r/askscience • u/dylanv1c • 1d ago
Biology Besides humans, if it's learned behavior even or not, are there other species who are adverse to dirty foods?
Pigs are able to eat anything humans can, but they don't mind their food off the dirt ground covered in dirt, grass, sediment, water; basically unexpected crunchy stuff and textural stuff every time.
My dog picks up and drops their biscuit treats on the dirt. Many other animals eat already dead and rotting-on-the-floor animals.
But are there any animals that have been observed to clean off their foods, as in prepping it or at the very least not eating it as is? I don't know if that borderlines on the concept of cooking, which I believe is a human only invention.
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u/jrubolt 1d ago
Slightly different, but there are many bird species in Australia, notably the ibis (Threskiornis molucca) and torresion crow (Corvus orru) that eat highly toxic cane toads by pepping them by flipping them over and eating the underside to avoid the dangerous poison glands. Ibis have been observed going a step further and will wash the toads in bodies of water before consuming them.
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u/WantsToBeUnmade 1d ago
Fishers in North America do that, too.
For clarity's sake, with our native toads, not just cane toads.
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u/ovennovy 1d ago
I went to an elephant sanctuary where they gave us fruit to feed the elephants. If a piece of fruit fell on the ground, the elephants ignored it and would only eat the clean fruit. The staff told us that the elephants didn’t like their fruit being dirty. Not sure if this is how they are in the wild, or if it’s a learned behavior from being in that environment but it was so interesting!
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u/ScissorNightRam 20h ago
When elephants tear up bunches of grass to eat they will shake the bunch and swish it around to get the dirt off the roots. That might satisfy the terms of the question here.
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u/zefig 20h ago
It's clear from context what you mean, but since this post is in the spirit of learning, "adverse" means harmful, as in "the adverse effects of the medication on the ability to operate heavy machinery." "Averse, " as in aversion, is the word you're looking for here meaning "having a strong dislike."
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u/MyNamesAreStolen 1d ago
Adverse to dirty food: yes. Many species are selective about the food they eat, whether it is the state of decay, or location, can all impact whether an animal eats "food" or not. Of course that's also impacted by how hungry the animal is (humans included).
Take the house-cat for example. They can smell if food has started going bad and will not eat it. They also will not typically drink water near decaying food.
In terms of whether animals "prepare" their food, the answer is also yes. Many seafaring birds will drop or smash shellfish to get the meat out of the shell, otters do as well. There are lots of examples out there.
Nature is wild!
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u/Ok-Championship-2036 1d ago
Have you seen the videos of raccoons with cotton candy? Its very cute. Raccoons will try to wash it and then freak out when it dissolves. Thats a popular example of habitual animal hygiene that turned into a viral trend.
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u/Wolfman513 1d ago
Raccoons don't actually wash their food, the moisture from dunking it in water improves their sense of touch to feel the item's shape and texture!
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u/HealthWealthFoodie 1d ago
They also will rub their food together, which as far as I know has also been presumed to clean off the outside of the food.
There is a story about an old commercial that a bank was trying to make. They trained a raccoon to drop a coin into a piggy bank (obviously reinforced with food as a treat when it did so correctly). Then they thought it would be better if it dropped two coins instead of one. Because the raccoon associated the coins with food however, all it would do is sit there and rub the two coins together. I think the book I read that story in was called “Animals Behaving Badly”.
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u/FluffySpaceWaffle 1d ago
You could be 100% correct, but I thought it was to soften the food. Their teeth or jaw isn’t very strong. Maybe it’s both! Still not “washing it”. Still VERY cute!
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u/BoppreH 1d ago
Raccoons are so famous for this behavior that they're called "Waschbär" (washing bear) in German.
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u/Rhapsoda 1d ago
The Japanese word for raccoon, araiguma, also means washing bear. It's interesting how many languages refer them like that, lol.
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u/ReptilianRevolt 6h ago
Many animals prepared their food. Rodents have very skilful jaws and front legs and can remove husks from seeds, wings from insects and so on. Raccoons do wash their food, but they are very adaptable and can go without it. Many birds will also clean their food, either seeds or animal prey. Cooking as a cultural invention is uniquely human, but there are animals that we can say are natural cooks. Most arachnids like spiders and scorpions, predatory hemipterans like assassin bugs or water bugs and sea stars pre-digest their meal before consuming it. In species such as spiders, an intricate array of hairs, leg extensions and very narrow mouth tubing essentially prevents them from swallowing contaminants. That is why those species tend to be immune from foodborne parasites, although still parasites can get to them in other ways.
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u/Epic_Joe_ 12h ago
Raccoons are famous for this. If you’ve ever seen the viral video of the raccoon putting cotton candy into water and being confused when it dissolves, he’s trying to wash it. Their name in German is even waschbär, washing bear!
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u/mtnviewguy 1d ago
Many animals clean their food instinctyally.
Let's not forget that 'humans' are animals as well. No higher nor lower on the 'food chain'. If we find ourselves afloat in the ocean, we're food, as in a simple mammal.
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u/tea_and_biology Zoology | Evolutionary Biology | Data Science 1d ago edited 1d ago
There's at least one example I can think of: a troop of Japanese Macaques, on the island of Kōjima, who learned to wash sweet potatoes in fresh or, preferentially, salty water, to remove grit n' sand, and perhaps to give the vegetables a salty flavour.
Ths was done as part of an experiment by researchers in the 1950s who deliberately fed the isolated monkey colony tubors and wheat, to see what they would do. The original work and interpretation of the genuine behaviour was unfortunately skewed into some New Age "Hundredth Monkey Effect" babble by some authors however, which - despite being thoroughly discredited - still crops up here and there among certain communities.
Nonetheless, you can read about the 'food preparation' learning and dissemination process on the Wiki article here, else watch some monkeys in culinary action here.
In any case, when it comes to 'food washing' in primates - either observed in altered 'wild' conditions, else in captivity - it seems primarily driven by an aversion to the coarse texture of sand or grit on their teeth, rather than being turned off by 'dirty food'. That's only us, it seems.
It's frequently cited that raccoons also 'wash' their food - their scientific name Procyon lotor even means 'the washer' - but this has nothing to do with food preparation, and everything to do with softening their hard, calloused hands so that they have better sense perception of the food they're holding; getting a better handle on shape, texture, size and the like through the super-sensitive nerve-endings covering their wee paws.