New paper suggests life arrived from elsewhere (rather a long time ago)!

[Subsymbolic]

Just read this. While it's quite convincing evidence that life developed off world, I'm unsure that the conclusion of the paper, that life is common across the universe, is warranted.

https://www.sciencedaily.com/releases/2017/12/171218154925.htm

A theory that has been gaining credence over the last few years involves low temperature development of the prebiotic basis for life, even life, in comets, where the freezing action effectively reduces the water in the equation and drives surprisingly fast processes at high concentration and low temperature. The idea is that, as the comets circle the sun you have long periods of frozen dormancy and shorter periods of 'goldilocks' activity. This could allow for an extended period of evolution before hitting Earth and seeding the oceans with life, or advanced precursors of life, which could have seeded the deep ocean vents. I really like this two stage solution, because it has the same basic processes repeatedly occurring with rather a large range of variations. Twice.

While this is still pretty fanciful at this stage, it's still has more parsimony than proposing life is common in the cosmos.

 

[beero1000]

Just read this. While it's quite convincing evidence that life developed off world, I'm unsure that the conclusion of the paper, that life is common across the universe, is warranted.

https://www.sciencedaily.com/releases/2017/12/171218154925.htm

A theory that has been gaining credence over the last few years involves low temperature development of the prebiotic basis for life, even life, in comets, where the freezing action effectively reduces the water in the equation and drives surprisingly fast processes at high concentration and low temperature. The idea is that, as the comets circle the sun you have long periods of frozen dormancy and shorter periods of 'goldilocks' activity. This could allow for an extended period of evolution before hitting Earth and seeding the oceans with life, or advanced precursors of life, which could have seeded the deep ocean vents. I really like this two stage solution, because it has the same basic processes repeatedly occurring with rather a large range of variations. Twice.

While this is still pretty fanciful at this stage, it's still has more parsimony than proposing life is common in the cosmos.

I don't think that link says anything about life on Earth arriving from elsewhere. Did I miss something?

 

[fast]

A theory that has been gaining credence over the last few years involves ...

That sends mixed signals.

 

[Subsymbolic]

Just read this. While it's quite convincing evidence that life developed off world, I'm unsure that the conclusion of the paper, that life is common across the universe, is warranted.

https://www.sciencedaily.com/releases/2017/12/171218154925.htm

A theory that has been gaining credence over the last few years involves low temperature development of the prebiotic basis for life, even life, in comets, where the freezing action effectively reduces the water in the equation and drives surprisingly fast processes at high concentration and low temperature. The idea is that, as the comets circle the sun you have long periods of frozen dormancy and shorter periods of 'goldilocks' activity. This could allow for an extended period of evolution before hitting Earth and seeding the oceans with life, or advanced precursors of life, which could have seeded the deep ocean vents. I really like this two stage solution, because it has the same basic processes repeatedly occurring with rather a large range of variations. Twice.

While this is still pretty fanciful at this stage, it's still has more parsimony than proposing life is common in the cosmos.

I don't think that link says anything about life on Earth arriving from elsewhere. Did I miss something?

You know what, I read this:

provides strong evidence to support an increasingly widespread understanding that life in the universe is common.

and took it as being an argument that life couldn't have evolved that rapidly on earth, suggesting that life, or some crucial precursors arrived from elsewhere. However, You are quite right, It makes more sense if it's arguing that the speed of evolution suggests it isn't so difficult for life to get out of the blocks.

Still, an interesting bit of data, even if I read the argument that followed from it in a way the authors didn't intend. Good catch!

 

[beero1000]

You know what, I read this:

provides strong evidence to support an increasingly widespread understanding that life in the universe is common.

and took it as being an argument that life couldn't have evolved that rapidly on earth, suggesting that life, or some crucial precursors arrived from elsewhere. However, You are quite right, It makes more sense if it's arguing that the speed of evolution suggests it isn't so difficult for life to get out of the blocks.

Still, an interesting bit of data, even if I read the argument that followed from it in a way the authors didn't intend. Good catch!

It's all good

It's definitely still a really interesting result, showing that relatively complex life arose much more quickly than expected. Cool stuff.

 

[Subsymbolic]

A theory that has been gaining credence over the last few years involves ...

That sends mixed signals.

Perhaps it does. I first heard it proposed at the last UCL origin of life symposium and since then I have heard that argument and arguments like it, more often these days.

If I remember rightly, it was pimped by this lass

New paper suggests life arrived from elsewhere (rather a long time ago)!

and Matt Powner. Obviously the results from Rosetta supported it and it's just an idea which while far from the only one, does seem to be getting more popular. More to the point Matt Powner's recent work on RNA synthesis removes what was seen as being a stumbling block.

I cheerfully admit I'm way outside of my field, but It's something I've been following more as a hobby for a decade or so. If there's any expertise here, I'll be delighted.

 

[Treedbear]

...
I cheerfully admit I'm way outside of my field, but It's something I've been following more as a hobby for a decade or so. If there's any expertise here, I'll be delighted.

Likewise, but it might help to explain the weirdness of the Cambrian explosion.


And coincidently:

The Massive Australian Precambrian/Cambrian Impact Structure also known as MAPCIS is a proposed impact structure based upon arguments presented by Daniel P. Connelly at Geological Society of America meetings. Its center is located approximately equidistant between Uluru (Ayers Rock) and Mount Conner in Australia's Northern Territory. The structure is approximately 600 km (370 mi) in diameter. However, a hypothetical outermost ring 2,000 kilometres (1,200 mi) in diameter is claimed to be the result of undefined far field stresses. Connelly argues that the age of this hypothetical impact is approximately 545 mya which puts it just before the Cambrian explosion (542 mya) of the current Phanerozoic eon (541 mya). If confirmed as an impact structure, it would be the largest on earth.

Although:

... this proposed impact structure is highly speculative and based upon numerous unfounded interpretations,

 

[Subsymbolic]

I don’t have the time any more, but back in the day I’d have built a RC aircraft out of something cool like that and taken great pleasure in flying it around.

 

[skepticalbip]

I don’t have the time any more, but back in the day I’d have built a RC aircraft out of something cool like that and taken great pleasure in flying it around.

Was this one of yours?

 

[lpetrich]

Just read this. While it's quite convincing evidence that life developed off world, I'm unsure that the conclusion of the paper, that life is common across the universe, is warranted.

https://www.sciencedaily.com/releases/2017/12/171218154925.htm

Titled link: Ancient fossil microorganisms indicate that life in the universe is common: Scientists analyze specimens from 3.465 billion years ago -- ScienceDaily -- that's something mentioned in another thread.

A theory that has been gaining credence over the last few years involves low temperature development of the prebiotic basis for life, even life, in comets, where the freezing action effectively reduces the water in the equation and drives surprisingly fast processes at high concentration and low temperature. The idea is that, as the comets circle the sun you have long periods of frozen dormancy and shorter periods of 'goldilocks' activity. This could allow for an extended period of evolution before hitting Earth and seeding the oceans with life, or advanced precursors of life, which could have seeded the deep ocean vents. I really like this two stage solution, because it has the same basic processes repeatedly occurring with rather a large range of variations. Twice.

While this is still pretty fanciful at this stage, it's still has more parsimony than proposing life is common in the cosmos.

That strikes me as an unwarranted inference, because all that can happen in Earth icy conditions.

 

[lpetrich]

I'd already posted some details in "Revisiting the Drake Equation", so I'll repost them here, where those details are also relevant.

Titled link: Odds alien life exists boosted by oldest fossils on Earth - CNET

The surface of planet Earth 3.5 billion years ago was probably quite unpleasant, to put it mildly. There were frequent volcanic eruptions, almost no oxygen and higher chances than today of getting bombarded by large asteroids. Yet somehow a diverse group of life forms was already alive and kicking here, despite such seemingly inhospitable conditions, leading some scientists to presume that the same thing almost surely has happened on other planets as well.

SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions
Of the five species that the authors studied, two were primitive photosynthesizers, one was a methanogen, and two were methane consumers.

So the Eubacteria - Archaea split had happened before 3.5 billion years ago. Chlorophyll photosynthesizers are all in Eubacteria, and methanogens all in Archaea.

Those "inhospitable conditions" are similar to some Earth environments that are known to be inhabited by populations of organisms. Like anaerobic ones, ones without O2. So that's a bit of careless and overdramatic journalism.

 

[lpetrich]

Both  Methanogenesis, as it's called, and photosynthesis have had some evolution behind them.

Methanogenesis is essentially the first part of  Wood–Ljungdahl pathway for fixing carbon into acetic acid, the vinegar acid. That part takes carbon and hydrogen from the environment and makes methyl groups. While W-L then adds more CO2 and H2 to make acetic acid, methanogens add more H2, making methane. Methanogens also have some distinct enzyme cofactors involved in the process, suggesting some evolution behind the process. One of them, methanopterin, is a modification of folic acid, used in W-L.

Photosynthesis uses chlorophyll, and chlorophyll antenna complexes were added on top of existing electron-transfer energy metabolism. The early evolution of photosynthesis is rather complicated and murky, but the first photosynthesizer likely used only one kind of antenna complex. Cyanobacteria and their chloroplast descendants use two kinds, and the ancestral cyanobacterium likely acquired one of them by lateral gene transfer.