barbos
Contributor
No it does not. Geologic record shows that life emerged pretty much instantly.
As I said "once you managed to multicellular stage."
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Revisiting the Drake Equation
- Thread starter lpetrich
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barbos
Contributor
They would, but it would be very rare occurrence .
barbos
Contributor
https://en.wikipedia.org/wiki/RNA_world was is well supported and recent papers claim origin of life has been solved.
lpetrich
Contributor
I agree that that's a big unknown.
The earliest metazoans : Nature The earliest known animals are sponges in the class Demospongiae, identified from some of their chemical constituents: 24-isopropylcholestanes in rocks over 635 million years old. The earliest possibly-animal body fossils are about 600 Mya (Ediacaran biota from Sonora, Mexico.).
The 1200-Mya red alga Bangiomorpha pubescens is the oldest undoubted multicellular eukaryote.
Cyanobacteria have several multicellular species, and their multicellularity originated some 2500 Mya.
Evolution of multicellularity coincided with increased diversification of cyanobacteria and the Great Oxidation Event
Cyanobacteria and the Great Oxidation Event: evidence from genes and fossils
There are some other multicellular prokaryotes. Actinobacteria include some species that make fungus-like mats of strands (mycelia), and myxobacteria act like slime molds. Myxobacteria are delta-proteobacteria, while actinobacteria are in the recently-recognized taxon Terrabacteria. This group also includes cyanobacteria, Firmicutes (thick-skinned sporeformers), and Deinococcus-Thermus. Deinococcus radiodurans is known for surviving ionizing-radiation doses that would kill most other organisms, like 1000 times the human lethal dose. This is a side effect for surviving dryness, something that makes similar damage to its genome.
From A genomic timescale of prokaryote evolution: insights into the origin of methanogenesis, phototrophy, and the colonization of land | BMC Evolutionary Biology | Full Text, the Terrabacteria likely emerged some 3 billion years ago. So actinobacterial multicellularity may go back almost that far, much like cyanobacterial multicellularity.
lpetrich
Contributor
I agree that the RNA world is well-supported, but it's still some way from the origin of life. It's hard to make ribose prebiotically, for instance.
That I'd like to see.
barbos
Contributor
I saw it in the news couple of weeks ago. They claimed they solved all remaining questions of RNA world hypothesis. Simple life is unavoidable.
James Brown
Veteran Member
Sure. Each step in the Drake Equation is more rare than the one preceding it.
But in an infinite universe, even extremely rare probabilities occur frequently, don't they?
lpetrich
Contributor
That I'll have to see. I'll also have to check on whether this is a case of the game "Telephone".
barbos
Contributor
parameters in the Drake Equation are relative probabilities, not absolute.
barbos
Contributor
--
It was several hundred million years from multi-cellular life to intelligence. That doesn't make it a foregone conclusion.
Infinite universe?
The only way we could possibly have an infinite universe is if sufficiently distant parts of it are receding at above lightspeed. Otherwise you're facing Olber's Paradox.
Don2 (Don1 Revised)
Contributor
on average?
barbos
Contributor
It does, virtually all complex organisms were developing some kind of intelligence independently. Birds, mammals, sea creatures.
??
Look up Olber's Paradox if you don't understand why there can't be an infinite, visible universe.
Don2 (Don1 Revised)
Contributor
I was asking about if that was "on average" and I do understand Olbers Paradox and I had looked it up.
I'll take my first question as unanswered. Second question:
What about black holes?
Suppose the universe is sufficiently dense with black holes, planets, exo-planets, gas, and dust. Does this work against the proposition that we'd see tremendous light if sufficiently distant parts of the universe were not receding at above light speed?
Also, I think you've perhaps misunderstood Olbers Paradox. Olbers Paradox assumes A, B, and C, and then demonstrates all cannot be true. One of them is infinite age of the Universe and another is infinite extent. Perhaps it could still be possible to have an infinitely extending universe but not an infinite age. Maybe?
Feel free to answer any or all of my 3 questions.
I'll take my first question as unanswered. Second question:
What about black holes?
Suppose the universe is sufficiently dense with black holes, planets, exo-planets, gas, and dust. Does this work against the proposition that we'd see tremendous light if sufficiently distant parts of the universe were not receding at above light speed?
Also, I think you've perhaps misunderstood Olbers Paradox. Olbers Paradox assumes A, B, and C, and then demonstrates all cannot be true. One of them is infinite age of the Universe and another is infinite extent. Perhaps it could still be possible to have an infinitely extending universe but not an infinite age. Maybe?
Feel free to answer any or all of my 3 questions.
Planets, gas and dust do nothing about Olber's paradox--they'll absorb the energy falling on them and heat up until they're just as bright. Only black holes can sink the energy--and for them to matter the vast majority of spots in the sky must actually be a black hole event horizon. They would have to be by far the dominant mass in the universe because they're so much smaller than stars.
Don2 (Don1 Revised)
Contributor
Does this finding impact any estimates of variables? Not at all? Are things still just as unclear?
https://www.cnet.com/news/oldest-fossils-alien-life-earth-universe-western-australia-schopf/
https://www.cnet.com/news/oldest-fossils-alien-life-earth-universe-western-australia-schopf/
barbos
Contributor
It confirms my estimates. I said that simple life probability is 100% (given suitable conditions like liquid water)