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Why are Yeast "vegetarian"?

Rhea

Rhea

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Why are Yeast "vegetarian"? Aren't they really little teeny animals?
 
Because the specific chemicals that they metabolize are common in plants and uncommon in animals. Plants are made up of sugars, or complex carbohydrates, while animals are made up of proteins. The only thing animals produce that is sugary enough for yeast to feast upon is milk, and only when the lactose is broken down through some means, and honey. Yeast don't have the molecular toolkit to metabolize proteins.

You learn a lot about yeast from homebrewing. There are some recipes that call for a chicken carcass, but I think that's just for flavor.
 
Underseer said:
http://en.wikipedia.org/wiki/Yeast

Technically, they're fungi. Although Fungi are a separate kingdom from plants, people generally include fungi in the "vegetarian" category when one talks about diet.
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Is that because their proteins are more plant-like than animal-like?
And I did not know yeast were fungi. Interesting. I always thought they were more bacteria-like. And those are animals, aren't they?
 
Oh, you mean vegetarians eating the yeast, rather than the yeast themselves. Fuck if I understand vegetarians.
 
Sarpedon said:
Because the specific chemicals that they metabolize are common in plants and uncommon in animals. Plants are made up of sugars, or complex carbohydrates, while animals are made up of proteins. The only thing animals produce that is sugary enough for yeast to feast upon is milk, and only when the lactose is broken down through some means, and honey. Yeast don't have the molecular toolkit to metabolize proteins.

You learn a lot about yeast from homebrewing. There are some recipes that call for a chicken carcass, but I think that's just for flavor.
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Tell me what you mean by "chemicals they metabolize". I thought that meant the things we ingest and can convert to energy - and I thought the nature of the organism would be more formed by the proteins that it _makes_ rather than the food it eats.

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Sarpedon said:
Oh, you mean vegetarians eating the yeast, rather than the yeast themselves. Fuck if I understand vegetarians.
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LOL, yeah, that's a funny exposure of my imprecision.
Yeah, I mean why are they okay in a vegetarian diet. I.e. why are they not animals.
 
Rhea said:
Is that because their proteins are more plant-like than animal-like?
And I did not know yeast were fungi. Interesting. I always thought they were more bacteria-like. And those are animals, aren't they?
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Beats the hell out of me, although I have to imagine that the lack of photosynthesis is part of it. For all I know, biologists tell the difference between plant cells and fungus cells through divination or possibly Ouija boards.
 
Sarpedon said:
Oh, you mean vegetarians eating the yeast, rather than the yeast themselves. Fuck if I understand vegetarians.
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No, I mean the vegetarians can't see the yeasts' faces. They don't like to eat faces.

edit: haha, I thought you were responding to me.
 
Perhaps its because they have cell walls, like plants and fungi, rather than just the cell membrane, like animals.

Don't ask me why they are considered to be single celled fungi instead of protazoans.

I thought the five kingdom system was obsolete anyway, in favor of the eukaryotes, bacteria, and archaea.

In other news, I am considering cutting mammals out of my diet.
 
mammals because of tick-bourne virus leading to intolerance? Or class solidarity?
 
class solidarity, that's funny.

More the growing evidence that the similarity in brain anatomy means similarity in emotional and cognitive natures.
 
Rhea said:
Is that because their proteins are more plant-like than animal-like?
And I did not know yeast were fungi. Interesting. I always thought they were more bacteria-like. And those are animals, aren't they?
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The thing you need to keep in mind is that the conventions and principles of taxonomy have repeatedly changed while English was evolving. Terminology among chefs, food Nazis, and such folk doesn't track terminology among biologists. The term "vegetarian" arose back when scientists classified the world into "animal, vegetable or mineral". Fungi were considered plants because they were alive but they weren't animals; and they weren't considered animals, basically, because they didn't have eyes, limbs, muscles, nerves, and so forth. For a long time even sponges were considered plants. Classification was based on scientists deciding which features were more important than others, so it was pretty subjective.

Since then, biology has switched to classification based on how recently organisms have a common ancestor. So the quick answer to why fungi aren't considered plants is because they're more closely related to animals. But the basic criterion for whether an X is a Y in modern taxonomy is to associate a particular organism, call it Y0, with each named category Y. Then an X is a Y if and only if Y0 is an ancestor of X. The reason fungi are not considered animals is because for animals Y0 is the sponge. You, I, and mosquitos evolved from sponges; yeast didn't.
 
Here's one of the best premodern classifications of animals, by Aristotle
  • Blooded animals
    • Live-bearing four-legged animals
    • Birds
    • Egg-laying four-legged animals
    • Fish
    • Cetaceans: dolphins and whales
  • Bloodless animals
    • Cephalopods
    • Aquatic arthropods
    • Land arthropods
    • Shelled animals
    • Zoophytes ("animal-plants" or "plant-animals")
So Aristotle recognized plantlike animals like sea anemones.

Though yeast and other fungi have animallike metabolism, they have plantlike behavior, and that's what makes the difference.
 
Sarpedon said:
class solidarity, that's funny.

More the growing evidence that the similarity in brain anatomy means similarity in emotional and cognitive natures.
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That's what I meant by "class" in the taxonomic sense. :) Makes sense, I can respect that. My reasons for beginning to lean more Vegan are more related to health and what it appears animal products do to our organs. I don't have a particularly strong aversion to killing my food as long as it is humanely done - grew up on a farm. And I don't have much embrace of cultural taboos, so I'm not averse to eating horses or cats if they are served to me. I'm one of those people who, if shipwrecked, would probably be okay eating the remains of those who didn't survive in order to stay alive, though I doubt I could kill someone in a you-or-me starvation scenario; I'd probably let us both starve rather than murder them. Still, I'd like to avoid heart disease by tending vegan in my future and at least severely limiting the percent of my food that comes from animals. :)

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Bomb#20 said:
The thing you need to keep in mind is that the conventions and principles of taxonomy have repeatedly changed while English was evolving. Terminology among chefs, food Nazis, and such folk doesn't track terminology among biologists. The term "vegetarian" arose back when scientists classified the world into "animal, vegetable or mineral". Fungi were considered plants because they were alive but they weren't animals; and they weren't considered animals, basically, because they didn't have eyes, limbs, muscles, nerves, and so forth. For a long time even sponges were considered plants. Classification was based on scientists deciding which features were more important than others, so it was pretty subjective.

Since then, biology has switched to classification based on how recently organisms have a common ancestor. So the quick answer to why fungi aren't considered plants is because they're more closely related to animals. But the basic criterion for whether an X is a Y in modern taxonomy is to associate a particular organism, call it Y0, with each named category Y. Then an X is a Y if and only if Y0 is an ancestor of X. The reason fungi are not considered animals is because for animals Y0 is the sponge. You, I, and mosquitos evolved from sponges; yeast didn't.
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Thanks. I do follow evolution so I'm familiar with most of that, but you put it very succinctly, so thanks, that provides me with good "language" to sort this in my head. I'm enjoying learning about the details of further back on the branches of evolution than I had previously cared to detail - all because of a jar of Marmite. :)
 
Rhea said:
I don't have a particularly strong aversion to killing my food as long as it is humanely done - grew up on a farm.
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Wouldn't that mean you're trending Vegetarian? Vegetarian's about the diet, Vegan's about the morals. At least, as i understand the terms. (More to the point, as i've understood them since the night i wore a leather belt to what turned out to be an evening of Vegan Poetry readings.)
 
I would not say that vegetarian is about the diet but vegan is about the morals. You can be a moral vegetarian while not embracing the slightly deranged morality of the vegans. Who object to stealing honey from bees, but ignore all the insects that get killed in even the gentlest sorts of agriculture.
 
Sarpedon said:
I would not say that vegetarian is about the diet but vegan is about the morals. You can be a moral vegetarian while not embracing the slightly deranged morality of the vegans. Who object to stealing honey from bees, but ignore all the insects that get killed in even the gentlest sorts of agriculture.
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But vegetarian may or not be due to or adopted as a moral stance about killing (some or all) animals. But vegan IS chosen because of moral positions taken.
My dad enjoys teasing relatives that announce they've gone vegan. He always says his doctor advises him to cut down on meat, too.
 
Keith&Co. said:
Wouldn't that mean you're trending Vegetarian? Vegetarian's about the diet, Vegan's about the morals. At least, as i understand the terms. (More to the point, as i've understood them since the night i wore a leather belt to what turned out to be an evening of Vegan Poetry readings.)
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No, instead it is vegetarian is not killing stuff, hence no meat; vegan is no animal products of any kind. As far as I know. It's two different diets. You can be vegetarian and eat cheese. But Vegans do not eat cheese, milk, eggs or any product that came from an animal.

So I'm beginning to reduce the dairy products and eggs as well as the meat.

although it sounds like some vegans wouldn't have me, since I still wear leather with no concern, and burn fat in candles. I just am trying to eat less of it.
 
Although yeast isn't in the plant kingdom (or technically the three kingdoms that have chloroplasts one of which includes plants) yeast isn't in the animal kingdom. The presence or absence of an organism with regards to the animal kingdom is basically the defining trait for those who call themselves vegetarians.

Technically, since their diet goes beyond the plant kingdom they should have a different term for there paraphyletic diet, but it is simpler to say "vegetarian".
 
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