Life came to Earth from comet?

[Nellisir]

What's fire got to do with it? I mean... fish?

Do you not think we'll find anything in places like the seas of Europa?

I think he's using "fire" as some kind of weird shorthand for "chemical reaction involving free oxygen", except he's also assuming that free oxygen is somehow required to unbind CO2, or perhaps that CO2 and O2 are different beasts.

 

[Nellisir]

Venus has an atmosphere similar to pre-Oxygen cataclysm Earth and thus too much CO2 thus fires are suppressed.

You're going to have to explain this one a bit.

First of all, what's an "Oxygen Cataclysm"?
Second of all, are you talking about fire as in burning firewood, or fire as in "chemical reaction involving oxygen, like rusting and tarnishing"?
Third, if you took Venus's atmosphere, cooled it down, and seeded it with plant life, the plants would absorb the CO2 and release O2. Yes or no?

 

[Umbran]

First of all, what's an "Oxygen Cataclysm"?

I think he's referring to what is elsewhere called the "Great Oxygenation Event", the "Oxygen Catastrophe" or the "Oxygen Crisis" - the original appearance of significant amounts of free oxygen in our atmosphere.

Note that, in all likelihood, early procaryotic and eucaryotic organisms carrying out photosynthesis predate the O2 building up in the atmosphere. To start with, a lot of the O2 they created would have immediately bound up with iron and other minerals. Only after much of the stuff free on the surface had oxidized would O2 start to accumulate in the air.

 

[Kramodlog]

What's fire got to do with it? I mean... fish?

Do you not think we'll find anything in places like the seas of Europa?

I think he means fire is what help our ancestors evolve into us. Cooking helped us cook meat, giving more energy to the brain, reducing our mastication time, harded wood, scare off beats, etc.

He does have a point too. No other animal produces fire artificially. Some point to tools or language has what differenciates us from other animals, but tools and communication do exist in other animals, even if very primitive. Fire does not.

Not sure what this has to do with comets or life in general.

 

[Nellisir]

I think he means fire is what help our ancestors evolve into us. Cooking helped us cook meat, giving more energy to the brain, reducing our mastication time, harded wood, scare off beats, etc.

Yeah, but he said this:

Yeah I do have a broader definition of fire being any exothermic redox reactions including respiration, fire, fermentation, corrosion, digestion etc. Some archaea did utilise dissolved oxygen compounds prior to the GOE but regardless I'd argue that complex life requires the levels of oxygen present on Earth, which is rare.

so I think he just means a lot of free oxygen.

In any other environment be would be stuck with archaea or viruses...

I skipped over this before, but I fail to see the problem. Is the OP that life must be identical to life here? Why is anaerobic life automatically disqualified?

He does have a point too. No other animal produces fire artificially. Some point to tools or language has what differenciates us from other animals, but tools and communication do exist in other animals, even if very primitive. Fire does not.

True, but that seems like a weirdly fuzzy criteria. I mean, we have had fire for possibly a half a million years. Fire use predates modern humans. Fire doesn't seem to lead to civilization (if it does its the slowest path ever...). The native american civilizations did pretty well without much metalworking, so if you've got a lifeform that doesn't need to cook food (which most don't), they could probably easily reach medieval levels of civilization without fire. It gets useful for chemistry after that, so who knows? On a cold world "fire" might mean melting water.

 

[Kramodlog]

It does seem to lead to intelligent life, but I agree this is anthrocentric. We have very little else to work with aside from speculation.

 

[Nellisir]

It does seem to lead to intelligent life, but I agree this is anthrocentric. We have very little else to work with aside from speculation.

Fire or oxygen? I don't see fire "leading" to "intelligent" life; we had it before we were homo sapiens sapiens, but we were still homo/human.

I think the more important factors are community and communication. With radical exceptions, a civilization is going to be a group of creatures that works together and can propagate learned information beyond themselves. Tigers could be really really smart, but they're never going to hang out and be sociable together.

I would also hypothesize that higher intelligence is more likely to arise in creatures that are flexible in diet and habitat and not apex predators, although they might be nearer the top than the bottom. Specialized diets lead to hardwired behavior, not learned behavior. IMO.

 

[Kramodlog]

Fire or oxygen? I don't see fire "leading" to "intelligent" life; we had it before we were homo sapiens sapiens, but we were still homo/human.

Fire.

Homo is the genus. Humans are homo, but not all homos are human. Umm... The latin thing, not folks who like same sex folk.

Did fire help us become homo sapiens sapiens instead of just being very intellegient apes? In theory it helped. More energy for the brain by cooking meat, reducing mastication time by cooking food so we have more time to do other stuff, perfect tools, etc.

I think the more important factors are community and communication. With radical exceptions, a civilization is going to be a group of creatures that works together and can propagate learned information beyond themselves. Tigers could be really really smart, but they're never going to hang out and be sociable together.

Other animals have communities and communication. Ants, canines, other primates. None have fire. It really is a human thing.

Of course corellation doesn't mean causation.

 

[Nellisir]

Homo is the genus. Humans are homo, but not all homos are human. Umm... The latin thing, not folks who like same sex folk.

Right. According the all-knowing wikipedia, which was all I had time to look at tonight, fire-use goes back somewhere between 200,000 and 1.2 million years, with 400K being pretty solid right now. 200K would put it out of H. sapiens, and into very late H. erectus. I forget where things are with neandertals; I think there's evidence for fire-use there. 1.2 million puts it way back into solid H. erectus; no neandertals, no sapiens.

Other animals have communities and communication. Ants, canines, other primates. None have fire. It really is a human thing.
Of course corellation doesn't mean causation.

Right, exactly. Is fire-use causation of humanity, or consequence? Is it a tool, or more than a tool? Ants don't have radio either, but not many people would argue radio is our defining feature - it's a tool we use.

I'm not saying anything with communication and socialization is a civilization; I'm saying a civilization has to have communication and socialization. So not all human-level intelligences are going to form civilizations, because not all of them will a) communicate and b) socialize.

The weird exemption may be AIs. Above a certain point, I fail to see what would keep two AIs from becoming one (it's all just code, and given sufficient processing power and storage, you can run all the code you want), at which point you might well end up with something that could reasonably be called a solar mono-intelligence, and mimic a civilization.

 

[Umbran]

I skipped over this before, but I fail to see the problem. Is the OP that life must be identical to life here? Why is anaerobic life automatically disqualified?

I don't have a direct link to documentation, but by my memory it has to do with energy the metabolic system can provide - this is limited by the laws of chemistry. Things like big brains require significant levels of both energy and power (power in the scientific sense - energy per unit time), and metabolic systems that cannot provide those are, if not out of the running, at least at a significant disadvantage.