Physiology

Feces are discharged through the anus or cloaca during defecation. This process requires pressures that may reach 100 millimetres of mercury (3.9 inHg) (13.3 kPa) in humans and 450 millimetres of mercury (18 inHg) (60 kPa) in penguins.^[6][7] The forces required to expel the feces are generated through muscular contractions and a build-up of gases inside the gut, prompting the sphincter to relieve the pressure and release the feces.^[7]

Fecal resistome

The "fecal resistome" refers to the entire gene pool found in human and animal feces responsible for conferring antimicrobial resistance.^[11][12] Antibiotics taken by humans and animals primarily leave the body through feces and urine, which contain antibiotic resistance genes (ARGs) that act as an environmental pollutant.^[13][14][15] These contaminants spread throughout the environment via agricultural processes, such as manure application, and human wastewater systems.^[16][17][18] When contaminated feces enter new ecosystems, their microbial population fosters horizontal gene transfer, dispersing ARGs to native microbes.^[16][19][20] ARGs remain in the soil resistome longer with manure use.^[11] Moreover, these genes persist chronically in the environment through co-resistance to metals, where these long-lasting metals continue to act as a selective pressure to maintain resistance.^[21][22] Even without antibiotic contamination, fecal matter alters soil composition, fueling the growth of pre-existing resistant bacteria.^[23]

Fertilizer

The feces of animals, e.g. guano and manure, often are used as fertilizer.^[37]

Energy

Dry animal dung, such as that of camel, bison and cattle, is burned as fuel in many countries.^[38]

Animals such as the giant panda^[39] and zebra^[40] possess gut bacteria capable of producing biofuel. The bacterium in question, Brocadia anammoxidans, can be used to synthesize the rocket fuel hydrazine.^[41][42]

Coprolites and paleofeces

A coprolite is fossilized feces and is classified as a trace fossil. In paleontology they give evidence about the diet of an animal. They were first described by William Buckland in 1829. Prior to this, they were known as "fossil fir cones" and "bezoar stones". They serve a valuable purpose in paleontology because they provide direct evidence of the predation and diet of extinct organisms.^[43] Coprolites may range in size from a few millimetres to more than 60 centimetres.

Palaeofeces are ancient feces, often found as part of archaeological excavations or surveys. Intact paleofeces of ancient people may be found in caves in arid climates and in other locations with suitable preservation conditions. These are studied to determine the diet and health of the people who produced them through the analysis of seeds, small bones, and parasite eggs found inside. Feces may contain information about the person excreting the material as well as information about the material. They also may be analyzed chemically for more in-depth information on the individual who excreted them, using lipid analysis and ancient DNA analysis. The success rate of usable DNA extraction is relatively high in paleofeces, making it more reliable than skeletal DNA retrieval.^[44]

The reason this analysis is possible at all is due to the digestive system not being entirely efficient, in the sense that not everything that passes through the digestive system is destroyed. Not all of the surviving material is recognizable, but some of it is. Generally, this material is the best indicator archaeologists can use to determine ancient diets, as no other part of the archaeological record is so direct an indicator.^[45]

A process that preserves feces in a way that they may be analyzed later is the Maillard reaction. This reaction creates a casing of sugar that preserves the feces from the elements. To extract and analyze the information contained within, researchers generally have to freeze the feces and grind it up into powder for analysis.^[46]

Other uses

Animal dung occasionally is used as a cement to make adobe (mudbrick) huts,^[47] or even in throwing sports, especially with cow and camel dung.^[48]

Kopi luwak, or civet coffee, is coffee made from coffee beans that have been eaten and excreted by Asian palm civets (Paradoxurus hermaphroditus).^[49]

Giant pandas provide fertilizer for the world's most expensive green tea.^[50] In Malaysia, tea is made from the droppings of stick insects fed on guava leaves.

In northern Thailand, elephants are used to digest coffee beans in order to make Black Ivory coffee, which is among the world's most expensive coffees. Paper is also made from elephant dung in Thailand.^[50] Haathi Chaap is a brand of paper made from elephant dung.

Dog feces was used in the tanning process of leather during the Victorian era. Collected dog feces, known as "pure", "puer", or "pewer",^[51] were mixed with water to form a substance known as "bate", because proteolytic enzymes in the dog feces helped to relax the fibrous structure of the hide before the final stages of tanning.^[52] Dog feces collectors were known as pure finders.^[53]

Elephants, hippos, koalas and pandas are born with sterile intestines, and require bacteria obtained from eating the feces of their mothers to digest vegetation.

In India, cow dung and cow urine are major ingredients of the traditional Hindu drink Panchagavya. Politician Shankarbhai Vegad stated that they can cure cancer.^[54]

Etymology

The word faeces is the plural of the Latin word faex meaning "dregs". In most English-language usage, there is no singular form, making the word a plurale tantum;^[56] out of various major dictionaries, only one enters variation from plural agreement.^[57]

Synonyms

"Feces" is used more in biology and medicine than in other fields (reflecting science's tradition of classical Latin and Neo-Latin)

• In hunting and tracking, terms such as dung, scat, spoor, and droppings normally are used to refer to non-human animal feces
• In husbandry and farming, manure is common.
• Stool is a common term in reference to human feces. For example, in medicine, to diagnose the presence or absence of a medical condition, a stool sample sometimes is requested for testing purposes.^[58]
• The term bowel movement(s) (with each movement a defecation event) is also common in health care.

There are many synonyms in informal registers for feces, just like there are for urine. Many are euphemistic, colloquial, or both; some are profane (such as shit), whereas most belong chiefly to child-directed speech) or to crude humor (such as crap, dump, load and turd).

Feces of animals

The feces of animals often have special names (some of them are slang), for example:

• Non-human animals
  • As bulk material – dung
  • Individually – droppings
• Cattle
  • Bulk material – cow dung
  • Individual droppings – cow pats, meadow muffins, etc.
• Deer (and formerly other quarry animals) – fewmets
• Wild carnivores – scat
• Otter – spraint
• Birds (individual) – droppings (also include urine as white crystals of uric acid)
• Seabirds or bats (large accumulations) – guano
• Herbivorous insects, such as caterpillars and leaf beetles – frass
• Earthworms, lugworms etc. – worm castings (feces extruded at ground surface)
• Feces when used as fertilizer (usually mixed with animal bedding and urine) – manure
• Horses – horse manure, roadapple (before motor vehicles became common, horse droppings were a big part of the rubbish communities needed to clean off roads)

Feelings of disgust

In all human cultures, feces elicit varying degrees of disgust in adults. Children under two years typically have no disgust response to it, suggesting it is culturally derived.^[59] Disgust toward feces appears to be strongest in cultures where flush toilets make olfactory contact with human feces minimal.^[60][61] Disgust is experienced primarily in relation to the sense of taste (either perceived or imagined) and, secondarily to anything that causes a similar feeling by sense of smell, touch, or vision.

Social media

There is a Pile of Poo emoji represented in Unicode as U+1F4A9 💩 PILE OF POO, called unchi or unchi-kun in Japan.^[62][63]

Jokes

Poop is the center of toilet humor, and is commonly an interest of young children and teenagers.^[64]