10 Reasons Why Humans Are So Gross

Girl picking her nose.
Snot, boogers ... just one of the gross things humans deal with on a daily basis. (Image credit: Shutterstock)

Have you ever wondered why humans are so … gross? We burp, we smell, we sneeze — humans do disgusting things all day long. "Grossology — The Impolite Science of the Human Body," an exhibit featured at the Liberty Science Center in New Jersey until Sept. 23, makes it abundantly clear that, yes, we are gross, but being gross helps us to survive!

Exploring the science of gross can help us to understand why we get warts, why we fart and why we smell.


Your nose runs and gets "stuffed up." Some people pick those noses, and you sneeze all over the place. It's no surprise that boogers are one of the gross parts of being human. But boogers an important part of human health.

Dust mites, bacteria, pollen, ash, sand and a whole host of tiny pieces of unhealthy "stuff" are constantly swirling in the air you breathe. Thankfully, boogers help to filter out some of these particles, so that unhealthy stuff doesn't make it into the body. In addition to boogers, nose hairs also help to filter the air you breathe.


Everyone burps. Whether you discreetly burp after excusing yourself from the table, or if you belch loudly and proudly, everyone lets one go. Gases, primarily carbon dioxide — though other gases like methane and hydrogen can also collect — gradually build up in our stomachs. This gas can be inhaled when you eat and drink, or it can be in what you're consuming, like carbon dioxide in fizzy sodas. The gas gets trapped in the stomach by the esophageal sphincter, according to "Grossology — The Impolite Science of the Human Body."

As the gas continues to accumulate, it becomes harder and harder for the esophageal sphincter to keep it from escaping. The gas must escape to relieve the pressure that builds up in the stomach. So, when the gas builds up enough, it will push the esophageal sphincter open, resulting in a burp. And, for anyone who has experienced a burp (all of us), you know the relief that can come from reducing that stomach pressure.

Poop, of course

One of the grosser aspects of being human (though, of course, pooping is not unique to the human species), pooping is essential to your life. Pooping helps to rid the body of undigested food and bacteria, as well as other unnecessary debris. Eliminating waste is a huge part of life for creatures like humans. But poop can serve an even greater purpose. [How Much Do You Poop in Your Lifetime?]

Poop can also serve as a clue to your health. The appearance of your poop and any difficulties you might have in the act itself can be huge signals that something is wrong. Abnormal poops can help reveal infection, digestive issues and more. [5 Things Your Poop Says About Your Health]


Aside from the boogers themselves, sneezing, especially a loud, snot-slinging sneeze, is often thought of as, well, gross. But sneezing helps to keep unwanted invaders from getting into the body through the nose. Irritants like pepper and dust that get into your nose can be quickly expelled by sneezing. Sneezes can exit your nose at up to 100 mph (160 km/h) — that's fast!

This reaction also happens when your nasal membranes are infected with a virus like the common cold. Sneezing helps to keep your nose clear of potentially more harmful viruses and bacteria. While it's gross, sneezing is an important part of staying healthy.


There is always something going on in your stomach. Whether it's trying to tell you to eat, letting you know it's way too full, or burbling for another reason, there's never a dull moment in the human gut. And while it may be noisy, your stomach is up to some seriously important work.

By producing mucus, stomach acids and specific enzymes, the stomach helps your body to digest food and pull out needed nutrients. Additionally, the stomach stores food, allowing you to stay satiated in between meals.


Everyone seems to have a different annoyance with their skin. From ingrown hairs to easy bruising, pimples, moles, blisters, warts, etc., there is a seemingly endless list of things that can seem gross about our skin. But there are reasons why things like warts pop out on our skin.

Warts are caused by viruses that cause contagious bumpy growths on the skin. Moles are a cluster of cells that form and can even sprout hairs. Bacteria, oil in the skin called sebum and dead skin cells can clump up together in pores on the skin and cause white blood cells to collect — pus then forms the typical "whitehead" associated with pimples. When our skin gets hit but the skin isn't broken, a bruise can form when lower layers of skin are damaged and blood collects in the area. There is a long list of things that can go "wrong" with our skin, but understanding why it happens can help us to keep our skin healthy.


Vomiting is gross, and a painful part of life. When our stomach is too full, irritated, or if the body is trying to get rid of a virus or something more sinister, we throw up. But, although it is unpleasant, it is incredibly important.

For example, if someone accidentally swallows something poisonous or drinks too much alcohol, vomiting helps to get rid of as much of the offending substance as fast as possible. From food poisoning to a stomach virus, vomiting is a natural reflex that our body uses to protect itself.


Just like we all poop, we all also fart. Yes — all of us. When we eat and drink, gases like air and carbon dioxide come along with it. And, while some of these gases can be released through belching, some are released through flatulence. In fact, every day we produce quite a bit of flatulence — about 15 to 20 farts per day.

But farts are usually much smellier than burps and are therefore considered much grosser. This is because of bacteria. As food is digested and passes through the lower intestine, it encounters enormous varieties of bacteria. These bacteria help to process our food and, in doing so, produce another gas — hydrogen sulfide. This smelly gas is released with our farts.

Additionally, our farts might seem gross because of the sound that they make. That sound is a result of the skin around the anus vibrating from the gas passing through it.

We smell

Body odor is a part of life, and in modern times we've started to use deodorant to make sure that we smell fresh and clean every day. But why do we smell so bad?

While there are certain medical conditions that can contribute to a person's smell, body odor in general is caused by bacteria. Our sweat doesn't have a foul odor, believe it or not. But when bacteria consume sweat, they produce foul-smelling waste that causes us to stink. Additionally, the food that we eat can cause bad breath, and we all know how gross "morning breath" can be. This is caused by bacteria in our mouths that produce smelly waste while we sleep.


Our noses have appeared multiple times in this list, and that's because they do so many gross things! Although boogers are gross, dripping noses and swallowing snot can be even grosser. While we might sneeze out irritants in our nose, or boogers or nose hairs might catch them, slippery mucus helps to collect the rest.

Cilia, or microscopic hair-like structures, help to push mucus, a slippery, clear substance, toward the back of the nose. The mucus picks up irritants like dust and debris as it travels and, aside from sneezing, blowing our nose, picking our nose, or any other way we might get rid of snot, humans, on average, swallow about a quart (one liter) of snot every single day. This helps to prevent irritants from reaching your lungs.

Original article on LiveScience.


Chelsea Gohd joined Space.com as an intern in the summer of 2018 and returned as a Staff Writer in 2019. After receiving a B.S. in Public Health, she worked as a science communicator at the American Museum of Natural History. Chelsea has written for publications including Scientific American, Discover Magazine Blog, Astronomy Magazine, Live Science, All That is Interesting, AMNH Microbe Mondays blog, The Daily Targum and Roaring Earth. When not writing, reading or following the latest space and science discoveries, Chelsea is writing music, singing, playing guitar and performing with her band Foxanne (@foxannemusic). You can follow her on Twitter @chelsea_gohd.