Author Topic: Re: How Life May Have First Emerged On Earth (Abiogenesis Thread)  (Read 1977 times)

Icarus

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Ken Hamm ain't gonna' like this

Recusant

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Re: How Life May Have First Emerged On Earth (Abiogenesis Thread)
« Reply #1 on: October 22, 2015, 07:28:42 AM »
Well, at least we have one post from this thread, so I'll add to it, as a token of my belief that the rest of the posts will be restored by our splendid Grey Adminence.  :asmo:

* * *

Some very interesting evidence has been found which may be an indication that life began considerably earlier than previously thought.

"Life on Earth likely started 4.1 billion years ago, much earlier than scientists thought" | Geology Page

Quote
UCLA geochemists have found evidence that life likely existed on Earth at least 4.1 billion years ago -- 300 million years earlier than previous research suggested. The discovery indicates that life may have begun shortly after the planet formed 4.54 billion years ago.

The research is published today in the online early edition of the journal Proceedings of the National Academy of Sciences.

"Twenty years ago, this would have been heretical; finding evidence of life 3.8 billion years ago was shocking," said Mark Harrison, co-author of the research and a professor of geochemistry at UCLA.

. . .

The researchers, led by Elizabeth Bell -- a postdoctoral scholar in [Mark] Harrison's laboratory -- studied more than 10,000 zircons originally formed from molten rocks, or magmas, from Western Australia. Zircons are heavy, durable minerals related to the synthetic cubic zirconium used for imitation diamonds. They capture and preserve their immediate environment, meaning they can serve as time capsules.

The scientists identified 656 zircons containing dark specks that could be revealing and closely analyzed 79 of them with Raman spectroscopy, a technique that shows the molecular and chemical structure of ancient microorganisms in three dimensions.

Bell and [Patrick] Boehnke, who have pioneered chemical and mineralogical tests to determine the condition of ancient zircons, were searching for carbon, the key component for life.

One of the 79 zircons contained graphite -- pure carbon -- in two locations.

"The first time that the graphite ever got exposed in the last 4.1 billion years is when Beth Ann and Patrick made the measurements this year," Harrison said.

[Continues . . .]

The full paper is available as well. "Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon" | Proceedings of the National Academy of Sciences (PDF)
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Recusant

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« Last Edit: January 05, 2017, 02:29:41 AM by Recusant »
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Recusant

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Re: How Life May Have First Emerged On Earth (Abiogenesis Thread)
« Reply #3 on: April 25, 2016, 11:37:36 PM »
More that Ken Ham and other Creationist science deniers won't like.

"Missing links brewed in primordial puddles?" | ScienceDaily

Quote
The crucibles that bore out early building blocks of life may have been, in many cases, modest puddles.

Now, researchers working with that hypothesis have achieved a significant advancement toward understanding an evolutionary mystery -- how components of RNA and DNA formed from chemicals present on early Earth before life existed.

In surprisingly simple laboratory reactions in water, under everyday conditions, they have produced what could be good candidates for missing links on the pathway to the code of life.

And when those components joined up, the result even looked like RNA.

As the researchers' work progresses, it could reveal that much of the original chemistry that led to life arose not in fiery cataclysms and in scarce quantities, but abundantly and gradually on quiet, rain-swept dirt flats or lakeshore rocks lapped by waves.

[Continues . . .]

The full paper ("Spontaneous formation and base pairing of plausible prebiotic nucleotides in water") is available for free from Nature.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken


Icarus

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Re: How Life May Have First Emerged On Earth (Abiogenesis Thread)
« Reply #4 on: April 26, 2016, 01:09:59 AM »
Thank you the links Rec. Sad to say that our fundie friends will not place much stock in such heady stuff.

Tank

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Re: How Life May Have First Emerged On Earth (Abiogenesis Thread)
« Reply #5 on: April 26, 2016, 06:29:22 AM »
Very interesting.
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Re: How Life May Have First Emerged On Earth (Abiogenesis Thread)
« Reply #6 on: September 22, 2017, 04:36:45 PM »
The pop-science headlines about the paper described below overstate things per usual (as does the linked article itself). Some of the statements of its authors are also unsupportable in the context of their findings. Nonetheless, it does appear to be a breakthrough in learning about a plausible scenario for the beginning of life here on Earth.

"Complex life evolved out of the chance coupling of small molecules" | PhysOrg

Quote
Complex life, as we know it, started completely by chance, with small strands of molecules linking up, which eventually would have given them the ability to replicate themselves.

In this world, billions of years ago, nothing existed that we would recognise today as living. The world contained only lifeless molecules that formed spontaneously through the natural chemical and physical processes on Earth.

However, the moment that small molecules connected and formed larger molecules with the ability to replicate themselves, life started to evolve.

"Life was a chance event, there is no doubt about that," says Dr Pierre Durand from the Evolution of Complexity Laboratory in the Evolutionary Studies Institute at Wits University, who led a project to find out how exactly these molecules linked up with each other. Their results are published today in the journal Royal Society Open Science, in a paper entitled "Molecular trade-offs in RNA ligases affected the modular emergence of complex ribozymes at the origin of life".

Very simple ribonucleic acid (RNA) molecules (compounds similar to Deoxyribonucleic acid(DNA)) can join other RNA molecules to themselves though a chemical reaction called ligation. The random joining together of different pieces or RNA could give rise to a group of molecules able to produce copies of themselves and so kick start the process of life.

While the process that eventually led to the evolution of life took place over a long period of time, and involved a number of steps, Wits PhD student Nisha Dhar and Durand have uncovered how one of these crucial steps may have occurred.

They have demonstrated how small non-living molecules may have given rise to larger molecules that were capable of reproducing themselves. This path to self-replicating molecules was a key event for life to take hold.

"Something needed to happen for these small molecules to interact and form longer, more complex molecules and that happened completely by chance," says Durand.

[Continues . . .]

The conclusions of the paper (available for free here) are less sensationalized and make the actual findings fairly clear:

Quote
Ligases (and related polymerases) have primarily been explored with the aim of evolving a self-replicating enzyme. However, while these self-replicating ribozymes are key components of a replicating RNA world, an explanation is needed for the emergence of such molecules that are much larger in size than those that formed spontaneously in the prebiotic world.

This study reveals how the activity of small ligases could have led to larger, more complex molecules. The ligases exhibited differential functional flexibility and efficiency which correlated with their size and stability. The results indicate that, in the early stages of the RNA world, molecular size could have increased in a modular, stepwise fashion via the reactions of small ligases with a range of oligomers, albeit with a relatively poor efficiency. It supports the computational and theoretical predictions that assembly of larger functional molecules resulted from short RNA ligases. The derived larger and more complex ligases developed specificity and efficiency for the kinds of substrates ligated. This trade-off could have contributed to building molecular complexity and the generation of a pool of functionally specialized molecules, which were necessary for the emergence of a self-sustained replicating system.
"Religion is fundamentally opposed to everything I hold in veneration — courage, clear thinking, honesty, fairness, and above all, love of the truth."
— H. L. Mencken