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evolution time.


James Dixon

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I read some research news recently that life started at a about 1 billion years. It, apparently, may have emerged quite quickly..

 

That makes sense, since life is more efficient at using energy from the sun. Once begun, it seems to have kept looking for even better ways to develop.

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considering the earth is nearly five billion years old and totally empty of any living thing then what was going on in all those billions of years before life did emerge.

What is your timeline that you are working to? When do you think life started in relation to the age of the Earth?

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considering the earth is nearly five billion years old and totally empty of any living thing then what was going on in all those billions of years before life did emerge.

 

As StringJunky points out, this is a mischaracterization of the problem.

 

What was going on during the ~billion years before life emerged? One thing is: it was cooling down. That took some time — you won't get life as we know it emerging on a planet where liquid water can't form. That took a few hundred million years.

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To add to already mentioned cooling down from its molten state and appropriate conditions developing through abiotic processes that would have accounted for much of the time, can probably add a long period of chemical evolution that was surely a precursor to the evolution of life as we loosely define it, along with the time that was required for the unlikely in the short term to become the inevitable in the long term.

 

There is a perspective that life was not inevitable, maybe even statistically unlikely, even over the time scales available, and that luck may have brought it about, in so much as you can define an unlikely event that actually occurred as luck. I wouldn't subscribe to that perspective. Deterministic processes and physics and all that...

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... I wouldn't subscribe to that perspective. Deterministic processes and physics and all that...

What increases the odds is that the behaviour of chemicals, under certain conditions, is predictable; they only need to be within reactive range of each other; that there's a healthy dose of determinism.

Edited by StringJunky
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There is a perspective that life was not inevitable, maybe even statistically unlikely, even over the time scales available, and that luck may have brought it about, in so much as you can define an unlikely event that actually occurred as luck. I wouldn't subscribe to that perspective. Deterministic processes and physics and all that...

 

You can only speculate whether life was likely to form so quickly or not, because you have only one case of life originating. That's not enough data to be making such assumptions, especially given that abiogenesis is still very poorly understood.

 

But the fact is that the oldest known banded iron formations, which were created largely with the help of photosysnthetic organisms are as much as 3.8 bya and potentially biogenic carbon was discovered in rocks 4.1 billion years old. If that's the case, life in the most primitive forms should have come to be almost instantly (by geological time scales) after Earth had attained favorable conditions.

 

If, hopefully, we do eventually find signs of life on Mars, this will be a lethal blow to "life was unlikely" idea, since on Mars conditions favorable to life would have existed only early on and only for a few hundred millions of years.

 

http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html

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You can only speculate whether life was likely to form so quickly or not, because you have only one case of life originating. That's not enough data to be making such assumptions, especially given that abiogenesis is still very poorly understood.

 

But the fact is that the oldest known banded iron formations, which were created largely with the help of photosysnthetic organisms are as much as 3.8 bya and potentially biogenic carbon was discovered in rocks 4.1 billion years old. If that's the case, life in the most primitive forms should have come to be almost instantly (by geological time scales) after Earth had attained favorable conditions.

 

If, hopefully, we do eventually find signs of life on Mars, this will be a lethal blow to "life was unlikely" idea, since on Mars conditions favorable to life would have existed only early on and only for a few hundred millions of years.

 

http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html

Yes, mars could be a game changer.

 

I hadn't heard of that finding from 4.1 billion years ago, interesting. It does seem very early, but I know there is some shift in the narrative of the early earth and its condition. It may even spark renewed interest in panspermia (although I doubt it).

 

Although caution must be urged.

 

I know a lot of people want to use such data as evidence of life, but this is governed more by what they want the outcome to be rather than scientific principles,” NASA astrobiologist Thomas McCollom tells Barras.

This skepticism in part comes from a study published in 2008 that claimed to have similarly found microscopic diamonds embedded in 4.25 billion-year-old zircon crystals. After their results were questioned, the scientists discovered the diamonds were merely contamination from grit used to polish the crystals.

While Bell and her team were careful to prevent similar issues, other researchers remain wary that graphite could have formed during the Hadean. Some suggest the graphite could have even been encapsulated at a later date by zircon melting and recrystallization.

“That one negative experience doesn’t mean nobody should try again,” California Institute of Technology geologist John Eiler tells Rosen. “But let’s just say, I’m cautious.”

While Bell and her colleagues are excited by their find, they aren’t ruling out non-biological explanations for the graphite either. In the meantime, the best support for their theory would be replication—whether it is from other graphite-containing Hadean zircons or ancient Martain life, which has rocks even older than the Earth, Rosen writes.

“Hopefully we didn’t just chance on the one freak zircon that had graphite in it,” Bell tells Rosen.

http://www.smithsonianmag.com/smart-news/did-life-really-start-41-billion-years-ago-not-so-fast-180957006/?no-ist

 

Edited by tantalus
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