canal. This wouldn’t hinder locomotion significantly, given that many women already have such broad hips. The conflict between big-brained babies and upright walking may be more conceptual than real.

What Does a Baby Cost?

Although the findings showing that human babies are not earlier than other primates are interesting, they still fail to identify what limits baby brain size. Dunsworth and her coauthors propose that the metabolic constraints faced by a mother limit the length of pregnancy and fetal growth. They have dubbed their hypothesis the energetics-of-gestation-and-growth hypothesis.

From the infant’s perspective (top), humans are born with less-developed brains than chimpanzees—supporting the obstetrical hypothesis. From the mother’s perspective, humans are born with large brains relative to chimpanzees (bottom)—supporting the energetics hypothesis. Holly Dunsworth and colleagues contend that because adult brain size in humans is much larger than in other primates for reasons having nothing to do with birth, using adult brain size as a basis for comparing primate gestation length or newborn brain size will underestimate that of humans.

Graphs adapted by Barbara Aulicino from H. Dunsworth, et al., Proceedings of the National Academy of Sciences of the U.S.A. 109:15212.

As the baby grows in both brain and body in the womb, its demand for energy accelerates exponentially. At some point, the mother reaches the limit of her ability to supply the fetus’s demands, and then labor begins. Even following birth, the big-brained, big-bodied newborn needs a loving mother who will continue to feed and care for it while its brain continues to grow at a fetal rate. In the womb, the fetus is basically part of the mother. Once born, the baby is effectively at a higher trophic level than its mother, like a parasite feeding on her, which increases the metabolic demands on her. However, the baby’s needs have shifted to include more long-chain fatty acids, which are key for brain growth. Since these are very efficiently transmitted to the baby through breast milk, rather than through the placenta, moving the baby outside the womb isn’t a problem.

The obstetrical hypothesis is not defunct it is simply under question. But merely convincing those who were raised intellectually within this paradigm to consider an alternative hypothesis can be challenging. When she gives a talk about the energetics hypothesis, Dunsworth summarizes a conversation that illustrates this challenge:

She’s right. Evolutionary adaptation doesn’t have to be perfect, just good enough. Perhaps the female pelvis adapted to fit the size of the human fetus’s brain, rather than the female pelvis’s limiting the baby’s brain size. Still, we are left with no clear reason why a baby is such a tight fit in the mother’s birth canal. Pelvic size may be limited by something not yet taken into account in locomotor studies, such as speed, balance, or risk of injury. Or, perhaps simple economy keeps pelvic size close to neonatal brain size. The third alternative is that human childbirth was not always difficult and has only become so as improvements in diet have increased newborn body size. The obstetrical hypothesis and the energetics hypothesis are not mutually exclusive.

The evolutionary conflict that makes human birthing difficult may not be between walking or running and having babies, but between the fetus’s metabolic needs and the mother’s ability to meet them. Perhaps the problem isn’t only having —bearing—a big-brained baby. Perhaps the real problem is making one.

The Anatomy of a Fart

Chemical Makeup of the Average Fart

● 59% nitrogen, 21% hydrogen, 9% carbon dioxide, 7% methane and 4% oxygen—all essentially odorless. (Less than 1% is what makes farts stink.)

The Stench Comes…

● …from minuscule amounts of ammonia, hydrogen sulfide and excrement, which can be smelled at 1 part per 100 million parts air.

The Gas…

● …that gives farts that special stench is hydrogen sulfide.

The More Sulfur-Rich…

● …your diet, the more your farts will stink.

Foods that…

● …cause your flatulence to reek include beans, cabbage, cheese, eggs and soda.

Beans, Cabbage…

● …mushrooms and onions cause a lot of gas because they contain complex sugars that your body can’t digest.

Throwin’ Heat

● Farts have been clocked at a speed of 10 feet per second.

Fill ’er Up

● 1 quart (or 600 ml) – the average amount of gas a guy with a relatively healthy diet lets out every day


● The average number of times each person rips one daily. Who would’ve thought?

● Women fart as much as men—they’re just not quite as proud of them.


● Temperature of a fart at time of creation

There Are Hundreds of Slang Terms…

● …for flatulence. Here are 10 of our favorites: ass biscuit, barking spider, bean blower, cheek flapper, crack splitter, death breeze, fog slicer, mud duck, spit a brick and strangling the stank monkey.

Cropdusting (from Urban Dictionary)

● The act of ripping a potent air bomb indoors, then moving briskly to the other end of the room to stay ahead of your own stench, which “dusts” the room with your flatulence in the process.

When in Rome

● Apparently we’re not the only civilization to appreciate the sounds of flatulence. Roman Emperor Elagabulus was known to punk his royal guests at dinner parties with a primitive version of the whoopee cushion. The modern version was re-invented in 1930 by employees of the JEM Rubber Co. who were experimenting with scrap sheets of rubber.


● The number of people to break the world record for sitting on whoopee cushions simultaneously (at a hockey game in Moline, Illinois)

Methane Myth

● Fart noise is generated by the flapping of butt cheeks, not by the fart itself.

3 Things That Crank Up the Decibels of an Ass Blast

2) The force with which it’s expelled

3) The tightness of the sphincter muscles

Sphincter Showdown: Vegetarians vs. Carnivores

● Vegetarians actually pass more gas it’s just quieter due to their larger stools and looser sphincter muscles.

Carnivores May…

● …have less gas but they blow a mightier horn thanks to their tighter sphincter muscles.

Got Gas?

● People who are lactose intolerant have been known to cause quite a stink upon consuming dairy products. Keep in mind that whey is a milk-based product. So if your lactose challenges are responsible for much reek, consider a nondairy protein supplement such as soy or hemp.

True or False?

● Can a flame be lit with flatulence? True. The art of fart-lighting (or blue-darting, zorching or gas lamping, as it’s also called) is the practice of setting fire to the gases from one’s backside, often producing a blue hue. But before you point that blowtorch toward your blowhole, know that many a dumbass has been burned by this asinine stunt.

Quick Tips to Reduce the Output

2) Eat slower. You’ll gulp less air and fart less often.

3) Stay calm. According to the Mayo Clinic, eating during stress can impede digestion.

The Bottom Line

If you're starting a new, low-carb diet, it's possible that you'll experience some uncomfortable side effects including gas and bloat.

Adding in more fiber to your diet will likely improve your digestive issues, but you'll need to be thoughtful about your approach. If your current fiber intake is extremely low, up your fiber slowly, and be sure to increase the amount of water you drink as you do so.

Without upping both water and fiber intake, you might just end up right back where you started: bloated and gassy.