- It takes dogs, people and elephants about the same time to excrete, despite the huge size difference
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- The ancient Chinese
- practiced copromancy, the diagnosis of health based on the shape, size and texture of faeces.
- So did the Egyptians,
- the Greeks
- and nearly every ancient culture.
- Even today,
- your doctor may ask
- when you last had a bowel movement
- and to describe it in exquisite detail.
- Sure,
- it's uncomfortable to talk about.
- But that's where science comes in,
- because what we don't like to discuss can still cause harm.
- Irritable bowel syndrome, inflammatory bowel disease, gastrointestinal infections and other poop-related ailments cost Americans billions of dollars annually.
- But trying to stem these problems was not our main motivation
- for trying to figure out some of the physics of defaecation.
- It was something else,
- much more sinister.
- Most elephants and other herbivores create "floaters" while most tigers and other carnivores create "sinkers"
- When parenthood hits, it hits hard. One of us is a working dad who survived by learning a new set of skills, one of which was faecal analysis.
- Years of nappy changes and then potty training turned me from a poo-analysis novice to a wizened connoisseur.
- My life passes by in a series of images: hard faeces pellets like peas to long faeces like a smooth snake to a puddle of brown water.
- Unlike the ancients,
- we didn't believe that we could predict the future from children's stool. But we did think it was worth trying to understand where all these shapes come from. Having a laboratory to answer questions about the everyday world is one of the distinct pleasures of being a scientist.
- As fluid dynamicists, we joined forces with colorectal surgeon Daniel Chu, and two stalwart undergraduates, Candice Kaminski and Morgan LaMarca, who filmed defaecation and hand-picked faeces from 34 mammalian species at Zoo Atlanta in order to measure their density and viscosity.
- 66% of animals take between 5 and 19 seconds to defaecate
- We learned that most elephants and other herbivores create "floaters" while most tigers and other carnivores create "sinkers". Inadvertently, we also ranked faeces from most to least smelly, starting with tiger and rhino and going all the way to panda. The zoo's variety of animals provided us with a range of faecal sizes and shapes that served as independent pieces of evidence to validate our mathematical model of the duration of defaecation.
- We also placed the faeces in a device called a "rheometer", a precision blender that can measure the properties of liquid-like and solid-like materials such as chocolate and shampoo. Our lab shares two rheometers with Georgia Tech physicist Alberto Fernandez-Nieves. We have since categorized the rheometers as the "clean rheometer" and the "David Hu rheometer" – which has seen its fair share of frog saliva, mucus and faeces.
- What else did we learn? Bigger animals have longer faeces. And bigger animals also defaecate at higher speed. For instance, an elephant defaecates at a speed of 6cm/s, nearly six times as fast as a dog. The speed of defaecation for humans is in between: 2cm/s.
- Together, this meant that defaecation duration is constant across many animal species – around 12 seconds (plus or minus 7 seconds) – even though the volume varies greatly. Assuming a bell curve distribution, 66% of animals take between 5 and 19 seconds to defaecate. It's a surprisingly small range, given that elephant faeces have a volume of 20 litres, nearly a thousand times more than a dog's, at 10ml. How can big animals defaecate at such high speed?
- Our defaecation data helped us design an adult nappy for astronauts
- The answer, we found, was in the properties of an ultra-thin layer of mucus lining the walls of the large intestine. The mucus layer is as thin as human hair, so thin that we could measure it only by weighing faeces as the mucus evaporated. Despite being thin, the mucus is very slippery, more than 100 times less viscous than faeces.
- During defaecation, faeces moves like a solid plug. Therefore, in ideal conditions, the combined length and diameter of faeces is simply determined by the shape of one's rectum and large intestine. One of the big findings of our study was that faeces extend halfway up the length of the colon from the rectum.
- Putting the length of faeces together with the properties of mucus, we now have a cohesive physics story for how defaecation happens. Bigger animals have longer faeces, but also thicker mucus, enabling them to achieve high speeds with the same pressure. Without this mucus layer, defaecation might not be possible. Alterations in mucus can contribute to several ailments, including chronic constipation and even infections by bacteria such as C. difficile in the gastrointestinal tract.
- Beyond simply following our scientific curiosity, our measurements of faeces have also had some practical applications. Our defaecation data helped us design an adult nappy for astronauts. Astronauts want to stay in space suits for seven days, but are limited by their nappies. Taking advantage of the viscosity of faeces, we designed a nappy that segregates the faeces away from direct contact with skin. It was a semifinalist in the NASA Space Poop Challenge earlier this year.
- It just shows that physics and mathematics can be used everywhere, even in your toilet bowl.
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- Duk da girman kashin giwa, lokaci daya yake fita da na mutum da kuma na kare
- Kusan tsawon lokaci daya mutane da karnuka da giwaye ke dauka wajen yin kashi duk kuwa da babban bambancin girmansu, David Hu da Patricia Yang sun yi mana nazari domin gano abin da ya sa haka.
- Mutanen kasar Sin (China) na zamanin da
- suna amfani da tsarin gano rashin lafiyar da ke damun mutum ta hanyar nazarin yadda kashinsa yake, kamar girma da siffa da kuma yanayin tauri ko laushin kashin.
- Haka su ma mutanen Misra
- da Girkawa
- da kusan duk al'ummomin zamanin da suna amfani da irin wannan tsari wajen gane irin larurar da ke damun maras lafiya.
- Hatta a zamanin yau,
- likitanka zai iya tambayarka,
- lokaci na karshe da kaje bandaki,
- da kuma yadda ka yi kashin da yadda launi ko kamanninsa yake, ka yi masa bayani dalla-dalla.
- Ba shakka
- wannan ba abu ne da kowa zai iya sakin jiki ya yi magana a kansa ba,
- to amma a nan ne maganar kimiyya ta shigo ciki,
- domin abin da ba ma son mu yi magana a kai shi ne zai iya cutar da mu,
- kamar yadda bincike ya nuna cewa cutukan da suka shafi kashi, kamar su gudawa da sauransu na jawowa Amurkawa asarar dimbin kudade a duk shekara.
- Sai dai a nan ba wai yadda za a shawo kan irin wadannan matsaloli ba ne babban abin da muka sa a gaba ba,
- game da yadda ake yin kashi ba.
- Wani abu ne na daban,
- wanda ya ma fi matsala.
- N/A
- N/A
- Tsawon lokaci na samu kaina a aikin nazarin yadda halittu ke zuba kashinsu,
- inda na wasu ke kasancewa kamar kwallo ko kwayar wani abu, wasu kuwa nasu yana zama kamar maciji, ko kuma wani ruwan tabo.
- Ba kamar mutanen da ba,
- a yau mu ba mu yarda cewa za a iya hasashen gobe ba daga yanayin kashin yara. Amma kuma mun yarda cewa yana da kyau mu san dalilin da ya sa kowa ne kashi yake da siffarsa ta daban.
- A matsayinmu na masu nazari kan kimiyyar abubuwan da ke da ruwa, mun hada hannu da kwararren likitan hanji Daniel Chu, da wasu dalibai biyu Kaminski da Morgan LaMarca, wadanda suka dauki hoton bidiyo na lokacin da wasu dabbobi masu shayarwa 34 ke kashi da kuma tattara kashin nasu, a gidan namun daji na Atlanta, domin su yi nazari a kai.
- Mun gano cewa yawancin giwaye da sauran dabbobi masu cin ciyawa, kashinsu ruwa-ruwa ne, yayin da yawanci damisa da dabbobin da ke cin nama suke kashi dunkulalle.
- Haka kuma mun yi nazarin bambancin warin kashin dabbobin, daga wanda ya fi wari zuwa wanda ba shi da wari sosai. Tarin yawan dabbobin da ake da su a gidan namun dajin ya kuma ba mu damar iya nazari a kan mizanin da muka tsara na lokacin da dabba ke dauka tana kashi.
- Sannan mun kuma sanya kashin a wata na'ura da za ta iya auna yawan sinadarai masu ruwa da ke cikinsa da kuma wadanda ba na ruwa ba, wato na kwaya-kwaya.
- Abin da kuma muka fahimta a nan shi ne, manyan dabbobi suna kashi mai tsawo kuma cikin sauri. Misali giwa tana kashin da tsawonsa ya kai na santimita (centimeter) shida a tsawon a cikin dakika daya, wato kusan saurin linki shida a kan yadda kare yake yin kashinsa.
- Shi kuwa mutun yana kashinsa ne a tsakanin santimita (centimetre) biyu a cikin dakika daya.
- Gaba daya wannan na nuna cewa, tsawon lokacin da dabbobi ke dauka suna kashi kusan daya ne, wato kusan dakika 12 (da kari ko ragin dakika 7), duk da cewa yawan tarin kashin ya bambanta sosai.
- Kusan kashi 66 cikin dari na dabbobi suna daukar tsakanin dakika 5 zuwa 9 suna kashi. Abin mamaki wannan tsakanin lokacin ya yi kankanta, idan aka yi la'akari da cewa kashin giwa ya kai yawan lita 20, kusan linki dubu na kare. To amma ta yaya irin wadannan manyan dabbobi za su iya kashi da sauri haka?
- Amsar da muka gano tana tattare ne a abubuwan da ke cikin wani ruwa mai yauki mai kamar majina da ke jikin bangon babban hanji.
- Kaurin wannan ruwa ko majina kamar silin gashin mutum yake, siririntakar ta yi tsanani ta yadda sai dai mu iya auna shi ta hanyar auna kashin yayin da ruwan ke tashi a matsayin tiriri.
- Duk da sirintakar, ruwan yana da santsi sosai matuka. Hakan ne ya sa kashi yake fita da sauri. Saboda haka idan komai lafiya yake, tsawo da kuma kaurin kashi yakan dogara ne ga, yadda karamin hanji da kuma hanyar takashin mutum ko dabba suke.
- To idan muka hada tsawon kashi da kuma abubuwan da wannan ruwa mai santsi mai kamar majina ya kunsa, daga nan muke iya gane yadda halitta ke kashi.
- Manyan dabbobi suna da kashi mai tsawo, da kuma majina ko wannan ruwa mai kauri, ta yadda za su iya fitar da kashin da karfi kuma cikin sauri. Idan babu wannan ruwa mai yauki to da kashi ba zai iya yuwuwa ba.
- Idan aka samu wani sauyi a wannan majina ko ruwa da ke jikin bangon babban hanji, to za a iya samun matsaloli ko rashin lafiya da dama.
- Bayan burinmu na sanin kwakwaf na kimiyya, nazarinmu a kan yadda ake kashi yana da amfani a rayuwarmu ta yau da kullum.
- Domin ta wadannan bayanai ne muka iya tsara kunzugu na manya wanda 'yan sama-jannati ke amfani da shi, domin su 'yan sama-jannati suna son kasancewa sanye da kayan musamman irin na tafiya zuwa sararin samaniya amma kuma kunzugun da za su yi amfani da shi a kayan na kawo musu cikas kan hakan.
- To ta hanyar wannan nazari ne, inda muka yi amfani da sanin kaurin ruwan da ke cikin kashi, muka tsara kunzugun da yake hana kashi taba fatar mutum.
- Wannan kunzugu na musamman da muka yi ya zo matakin kusa da karshe na gasar hukumar kula da sararin samaniya ta Amurka, NASA, wadda aka yi a farkon shekaran nan.
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