What is the purpose of yeast in nature?

Yeast have been used to produce CO2 and alcohol for thousands of years, but what is their purpose in ecology?

decomposition of organic matter?

Why do they have to have a purpose? They have an abundant food supply and are very resilient and adaptive. They don't have to do anything, they just have to be good at what they do.

Evolution does not dictate that everything have a specific purpose.

They are useful in making bread and beer (so we cultivate them, which is good for their species) and in balancing out sugars in other organisms (like people), so they have a symbiotic relationship with other living things. But if we could ask them, they would probably say they have the same purpose as us all--propogation of the species.

Well giving you my non-expert opinion since I'm not an ecologist:

Some strains can be parasitical (yeast infections), some can be symbiotic (in your digestive system).

They protect their turf by creating toxins such as alcohol and sulfites, and influencing acidity, impeding the development of other organisms in whatever medium they are fermenting.

Animals enjoy fermented materials, providing an additional inducement (beyond the sugar) to eat fruits and poop out the seeds somewhere, ensuring propagation of the plant species.

All those things you just listed are by products of species propagation and evolution. Natural selection determined where yeast live, what they eat, and who they benefit. Yeast as a species had no say in the matter.

This is probably one of the best questions ever asked on here. I've honestly never given it a thought, but wow....

From WikiPedia:

The ecological function and biodiversity of yeasts are relatively unknown compared to those of other microorganisms.

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An interesting read.

The only purpose of any living thing is to reproduce and perpetuate the species.

Yeasts are a simple, single celled eukariotic fungi. They are decomposers, which accounts for their worldwide prevalence and distribution. We just benefit from their waste byproducts.

Agreed, this is a really good question to ask. Assuming you're talking specifically about S. cerevisiae (as opposed to yeast/fungi in general), I think the theory is they evolved to live off of tree saps and fruit, which of course are very rich in sugar.

to survive, like Passedpawn said.

PupThePup said:

Yeast have been used to produce CO2 and alcohol for thousands of years, but what is their purpose in ecology?

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GMesick said:

They are useful in making bread and beer (so we cultivate them, which is good for their species) and in balancing out sugars in other organisms (like people), so they have a symbiotic relationship with other living things. But if we could ask them, they would probably say they have the same purpose as us all--propogation of the species.

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Revvy said:

This is probably one of the best questions ever asked on here. I've honestly never given it a thought, but wow....

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passedpawn said:

The only purpose of any living thing is to reproduce and perpetuate the species.

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Agree with all of this, species perpetuation primarily.

aiptasia said:

Yeasts are a simple, single celled eukariotic fungi. They are decomposers, which accounts for their worldwide prevalence and distribution. We just benefit from their waste byproducts.

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Don't you find it odd that we benefit from their waste products? Similarly, Honey is regurgitated by Bees, Mold is used to flavor and enhance cheese - some of the most flavorful and enjoyable substances on earth are derived by the fermentation and/or breakdown of other substances using yeasts, molds and bacterias.

There are exponentially more species who's waste products we don't benefit from. Similarly there are plenty of other species that benefit from our waste products. That's the beauty of natural selection. Eventually everything that survives will form a nice "circle of life".

they produce alcohol, which helps humans reproduce and perpetuate the species

dinnerstick said:

they produce alcohol, which helps humans reproduce and perpetuate the species

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Very good

dinnerstick said:

they produce alcohol, which helps humans reproduce and perpetuate the species

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Best answer yet!

dinnerstick said:

they produce alcohol, which helps humans reproduce and perpetuate the species

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That's friggen awesome!

Rick

dinnerstick said:

they produce alcohol, which helps humans reproduce and perpetuate the species

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Now that we've reached consensus, maybe someone should update Wikipedia???

passedpawn said:

The only purpose of any living thing is to reproduce and perpetuate the species.

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In a nutshell, yeah. Not to get all existential on you, but what is the purpose of mankind?
To slay and destroy?

If making beer is our only purpose, than may we do so with great earnest.

passedpawn said:

The only purpose of any living thing is to reproduce and perpetuate the species.

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Exactly.
Everything has adapted to find a niche where they can survive. Survival is the purpose.
The fact that the existence of a species and it's impact on the world around them helps another plant or animal is simply because all life has been adapting since time began and no opportunity has been left without something taking advantage of it.

I saw something on discovery the other day about a cave in one of the driest places on the earth.
The cave is accessed through what is essentially a crack in the ground.
Inside the cave is the largest underground lake in the world.
Inside this lake are blind catfish that have adapted to need very little oxygen and their only food source is bat crap.

Now I ask you, what purpose do they serve other than the purpose of survival?
These and decentness of normal catfish that swam around at a time when there was water above the opening to the cave. As the water went away, the fish were trapped and they did what the ancestors of every living thing on the earth has done. They adapted to the new situation and survived.
That is what life is.

It's entirely possible that every living thing does have a purpose, but the complexity of the entire system is such that it may never be known.

pelipen said:

It's entirely possible that every living thing does have a purpose, but the complexity of the entire system is such that it may never be known.

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As a species, or individually?
Because I know some people who seem to defy the theory of having a purpose.

Survival in and of itself as a purpose of an organism or species.

I’m not sure that I can agree with that. It does seem that the ability of a species to survive is more of a quality measurement of something else that “may” be of a higher level purpose. For example, perhaps the purpose of yeast is to help facilitate some kind equilibrium for a broader ecosystem. As someone earlier pointed out, and I paraphrase, to help “some” of us in the human species to procreate. Or at least to help us have the opportunity of trying. I suspect that yeast does not self-reflect and ask about the purpose of its existence. But, I can’t be sure of that I’ve heard it said that asking that question about purpose is perhaps one of the more significant things that make us human. But it’s my hunch that the purpose of any organism is not individual in nature, but collective with respect to a larger ecosystem or universe. Purpose it is time for a beer for more contemplation…

You guys sound like a bunch of yeast atheists. What about yeast heaven and the yeast afterlife? Maybe yeast exist in nature to achieve a state of perfect fermentation?

dinnerstick said:

they produce alcohol, which helps humans reproduce and perpetuate the species

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Who in turn cultivate more and stronger yeast. Talk about a symbiotic relationship!

45_70sharps said:

As a species, or individually?
Because I know some people who seem to defy the theory of having a purpose.

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Fortunately they usually get a posthumous Darwin Award.

jaw94087 said:

For example, perhaps the purpose of yeast is to help facilitate some kind equilibrium for a broader ecosystem.

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You can't separate the ecosystem from its contents. The universe is not a static place. It sometimes appears that way, but that's because our lifetimes (and all of humanity) sample such a miniscule fraction of history. The current state of earth and its ecosystems has only been in place for the briefest flash, and for all we know it's a very temporary state of affairs.

Yeast, like any organism, is a part of an ecosystem. Members of it live and die because they happen to interact in particular ways. We're a part of this as well, so it's a perfectly valid observation that human eating and drinking habits are a bit part of the reason that yeast are doing so well.

It is sort of strange when you realize how tightly interwoven we are with other organisms in the environment. But it's not a coincidence or miracle that yeasts and molds happen to produce compounds that we can consume. Part of the reason that our human biology uses those compounds to produce energy is that they were available in the environment. We produce waste of our own, and organisms that can make a living decomposing that crop up. The links continue and eventually you get back to where you started and *poof*, you have a food chain. But it's not stable---entropy is increasing, energy stores in the system are being depleted, and eventually a piece dies out and it's no longer circular. Things fall apart for a while until a new cycle is found, probably with many pieces similar to the previous equilibrium, but never quite the same....

Nature seems to like equilibria simply because they're, by definition, stable.

DonLiguori said:

In a nutshell, yeah. Not to get all existential on you, but what is the purpose of mankind?
To slay and destroy?

If making beer is our only purpose, than may we do so with great earnest.

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Their greatest coup was making yummy beer.

We then perpetuate the yeast, going to outrageous ends to make the perfect growing environment for it, saving it, making more and more yeast. Then spending countless dollars and time to make more wort and beer to perpetuate the yeast.

The yeast exist to enslave us. It is their greatest ability.

mcbaumannerb said:

Who in turn cultivate more and stronger yeast. Talk about a symbiotic relationship!

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Agreed. And by evolving into strains that allow us to produce delicious beers, they have ensured their survival.

What does this mean? Yeast have domesticated us people.

Grantman1 said:

Agreed. And by evolving into strains that allow us to produce delicious beers, they have ensured their survival.

What does this mean? Yeast have domesticated us people.

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You could probably say (some) yeast depends on us for existence. I once read that we have cultivated corn to the point where it's no longer capable of seeding itself like grass, and would die out if we didn't replant it.

I suspect if we didn't meddle, everything would have an FG around 1.000.

Subsailor said:

Agree with all of this, species perpetuation primarily.



Don't you find it odd that we benefit from their waste products? Similarly, Honey is regurgitated by Bees, Mold is used to flavor and enhance cheese - some of the most flavorful and enjoyable substances on earth are derived by the fermentation and/or breakdown of other substances using yeasts, molds and bacterias.

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And let's not forget where mushrooms grow....

So, is it coencidental that hops are bacteria free and a natural perservitive? I think everything has a pupose and if it does not then we just have not figured it out yet.

I love the quote listed below!

"beer is living proof that God loves us and wants us to be happy" Franklin

So, let's all go get happy

No purpose other than that of any other life form (you for instance), to grow feed and propagate to species. Man has just learned to tame them for our purposes like other life forms, i.e cattle, corn, grain, fish etc.

Same as you and I. Take up time and space. It's our task to make the world better with it. And we know how to do that!

sjohnv3 said:

So, is it coencidental that hops are bacteria free and a natural perservitive?

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No, it's not coincidental, but it doesn't have to be deep.

Hops are antibacterial for their own sake. Many plants have this property. Hops happen to be edible and have a pleasant (or at least acquirable) taste and bitterness that can balance sweetness. That is why they are used in beer. The reason we associate them with beer so strongly is simply that they've been used in that context for a couple dozen generations.

Before that, one would have mused about how miraculous it was that heather had such a nice flavor to pair with malted barley, but it was just a shame it didn't keep so well.