Let's create an alien biosphere!

[MathAndCode]

What do you think we should work on now then? I say we should keep talking about multicellular organisms.

I think that we should discuss some of the other developments that will occur in the explosion of diversity. They could make multicellular life more or less likely to arise.

[Schiaparelliorbust]

I think that we should discuss some of the other developments that will occur in the explosion of diversity. They could make multicellular life more or less likely to arise.

Life could start using chemical signals to communicate. I can't really think of any useful messages other than "danger" and perhaps "food". Can you? Also, organisms might also start making deceptive messages, e.g. sending a danger signal to make others eating food you want to go away.

[MathAndCode]

Life could start using chemical signals to communicate. I can't really think of any useful messages other than "danger" and perhaps "food". Can you? Also, organisms might also start making deceptive messages, e.g. sending a danger signal to make others eating food you want to go away.

That would be more likely with a higher population density, but there is no reason for it to happen unless the organism sending the message and the organism receiving the message each benefit.
Perhaps mobile organisms could learn to interpret an increased concentration of reactive oxygen species in the water as a sign that danger is near and swim away from them?

[Schiaparelliorbust]

That would be more likely with a higher population density, but there is no reason for it to happen unless the organism sending the message and the organism receiving the message each benefit.
Perhaps mobile organisms could learn to interpret an increased concentration of reactive oxygen species in the water as a sign that danger is near and swim away from them?

Wouldn't more biodiversity imply higher population densities? I think that if any organism evolves a two-way signalling system, it would proabably be more succesful, too. I would also think that any organism that doesn't flee higher concentrations of harmful subsatnces would be greatly selected against. Maybe as a danger signal they could repurpose non-harmful but detectable amounts of reactive oxygen species.

[MathAndCode]

Wouldn't more biodiversity imply higher population densities?

I suppose so to a certain extent, but higher population densities wouldn't imply biodiversity, although they would likely lead to it because increased competition would likely drive specialization.

I think that if any organism evolves a two-way signalling system, it would proabably be more succesful, too.

Yes, but there can't be an evolutionary pressure for the receiver to evolve a signal reception mechanism until the sender has evolved a signal emission mechanism, and vice versa.

I would also think that any organism that doesn't flee higher concentrations of harmful subsatnces would be greatly selected against. Maybe as a danger signal they could repurpose non-harmful but detectable amounts of reactive oxygen species.

Keep in mind that the only reason that they would detect reactive oxygen species is that prey organisms would release them when a predator approaches in order to ward the predator off, and also this wouldn't happen yet because predation hasn't arisen yet. It likely will develop soon due to the increase density of potential prey, though.

[Schiaparelliorbust]

Yes, but there can't be an evolutionary pressure for the receiver to evolve a signal reception mechanism until the sender has evolved a signal emission mechanism, and vice versa.

Keep in mind that the only reason that they would detect reactive oxygen species is that prey organisms would release them when a predator approaches in order to ward the predator off, and also this wouldn't happen yet because predation hasn't arisen yet. It likely will develop soon due to the increase density of potential prey, though.

Let's find a way of making our decisions official. I never thought we had completely agreed on predation, but I still thought we had it a bit.
I think that any prey would have a way of at least detecting reactive oxygen species so what they excrete doesn't kill them. They might evolve resistance or they might just flee the area. Wouldn't reactive oxygen species just kill predators instead of simply deterring them?

[MathAndCode]

I think that any prey would have a way of at least detecting reactive oxygen species so what they excrete doesn't kill them. They might evolve resistance or they might just flee the area.

They already need resistance to reactive oxygen species because they produce them during photosynthesis—although the predator may as well if it has an electron transport chain.

Wouldn't reactive oxygen species just kill predators instead of simply deterring them?

That would also save the prey.

[Schiaparelliorbust]

They already need resistance to reactive oxygen species because they produce them during photosynthesis—although the predator may as well if it has an electron transport chain.

They would definitely have some resistance because they (both predator and prey) originated from the same group (I think), but the secretion of reactive oxygen species would still be useful because it would be in higher quantities. Would there be organisms that still don't have the electron transport chain?

[MathAndCode]

They would definitely have some resistance because they (both predator and prey) originated from the same group (I think).

Yes, but that was before they developed photosynthesis or an electron transport chain.

Would there be organisms that still don't have the electron transport chain?

Yes. None of the organisms upcurrent or downcurrent of the hydrothermal vents have electron transport chains, and not all of the organisms at the hydrothermal vents have electron transport chains.

[Schiaparelliorbust]

Yes, but that was before they developed photosynthesis or an electron transport chain.

Yes. None of the organisms upcurrent or downcurrent of the hydrothermal vents have electron transport chains, and not all of the organisms at the hydrothermal vents have electron transport chains.

From your timeline post, this is the only group of organisms that develop an electron transport chain.

209 million years after the planet's formation: Polysulfate-building organisms develop an electron transport chain, which they use for the reaction SO₄²⁻+10H⁺+8e⁻→H₂S+4H₂O, using the energy to attach other free sulfate to sulfate chains.

[MathAndCode]

From your timeline post, this is the only group of organisms that develop an electron transport chain.

209 million years after the planet's formation: Polysulfate-building organisms develop an electron transport chain, which they use for the reaction SO₄²⁻+10H⁺+8e⁻→H₂S+4H₂O, using the energy to attach other free sulfate to sulfate chains.

Yes. I checked with the timeline before posting.

[Schiaparelliorbust]

Yes. I checked with the timeline before posting.

Would one group have a more high-energy lifestyle? If so, they might become more successful predators.

[MathAndCode]

Would one group have a more high-energy lifestyle? If so, they might become more successful predators.

The organisms with the electron transport chain would likely be able to live a higher-energy lifestyle.

[Schiaparelliorbust]

The organisms with the electron transport chain would likely be able to live a higher-energy lifestyle.

So should we create predation now then?

[MathAndCode]

So should we create predation now then?

We should create scavengers first (or have we already finalized those?). Once that is done, we can create predators.



Edit: Actually, we should figure out what the potential food sources will be first.

[Schiaparelliorbust]

We should create scavengers first (or have we already finalized those?). Once that is done, we can create predators.



Edit: Actually, we should figure out what the potential food sources will be first.

Scavengers could start out with already abiotically decayed biomass with simpler molecules and then try and get higher-quality food from recently deceased cells.

[MathAndCode]

Scavengers could start out with already abiotically decayed biomass with simpler molecules and then try and get higher-quality food from recently deceased cells.

That's a good idea especially because of evolution. Which molecules would they seek out?

[Schiaparelliorbust]

That's a good idea especially because of evolution. Which molecules would they seek out?

They could start with methane, ethane and other simple organic compounds and then would then try to eat longer molecules. Do these organisms use polymers at all?

[MathAndCode]

They could start with methane, ethane and other simple organic compounds and then would then try to eat longer molecules. Do these organisms use polymers at all?

Yes, we can assume that they use polymers for information storage and structural support.

[Schiaparelliorbust]

Yes, we can assume that they use polymers for information storage and structural support.

What type of polymers might they be? Alkanes are the simplest, or they could maybe chain many monomers (like sugars) together.

[MathAndCode]

What type of polymers might they be? Alkanes are the simplest, or they could maybe chain many monomers (like sugars) together.

There are a variety of possibilities, but I think that it's best to stick with the biomolecules that our cells use except for replacing phosphate with sulfate and either replacing proteins or using a different set of R groups.

[Schiaparelliorbust]

There are a variety of possibilities, but I think that it's best to stick with the biomolecules that our cells use except for replacing phosphate with sulfate and either replacing proteins or using a different set of R groups.

About 500 naturally occurring amino acids are known as of 1983 (though only 20 appear in the genetic code) and can be classified in many ways.

Are the 20 amino acids life on Earth use used for a reason or are they random?

[MathAndCode]

Are the 20 amino acids life on Earth use used for a reason or are they random?

They are random.

[Schiaparelliorbust]

They are random.

So I guess which ones we choose or how many won't matter much.

[MathAndCode]

So I guess which ones we choose or how many won't matter much.

That's correct.