If you’ve ever let one rip and silently thought to yourself “hey, this doesn’t smell too bad”, you’re not alone. Luckily (or rather — yuckily) enough, our farts actually smell quite alright — but only to ourselves. This isn’t just a myth or an attempt to downplay the stench we dealt. We are kinder in our judgment of flatulence when it’s our own. While we don’t exactly love our farts we certainly hate them less than others.

According to science, we become more habituated to our own farts. We get used to the bacteria that produce them, we get used to the smell, and we don’t dislike them as much. But there’s way more to farts than just this.

What is a fart?

Let’s be real, everyone farts. A fart is just the burp of the butt.

Our bodies have two primary and wonderful ways of passing excess gas — a byproduct of digestion — from our bodies. The primary, and more common way of passing gas is belching or burping. On average, a human burps around 30 or so times a day. Yes, that much.

The other and much fouler way of passing gas is via flatulence (or, as we regular folks say, farting). Farts are just gas. The burp of the butt is one of the body’s many wonderful ways of expelling excess gas from our systems.

When we fart, we don’t just let out one gas but rather a mixture of many. A typical fart lets out varying proportions of carbon dioxide, oxygen, nitrogen, and hydrogen. When you think about it, these are pretty innocuous everyday gases. As a matter of fact, apart from carbon dioxide (only at high concentrations), the rest don’t even have an odor to them.

What is it that makes farts stinky?

Contrary to (very) common belief, it isn’t methane that makes our farts smell. Another chemical element is to blame.

Ever notice your fart smelling like rotten eggs? Well, you’ve got sulfur to thank for that. Sulfur, an element in the oxygen family, is the gas to blame for any silent but violent stinkers.

The gas is present in a lot of the foods we eat. From leafy green cruciferous vegetables like brussel sprouts and cabbage to alcohols like beer and wine, all of them contain varying amounts of sulfur.

Sometimes, when we overindulge in sulfur-rich foods and drinks, our farts get extra stinky. This is because such foods in particular take a bit longer to break down and hang around in our digestive systems for longer. A byproduct of digesting such foods is the release of hydrogen sulfide by our gut bacteria. It is this form of sulfur that actually contributes to the stinky rotten-egg-like stench of our farts.

Although generally the culprit behind big ol’ stinkbombs, sulfur isn’t the only thing contributing to our farts. A study from 2021 revealed that a poor quality of life can also correlate with gastrointestinal issues such as flatulence in adults. The study sampled nearly 6,000 people aged 18 and above from three countries: the United States, the United Kingdom, and Mexico. Their findings revealed that nearly 83.1 percent of all adults sampled suffered from some sort of gastrointestinal problem that either related to or caused flatulence.

Lead author of the study, Professor Olafur Palsson, highlighted the correlation between gastrointestinal issues and an impaired quality of life. Turns out, farts can tell us a lot about our health.

“I think the most remarkable and surprising finding in our study is that almost all adults in the general population experience some daily gas-related symptoms. This is important given the data also clearly reveals that these symptoms affect people’s general wellbeing. Having a high amount of these common intestinal symptoms is associated with higher levels of depression, anxiety and stress, as well as impaired general quality of life,” said Palsson in a press release.

Why are our farts less stinky than others?

Let’s be real: everyone does it, but not all farts are equally stinky — especially if they’re not yours. Imagine you’re home alone and let one rip. Sometimes it’s just a bit of sound with no smell but other times, it may just be a real stinker. Despite the actual (terrible) smell of it, you don’t mind it too much. Contrast this to when we unfortunately smell someone else’s. We immediately skew our faces in disgust. It’s foul, vitriolic, and vile to the senses.

So what is it about our farts that make them more bearable than others? According to science, it might just be the fact that it’s yours.

Even when we can’t recognize our own odors, we still like them better than others

Centuries of human evolution have us primed to know ourselves. Simply put: Our sense of self — biologically speaking — is ridiculously well grounded even on a chemical level.

Think about it, smells and sounds that come out of us are intrinsically less threatening to us than those that come from someone else.

Way back in 1976, three researchers from the University of Pittsburgh conducted a particularly intriguing study that helped illustrate the role of chemical communication in self-recognition.

The researchers had 11 male grad students take part in blind smell tests. In these tests, the students were given 12 unpleasant body odor samples, 10 foreign, one control, and one of their own. As part of the test, students were asked to rate all samples and then attempt to pick out their own sample.

(Fun fact: Don’t feel too bad for the poor students. All male graduate students who partook in the test were compensated with a healthy sum of ten dollars. Not too shabby for smelling stuff.)

Although only three in 11 students could accurately identify the odor sample as their own, almost all students ranked their odor sample as less unpleasant (read: stinky) than others. Interestingly enough, a majority of the students also ranked unpleasant odors with unfavorable social traits. The students expected the people who donated the dankest samples to be unfriendly, dirty, and unpopular.

Basically, we don’t just favor our odor over others. We also associate terrible odors with terrible things.

Evolutionarily speaking, this makes a lot of sense. Think about it this way, when we smell something terrible — we don’t associate it with happy thoughts (unless that particular terrible smell is associated with pleasant memories). Take for instance blue cheese, if you’ve eaten blue cheese before and had a pleasant experience, you associate the stench of the cheese with positive memories. However, if you’re new to blue cheese stench, you’re not going to immediately run to take a bite.

The same logic applies to our farts. Even when we let out absolute stinkers — we know that they’re still our farts. They’re entirely distinctive to our bodies. Over time, we become habituated to them and can distinguish them from other people’s odors.

While we are kinder to our own farts we are overly harsh on others. This can be attributed to evolutionary mechanisms that relate negative chemical signals (like bad smell) from others with danger. This makes a lot of sense when we account for the fact that farts do contain disease-causing pathogens.

Flatulence and disease

Farting is a good thing! At the end of the day, it is just your body expelling excess gas. The problem lies, however, in the gnarly stuff we expel along with the gas. The gnarly stuff in question here is bacteria. Sometimes farts release bacteria known as Streptococcus pyogenes. This stuff can cause a whole range of diseases but more commonly causes strep throat.

So, although it is highly unlikely that smelling someone else’s flatulence can make you sick — it doesn’t take away from the fact that farts still do contain some potent pathogens that your body would rather not deal with. In essence, that’s likely why we react so violently to other people’s farts.

Ultimately, you might be one of the many in the world who really just don’t care about flatulence. You don’t care who dealt it, or that you smelt it. Farts, regardless of the source, aren’t that big a deal to you; you just don’t find them disgusting. Don’t worry, you’re not a weirdo — you’re just… adventurous?

We’re not kidding. There is a strange correlation between sensitivity to disgust and psychosocial variables like sociability. For instance, research has revealed that folks who are a bit more socially conservative tend to be more disgusted by farts whereas someone a bit more amenable, is less likely to be bothered or disgusted by a bit of gas.

Either way, whether you hate ’em or love ’em — your farts truly are just an extension of yourself.

Farting questions and answers