>Why such a high prevalence of roundworm and whipworm infections? The scientists speculate that the monks may have picked up the parasites when putting feces to work as a fertilizer, either by emptying their own latrines to manure crops, or by bringing in outside fertilizer contaminated by parasites in human or pig excrement. These hands-on practices were definitely used in Medieval and Roman times, just as they are today in parts of the world where other fertilizer options are scarce.
No need to go to the 3rd world - there are plenty of places where eating raw lettuce is a bad idea. I went to a lecture once that went into detail on the lengths that the USA goes to to ensure our lettuce is safe to eat. The conclusion was that stuck with me was that the first time your lettuce leaves refrigeration is on the drive home, the speaker suggested that you bring a cooler in the trunk of your car to ensure proper cold chain management for leafy green purchases.
You can see some of the considerations in "Commodity Specific Food Safety
Guidelines for the Lettuce and
Leafy Greens Supply Chain" [1]
Here in India, the leafy greens are eaten very fresh, usually on the day of the harvest.
And, we don't usually buy greens from the supermarket where chikitshadhina even have a chance of maintainance, rather, we prefer to buy from Street side vendors.
> Sometimes, raw fruits and vegetables contain harmful germs that can make you and your family sick, such as Salmonella, E. coli, and Listeria. CDC estimates that germs on fresh produce cause a large percentage of foodborne illnesses in the United States. The safest produce to eat is cooked; the next safest is washed.
How large of a percentage? About 45.9% of US food poisoning in the US is attributed to produce (of which 11.7% fruit-nuts, 34.2% vegetables), vs 47.8% to animals (of which 6.1% seafood, 13.8% dairy, 6.0% eggs, 22.0% meat-poultry)[2].
I suspect there's quite a bit of risk-compensating behavior at work here. We tend to hear a lot more about the dangers of raw meat, eggs and seafood than of raw vegetables, which probably makes people much more wary about them.
I work for John Deere. One of my coworkers went to learn about lettuce production in the real world. He was in the field wearing gloves and a hair net for safety, and they were taking heads of lettuce off the plant and putting them directly into the plastic bag it would be sold from in the store. Then he looked up: wild birds were flying all over, and like bird do dropping poop behind. His conclusion: wash your lettuce.
(none of the above speaks for the company of course)
Are there effective best-practices to sanitize human waste for manuring? I’ve skimmed the “Humanure Handbook” which suggests a combination of composting (aerobic decomposition) and time (about one year). Are quicker and more energy-intensive options, like charring, equally effective at sanitization without removing plant nutrition?
Best practices are that you really shouldn't. The potential value of human waste as an additive to growing food is (vastly) overwhelmed by the potential for pathogen spread, pharmaceutical pollution, the whole nine yards.
The longest-running project I'm aware of is https://en.wikipedia.org/wiki/Milorganite , which is similar to what you are asking, if you want to go for a deeper dive in the subject.
Thanks! Had never heard of Milorganite. My interest is purely one of curiosity, specifically how waste might be recycled in a Mars or Moon colony. The Chinese regenerative life support project Lunar Palace 1 claims 41% nitrogen recapture from solid waste, using a "bioreactor" i.e. flippable compost bin:
Municipal sewage is pretty commonly added to green waste compost products, in an industrial facility the temperature can be brought up pretty high quickly so I don't reckon the process is more time consuming than processing any the green waste itself
Given how often animal manure was used as fuel for fires in the past, I'm surprised that most people didn't pre-burn their dried feces before using it as fertilizer.
I get why - it's too much extra work - but I would've figured it would be seen as worth it; provides fuel for fires, removes the stench, and makes it easier to spread on the crops.
(I know they weren't aware of germ theory, but even then I figured they would see advantages.)
Assuming the point is mostly nitrates and minerals, I don’t think they would be would be much affected, though the aggregation properties of the manure may be?
On the other hand, combustion could also help with destroying the antibiotics found in the manure, which spread to the soil and accumulate in produce.
>Complete elimination of pathogens from Human Solid Waste (HSW) is a priority of our biochar reactor. By heating an appropriate flow of input material to high temperatures above 450 C for about 15 minutes, the material thoroughly chars, causing a 100% elimination of pathogens.
Doesn't say anything about heavy metals or pharmaceuticals. In particular I don't know whether heat can denature or destroy birth control hormones like ethinylestradiol. If it's suspended in water, it can be removed through a reverse osmosis or activated charcoal filter. Maybe leaching before charring and filtering the runoff would help? Dunno.
> I'm surprised that most people didn't pre-burn their dried feces before using it as fertilizer
This paper is about incineration of sewage sludge. They consider incineration at temperatures like 700C to 900C. Seems like you end up burning 98% of the nitrogen, which is then released as gas (bottom of page 12, just before Conclusions). The output ash only contains 2% if the input nitrogen.
Kind of defeats to point of using the output as fertilizer.
You have to look at it in the context of the field, ~25-30 ish grave soil samples under fairly controlled conditions (e.g., burials in each group within about a km of each other, control soil samples taken from each grave, similar time period) ain't bad for paleo-helminthology. Sure, it leaves uncertainty in terms of conclusions but 'low quality' is a bit much.
Late response. I'm inclined to believe that the original paper, and the work done by the archeologists etc. is of the highest standard. The article itself was quite poorly written
But sure, do enough fine-scale examination of Medieval graves and you will find something interesting. That's kinda the point of archaeology/anthropology.
I'm more inclined to use a Bayesian approach here because we can't be certain about the probability of either population becoming infected. The 80% Credible Intervals for the two Beta distributions overlap: [1] and [2]. So indeed, the chance that either a monk or a normal villager would get infected by a parasite could be about the same.
I'm not sure if using Credible Intervals in this way is kosher, so someone feel free to critique. Ideally, if p is the unknown probability of a villager getting infected, and q is the unknown probability of a monk getting infected, then we need the posterior distribution of p-q. We have all the data needed to estimate this; you may use either simulations or characteristic functions to do it.
Barnards, which isn't as conservative as Fisher's exact. My understanding is Fisher's would be necessary if the number of positive cases was constrained (not applicable to this kind of work really but e.g. 600 years ago someone had ten eggs and distributed amongst the laypeople and the friars).
Barnard's test is appropriate here, because while the experimental design is a 2-way contingency table, only the columns (# villagers and # friars) are constrained, the rows (# infected/ # not infected) are not. P value was just under 0.05.
My gut feeling (pun intended) is that the manure theory makes sense and lower ranked monks were just more likely to rotate across all tasks needed in the friary, as opposed to peasants who specialised in a single activity (farmer, carpenter, quest NPCs, etc)
My understanding is that they analyzed remains from Cambridge cemetery, meaning they were probably city-dwelling people and not peasants, so less prone to agricultural works where you catch the worms.
While this is very interesting, sample size and variance is too small to be of significance. A less click-baity title would have been "why were medieval people so susceptible to worms"
The headline also over-generalizes the results: perhaps using human excement as fertilizer was more common at Cambridge, but the study did not look at other monasteries (or other Medieval time frames). I wonder whether there is a reason to expect that farming practices were shared between monasteries.
Finding worms in your excrement is pretty distressing in modern times even with cause and treatment clearly understood, it must have been vastly more so when the only aetiology was based on the cockamamie humours model, and treatments were so haphazard. The same is true for many other diseases of course, but there is something especially and viscerally repulsive about worm parasites.
I wonder how repulsive it actually was to people 1000 or 5000 or 10000 years ago though. In the wild – especially in the tropics – intestinal parasites are incredibly common in mammals, presumably including our ancestors. The invention of cooking must have reduced the parasitic load among hominins, however, as well as the discovery of soap. Various cultural taboos on eating or handling specific types of animals almost certainly originate from the desire to avoid parasites as well. Also, base parasitic load is reduced for people living in cooler climates, so worm infections may have become more yucky to Europeans not as accustomed to them.
These days, despite soap and cooking capabilities, we are doing our best to reintroduce the occurrences by everyone out here licking their partners anus.
It seems like a majority of cases come from plants grown in fertilizer made from poop of humans or pigs, which keeps the cycle going. In Pre-agricultural times, never using fertilizer would imply intestinal worms would occur much more rarely in hunger gatherer tribes.
I'm actually surprised that parasitic infection rate with native parasites (where humans aren't an accidental host) was so low at 30% or less. That would mean the existing treatments were rather effective. Just for comparison, https://www.africaontheblog.org/one-billion-1000000000-negle... claims that half the world's population hosts at least one species of worms.
There could be many more reasons, for instance just the fact of being more grouped together then villagers next to them. Even though they had better sanitization they didn't have access to modern cleaning technology and also not the awareness of it's importance.
A shithole might be more sanitary than a group toilet if less are using it.
This doesn't really answer its own question though. Using human feces as fertilizer is a plausible method of transmission, but if the monks were doing this, surely the villagers were doing it too? Or is the difference that monks were communal and thus more likely to ingest each other's feces, while the, uhh, blast radius would be smaller for a single-family household?
It's possible that some men who sought out a life of close confinement with other men might have a proclivity for behaviors which might result in parasite transmission.
All it takes is one "If you are truly devoted, you'll eat this shit" and everyone gets worms...
In a monastery I wouldn't be surprised for such odd things to happen... It must be a pretty isolated life when all the praying is done, and isolated populations pick up weird habits...
That one route of infection, most typically pin worms.
Intestinal worms can transmitted a number of different ways, but it's commonly the oral-fecal contamination route where feces comes in contact with food (when feces are used as fertilizer) or water (poor waste management) which is consumed.
However, hookworm larva can penetrate intact skin. Step in a puddle with bare (or exposed feet) and you can get infected.
Yeah that's absolutely correct, creeping eruption where they just tour around under your skin like a game of snake is usually caused by species adapted to using other animal species as hosts.
You seem to have more of a handle on intestinal parasites and rational thinking in general than I can muster up right now.
They specifically sampled the dirt that fell into the abdominal cavity of these monks. Wouldn't a potential variable be whether those eggs may have actually been in the dirt above the body that then fell rather than being in the intestines of the monks when they died? It could be that the soil they were buried under had a higher parasite egg load than the soil used to bury the non-monks elsewhere.
I'll try to come back around and do some reading as far as what particular parasites the researchers identified and how they're transmitted/their life cycles when my brain fires up later today. If you've got the time and motivation to give me a head start though, it would be much appreciated.
Tangential related fun fact: the common stereotype of the pot belly not-so-bright southerner in America (often depicted in popular media near or around a swamp) has it's origins in hook worms: https://www.pbs.org/wgbh/nova/article/how-a-worm-gave-the-so...
I've read that intestinal worms were nearly universal in post-WW2 Japan due to use of human feces in vegetable farming. I would guess that to be the most obvious explanation anywhere.
Move to SE Asia and they are still quite common. It's pretty usual to "deworm" yourself with medicine 1 or 2 per year.
But I did a bit more reading on it and apparently infection rates are dropping fast and most cases are in rural areas. If you live in city, the infection numbers are pretty low.
For anyone curious, the (modern) guideline for humanure is to let it sit/compost for two years before using it, for the purpose of letting any parasites in it die. This is compared to 3-6 months for eg chicken manure (which is primarily, IIRC, about "mellowing" the fertilizer ie letting it undergo some chemical changes).
I have a delicious and baseless armchair theory that intestinal worms served as a great way to distribute gut bacteria among a close-sleeping community of humans.
I am not sure about these specific monks, but many would eat a minimal amount of meat (and it would typically be limited variety). They believed that giving up meat is a form of penance.
My theory is that the middens in medieval stone monasteries were better preserved and easier to analyze than the temporary mobile outhouse holes of yer typical villein. It's not that monks were more susceptible to parasites, but that their intestinal evidence was more available to researchers.
This is the most parsimonious explanation to me as well, unless there is a way to groundtruth egg preservation in each location, it seems quite likely that the proportion of eggs surviving 600-800 years will vary between locations.
This was an analysis of graves though, what individual people died with. I have no idea how or if burial rights were different for monks vs regular people. (both were probably christian, though there could well have been small differences which may or may not be significant.
Can't edit previous comment but - I tracked down the actual study, the soil was indeed from graves (right under the sacrum where the bowels were) and was compared to control samples by the head or feet of the grave. The friars were buried with clothes, the laypeople in shrouds so similar deal and the sites were a few hundred meters apart so about as well controlled as you could expect, I reckon.
I got an intestinal parasite (Ascaris -https://www.cdc.gov/parasites/ascariasis/index.html) while in University here in Canada. I was minding my business one day, I looked down into the toilet water, and there was a little wormy in my stool. I fished it out and went the ER. The doctor was fascinated cause I don't think they see this so often.
Who knows where I picked it up. The most likely culprit was the dorm cafeteria I was living in. With the open salad bars and the sharing of serving utensils, it is an ideal location to spread some fecal.
As far as I know, you can get some parasites (not sure about Ascaris specifically) just from walking around barefoot.
I know they aren't really that dangerous unless you have a really high worm load, or you're unlucky and one ends up in a part of your body where it doesn't normally live, but their lifecycle is thoroughly disgusting and terrifying. Definitely something I've stayed up at night freaking out about at a few points in my life.
No. the larvae that would infect humans aren't competent swimmers. If you are a little zooplankton predator like a copepod, there would be little L2 stage roundworm larvae of various species whipping about (after having hatched from eggs that came out of a larger predator's gut) trying to attract attention and get eaten so they could continue the lifecycle (often, they'd need to get eaten by at least one larger predator to mature).
There are Ascaris-like worms in water that can affect humans, see: Anisakis. But you wouldn't get infected by larvae in the environment, you'd have to eat undercooked fish that ate the zooplankton that ate the L2 worms and get infected through the gut once they are L3 stage.
Ah - Dracunculus aka guinea worm is a another you could get from water, but you'd need to actually drink the copepods.
The Dune-sized worm in the room is how the religion of these friars assesses these findings?
Why is it important? Because they coded the moral and cultural foundation of the Western world. How could they be right regarding, say, whom you should marry (or the fact that you should marry at all with just a single person of your opposite sex), but be clueless regarding intestinal worms? Furthermore, how could they keep the pretense?
My first thought was diet. Monastic orders typically progressed from austere origins towards outright decadence when compared to normal folk. Monks could have been eating all manner of unhealthy foods (e.g. Mett in Poland and Germany) that other people seldom or never ate.
Using poop as fertilizer is certainly a vector for parasites, but one that people outside of monastic orders were also subject to.
113 comments
[ 3.6 ms ] story [ 210 ms ] threadYou can see some of the considerations in "Commodity Specific Food Safety Guidelines for the Lettuce and Leafy Greens Supply Chain" [1]
[1] https://www.fda.gov/files/food/published/Commodity-Specific-...
And, we don't usually buy greens from the supermarket where chikitshadhina even have a chance of maintainance, rather, we prefer to buy from Street side vendors.
I don't understand what he meant though.
> Sometimes, raw fruits and vegetables contain harmful germs that can make you and your family sick, such as Salmonella, E. coli, and Listeria. CDC estimates that germs on fresh produce cause a large percentage of foodborne illnesses in the United States. The safest produce to eat is cooked; the next safest is washed.
How large of a percentage? About 45.9% of US food poisoning in the US is attributed to produce (of which 11.7% fruit-nuts, 34.2% vegetables), vs 47.8% to animals (of which 6.1% seafood, 13.8% dairy, 6.0% eggs, 22.0% meat-poultry)[2].
I suspect there's quite a bit of risk-compensating behavior at work here. We tend to hear a lot more about the dangers of raw meat, eggs and seafood than of raw vegetables, which probably makes people much more wary about them.
[2] https://wwwnc.cdc.gov/eid/article/19/3/11-1866-t1
[1] https://www.cdc.gov/foodsafety/communication/steps-healthy-f...
(none of the above speaks for the company of course)
The longest-running project I'm aware of is https://en.wikipedia.org/wiki/Milorganite , which is similar to what you are asking, if you want to go for a deeper dive in the subject.
https://en.wikipedia.org/wiki/Yuegong-1
https://pubmed.ncbi.nlm.nih.gov/27912029/
It's unclear from the published results whether the crew ate food grown from this compost, or just measured the output's nitrogen content.
I get why - it's too much extra work - but I would've figured it would be seen as worth it; provides fuel for fires, removes the stench, and makes it easier to spread on the crops.
(I know they weren't aware of germ theory, but even then I figured they would see advantages.)
On the other hand, combustion could also help with destroying the antibiotics found in the manure, which spread to the soil and accumulate in produce.
https://www.susana.org/_resources/documents/default/2-1832-2...
>Complete elimination of pathogens from Human Solid Waste (HSW) is a priority of our biochar reactor. By heating an appropriate flow of input material to high temperatures above 450 C for about 15 minutes, the material thoroughly chars, causing a 100% elimination of pathogens.
Doesn't say anything about heavy metals or pharmaceuticals. In particular I don't know whether heat can denature or destroy birth control hormones like ethinylestradiol. If it's suspended in water, it can be removed through a reverse osmosis or activated charcoal filter. Maybe leaching before charring and filtering the runoff would help? Dunno.
Cow and horse feces look pretty different from human feces, drier and "herbal", and I would be surprised if they share the same combustive properties.
Sheep/goat/rabbit also seem naturally much drier than human tho I've never investigated their internals :)
Edit: on a second thought, cow shit is not particularly dry
[1] https://www.amazon.in/Fresh-Cakes-Religious-Purpose-Handmade...
- Burning cow dung cake in your holy function icrease positive energy and kill all bacteria and germs and purify air also .
https://en.wikipedia.org/wiki/Dry_dung_fuel: “Dry dung fuel (or dry manure fuel) is animal feces that has been dried in order to be used as a fuel source.”
This paper is about incineration of sewage sludge. They consider incineration at temperatures like 700C to 900C. Seems like you end up burning 98% of the nitrogen, which is then released as gas (bottom of page 12, just before Conclusions). The output ash only contains 2% if the input nitrogen.
Kind of defeats to point of using the output as fertilizer.
https://sci-hub.se/https://doi.org/10.1021/acs.energyfuels.5...
Is that really worth publishing?
Do enough random microscopy on enough cemetaries and you have a tale to tell every time.
I'm not really convinced there's an actual story here.
But sure, do enough fine-scale examination of Medieval graves and you will find something interesting. That's kinda the point of archaeology/anthropology.
But even than the magnitude of the observed effect is so noisy ( large type m error)
I'm more inclined to use a Bayesian approach here because we can't be certain about the probability of either population becoming infected. The 80% Credible Intervals for the two Beta distributions overlap: [1] and [2]. So indeed, the chance that either a monk or a normal villager would get infected by a parasite could be about the same.
I'm not sure if using Credible Intervals in this way is kosher, so someone feel free to critique. Ideally, if p is the unknown probability of a villager getting infected, and q is the unknown probability of a monk getting infected, then we need the posterior distribution of p-q. We have all the data needed to estimate this; you may use either simulations or characteristic functions to do it.
[1] - https://www.wolframalpha.com/input?i=Beta%2812%2C9%29+distri...
[2] - https://www.wolframalpha.com/input?i=Beta%289%2C18%29+distri...
11/19 Monks
8/25 Commoners
One bad meal could swing those numbers and adding to that the monks were more communal than individual families so more likely to affect them all.
https://www.cnn.com/2017/11/22/health/north-korea-defector-p...
Projecting much?
But clearly not "everyone" is doing it and I strongly doubt a majority is.
There could be many more reasons, for instance just the fact of being more grouped together then villagers next to them. Even though they had better sanitization they didn't have access to modern cleaning technology and also not the awareness of it's importance.
A shithole might be more sanitary than a group toilet if less are using it.
https://pubmed.ncbi.nlm.nih.gov/19653954/
It's possible that some men who sought out a life of close confinement with other men might have a proclivity for behaviors which might result in parasite transmission.
In a monastery I wouldn't be surprised for such odd things to happen... It must be a pretty isolated life when all the praying is done, and isolated populations pick up weird habits...
> Worm in intestine
> Eggs deposited near butthole
> Causes an itchy arse, which people itch
> Eggs on fingers. Eggs are sticky and not easily washed.
> Fingers touch food being prepared.
> People eat food.
I suspect therefore that communal food preparation (ie. one person prepares everyone's food, perhaps on a rota) is the main cause of this.
Intestinal worms can transmitted a number of different ways, but it's commonly the oral-fecal contamination route where feces comes in contact with food (when feces are used as fertilizer) or water (poor waste management) which is consumed.
However, hookworm larva can penetrate intact skin. Step in a puddle with bare (or exposed feet) and you can get infected.
typically confined to the dermis though and don't penetrate to the gut to complete the lifecycle. Luckily
They specifically sampled the dirt that fell into the abdominal cavity of these monks. Wouldn't a potential variable be whether those eggs may have actually been in the dirt above the body that then fell rather than being in the intestines of the monks when they died? It could be that the soil they were buried under had a higher parasite egg load than the soil used to bury the non-monks elsewhere.
I'll try to come back around and do some reading as far as what particular parasites the researchers identified and how they're transmitted/their life cycles when my brain fires up later today. If you've got the time and motivation to give me a head start though, it would be much appreciated.
But I did a bit more reading on it and apparently infection rates are dropping fast and most cases are in rural areas. If you live in city, the infection numbers are pretty low.
Who knows where I picked it up. The most likely culprit was the dorm cafeteria I was living in. With the open salad bars and the sharing of serving utensils, it is an ideal location to spread some fecal.
Suffice to say, I now avoid salad bars.
I know they aren't really that dangerous unless you have a really high worm load, or you're unlucky and one ends up in a part of your body where it doesn't normally live, but their lifecycle is thoroughly disgusting and terrifying. Definitely something I've stayed up at night freaking out about at a few points in my life.
There are Ascaris-like worms in water that can affect humans, see: Anisakis. But you wouldn't get infected by larvae in the environment, you'd have to eat undercooked fish that ate the zooplankton that ate the L2 worms and get infected through the gut once they are L3 stage.
Ah - Dracunculus aka guinea worm is a another you could get from water, but you'd need to actually drink the copepods.
I think its just a couple hookworm species that'll get in through your feet
Why is it important? Because they coded the moral and cultural foundation of the Western world. How could they be right regarding, say, whom you should marry (or the fact that you should marry at all with just a single person of your opposite sex), but be clueless regarding intestinal worms? Furthermore, how could they keep the pretense?
Using poop as fertilizer is certainly a vector for parasites, but one that people outside of monastic orders were also subject to.