Although our sense of smell may not be as
highly developed as that of a dog, humans can smell a wide range of scents. A study in the journal Science found that
humans can discriminate at least 1 trillion odors. However, scientists are still trying to understand
how humans can distinguish between a “good” smell and a “bad” smell. One theory is that humans make this distinction
based on “chemical cues,” while another theory proposed by researcher Val Curtis is
that “our disgust toward certain sights and smells” is an “adaptation . . . that
evolved to keep us from coming into contact with infection and disease.” With this in mind, let us explore what literally
makes life stink in this episode of The Infographics Show, “Top 10 Worst Smells in
the World.” 10. Skunk Spray
Most of us have heard the stories about how bad skunk spray smells, and some of us have
had the unfortunate experience of smelling it firsthand. On Quora, one person who was sprayed by a
skunk at close range described the smell as “nauseating, noxious, putrid.” He added, “While your brain is trying to
process this sudden whiff of Hell that has engulfed your olfactory system, your eyes
will start pouring out tears, you may vomit, and you will become dizzy and disoriented.” What makes skunk spray smell so overwhelmingly
bad? According to the Iowa Department of Natural
Resources, the “primary stinky compounds are thiols and thioacetates, both rich in
sulfur—the same element that makes rotten eggs gag-inducing.” Sulfur atoms in these compounds form very
stable bonds with other atoms, which is why skunk odor is so hard to get rid of. An interesting side note reported by one source
is that thiols “happen to be highly flammable” too. 9. Lesser Anteater Spray
The lesser anteater is also known as the collared anteater and the southern tamandua. It is native to the forests of South America. Like the skunk, the lesser anteater emits
its stinky spray from its anal glands when it feels threatened. While the smell of skunk spray is bad, the
smell of lesser anteater spray is even worse. Some animal websites say it is about 4-7 times
stronger than skunk spray, while others say it is 5-7 times stronger. Despite its highly stinky spray, a few people
dare to keep lesser anteaters as exotic pets. 8. Titan Arum (Amorphophallus titanum)
This large flowering plant is native to Sumatra and western Java. A Live Science article states that titan arum
“plants typically can grow to a massive 8 feet (2.4 m) tall and the leaves can be
as big as 13 feet (4 m) wide.” It can take up to 7 years or longer for a
titan arum plant to bloom, yet the bloom lasts for only 24 to 36 hours. While the titan arum bloom may look like a
huge flower, it is actually what is called an inflorescence, which Live Science describes
as “a stalk with many flowers.” There is a good reason why the titan arum
is also called a “corpse flower.” While it blooms, it gives off a stench similar
to rotting flesh in order to attract carnivorous insects that will pollinate the flower. According to Live Science, the “smell and
the dark burgundy color of the corpse flower are meant to imitate a dead animal to attract
these insects.” A chemistry website called Compound Interest
states that several chemical compounds are responsible for the titan arum’s deathlike
odor. These include dimethyl trisulfide, dimethyl
disulfide, isovaleric acid, methylthiol acetate, and trimethylamine. Together these chemical compounds create a
dreadful combination of unpleasant scents – dead animal, garlic, sweaty feet, cheese,
and dead fish – that has earned the titan arum or corpse flower a spot on our list. 7. Rotten Food
Most of us have had the unpleasant experience of discovering old food that looks and smells
like a lab experiment. We are often in such a hurry to throw out
the rotting food that we don’t think what could cause its horrible odor. According to one science website, the scent
of rotting food “is most often due to the growth of spoilage microbes such as bacteria,
yeasts and mold.” The smell could be the result of chemicals
produced by the decomposition process, or they are “produced directly by the microbes
themselves.” Different spoilage microbes can produce different
odors. For example, molds can “give off musty,
earthy aromas” as they break down food, while “some yeasts produce sulfur compounds
that resemble human flatulence.” Some of the worst smelling foods in the world
are the product of intentional instead of accidental spoilage. For instance, Icelandic hákarl, which one
source describes as “rotten Greenland shark meat,” has an “overwhelming scent of ammonia.” The shark meat has to be allowed to rot or
“ferment” because fermentation lowers the toxin levels in the meat to a level safe
enough for human consumption. And then there is surströmming, which is
Baltic sea herring that “is fermented in barrels for six months.” The scent of this rotten fish is so bad that
the “official Swedish government actually recommends that the tins of surströmming
only be opened outdoors because of the massively-rancid stench.” 6. Garbage
The smell of garbage is often composed of many disagreeable odors caused by the decay
of disagreeable substances. Just think about all of the things people
throw out in the trash. Besides spoiled food, they toss out gross
stuff like used cat litter, dead rodents caught in mouse and rat traps, and paper towels and
rags used to clean up vomit, urine, and feces. Northern Colorado Disposal estimates that
18 billion used diapers are thrown away each year as well. Most garbage ends up in landfills where they
produce various foul-smelling gases. According to the New York State Department
of Health, “odors in landfill gas are caused primarily by hydrogen sulfide and ammonia,
which are produced during breakdown of waste material.” It notes that “hydrogen sulfide has the
foul smell of rotten eggs, while ammonia has a strong pungent odor.” These gases are not only smelly, but they
can create negative health effects as well. Exposure to high levels of hydrogen sulfide
and ammonia in the air “can cause coughing, irritation of the eyes, nose, and throat,
headache, nausea, and breathing difficulties.” 5. Human Feces
Knowing the physical components of human feces can help you understand why it smells so bad. While a “typical bowel movement” is about
75% water according to the GI Society, the “other 25% is a mixture of things” that
include “dead and living bacteria,” “food waste,” “undigested parts of foods,”
and “substances contributed by the intestines and liver, such as mucus and bile.” Besides waste products that your body can’t
break down, human feces can also contain smelly chemical compounds. It depends on what you eat. For instance, the GI Society notes that “meat
produces more smell than vegetables and intestinal bacteria produce several sulphur-containing
compounds” that produce smelly hydrogen sulfide. Other objectionable odors come from fatty
acids and skatole, “a product resulting from the naturally-occurring process of amino
acids being broken down in the intestine.” 4. Sewage
It is no surprise that raw sewage smells awful. If you thought your poop smelled bad, imagine
how bad the poop of thousands or even millions of people smells when it ends up in the sewer. Besides all that poop, raw sewage contains
things like urine, vomit, soap, cleaning products, used toilet paper, and wastewater from sinks
and showers. As bacteria break down some of the organic
components in raw sewage, they create sewer gas, which the City of Marion Water Pollution
Control Department describes as “a mixture of inorganic gases” that can include “hydrogen
sulfide, ammonia, carbon dioxide, methane, nitrogen, and hydrogen.” The department considers hydrogen sulfide
as the “odor culprit” that makes sewer gas smell bad. 3. Gangrene
Gangrene smells bad because it involves what the Mayo Clinic describes as the “death
of body tissue.” Some forms of gangrene involve bacterial infection,
which create wretched odors and toxins as the bacteria feed upon your tissue. The bacteria will eventually kill the tissue
if they are not stopped. An article about bad operating room smells
notes that “gas gangrene, in which bacteria infects and kills tissue with particular vigor,
reeks.” A medical student described the smell produced
by Fournier’s gangrene, a type of gangrene that affects the genital area, as “the worst
smell ever, like poop and sewage sludge and rot and dead stuff all rolled into one.” 2. Dead Human Body
If a small part of someone’s body reeks because it is being killed off by gangrene,
it is reasonable to think the smell of an entire dead body is many times worse. Even if you don’t see a dead human body,
you may be able to smell one if it has been decomposing long enough. Think of those accidental discoveries of dead
bodies because neighbors noticed an awful stench coming from someone’s house or from
the trunk of an abandoned car. One online magazine interviewed twenty people
who have smelled a dead body. From their descriptions, you can tell the
smell is quite revolting. One person described the smell as “rotten
eggs, feces, and a used toilet left out for a month x 1000,” while another person noted
a “very sharp, foul smell similar to horrible cheese mixed with the same smell you get from
a full trash can in the sun.” What makes us stink so bad after we die? Microbes breaking down our bodies are to blame. For instance, a Guardian article reports that
gut bacteria multiplies after we die because there is no functioning immune system to keep
them in check, and this bacteria literally eats us from the inside out. They “feed on the body tissues, fermenting
the sugars in them to produce gaseous by-products such as methane, hydrogen sulphide and ammonia,
which accumulate within the body, inflating (or ‘bloating’) the abdomen and sometimes
other body parts, too.” During the decomposition process, several
foul-smelling chemical compounds are also produced to create what one source calls the
“stench of death.” One of them is cadaverine, which is “responsible
for the foul smell of rotting flesh and is also found in urine and semen.” A second chemical is putrescine, which “smells
fairly similar to cadaverine” and contributes to bad breath odor. Finally, there are skatole and indole, which
are “major components of feces.” But that’s not all. According to a Daily Mail article, “researchers
have found a 'cocktail' of five chemical compounds given off by decomposing bodies that are unique
to human flesh when compared to other animals.” These compounds are called esters, which the
researchers described as “degradation products of muscles, fat tissue and carbohydrates.” The five esters have fruity smells. For instance, propyl hexanoate is a “chemical
used to recreate the smell of pineapples and blackberries,” while 3-methylbutyl pentanoate
has “a ripe apple odour.” However, these results are based on “small
tissue samples rather than whole bodies,” and it is possible that “decomposition in
the outside environment may also influence the smell.” 1. Other Dead Animals
Many other animals go through a process of decomposition similar to humans after they
die. The science journal Nature notes the presence
of “chemical byproducts such as ammonia, cadaverine, hydrogen sulfide, and putrescine”
as their bodies decay. Some animals that smelled bad in life smell
even worse than humans in death. For example, if you thought skunk spray was
bad, try getting a whiff of fresh skunk roadkill on a hot June day. You get a double whammy of smelly thiols from
the skunk spray and the odor of a rotting carcass baking in the sun. Other dead animals create an overwhelming
stench that can be worse than that of a dead human simply because of their large size. Dead beached whales are a good example. They are literally what one article calls
“tens of thousands of pounds of foul smelling, decomposing flesh.” According to forensic toxicologist Wolfgang
Weinmann, dead whales also bloat like other animals most likely because of putrefaction
and fermentation, and there have been some instances where whales will spontaneously
explode because of a heavy build-up of gases that form during the decomposition process. One well-known whale explosion occurred in
2004 in Tainan, Taiwan. BBC reported that “passers-by and cars were
soaked in blood and body parts were sprayed over a road after the bursting of the whale.” One resident remarked, "What a stinking mess. This blood and other stuff that blew out on
the road is disgusting, and the smell is really awful." Is there another bad smell that you think
should be added to this list? Let us know in the comments! Also, be sure to check out our other video
called Weapons Even The Military Made Illegal! Thanks for watching, and, as always, don’t
forget to like, share, and subscribe. See you next time!