Abiogenesis, origin of life still happening today?

[Jens]

Then, if they all "looked alike", they could combine and evolve from there.. and what now may appear to be a single common ancestor could really be multiple common ancestors.

 

The famous Carl Woese (see the corresponding wikipedia page) has a similar argumentation. He thinks that every life is looking alike because it had to evolve into one single precise genetic code (even if started differently from mutliple unprecise codes).

I personally do not follow this argumentation, but I can point you to the corresponding publications and also some counter publication, if you are interested. (or see the reference list on the wiki page).

 

{Note that "genetic code" in science (and not in some popular publications, where it stands for the DNA itself) means the exact translation of the RNA triplets to the corresponding amino acid.}

[Jens]

The reference for Carls Woese theory of the reasons for a unique genetic code is here:

Collective evolution and the genetic code

(Thanks to Carl Woese publishing in PNAS everybody can read publicly funded research results without paying 30$ for every article )

My personal abstract on this (but if you are really interested, read it, because I am not convinced):

 

It is impossible that the genetic code (i.e. the translation of base sequences into amino acid sequence) started with the same precision as it has today. Neither the early form of ribosomes nor the early form of aminoacyl transferases could have the perfection they have today. (aminoacyl transferases are typically double enzymes with a charging and a proofreading catalysis function, to reduce errors to a minimum. So current aminoacyl transferases make less errors than even theoretically possible with one active catalytic center). So there must be some evolution towards a more precise translation. Assuming that horizontal gene transfer played an important role in early evolution, this means that a collective evolution should point into one unique genetic code, even if started from multiple slightly different but unprecise genetic codes. The biggest gene pool gets more and more innovations than the smaller gene pools using a really incompatible genetic code. This is why only one genetic code will survive. Once the organisms have reached a certain level of complexity (the "Darwinian Threshold" introduced by Woese) it was not advantagous to participate in this massive horizontal gene transfer, because all the genes have reached a high level of perfect interaction. This is the point the vertical descendance started and the 3 domains "Bacteria", "Archaea", "Eucarya" branched out of this pool.

 

Note: In case you do not know: Carl Woese is the one who found out that Archaea are something completly else than Bacteria:

Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya

 

To get a complete picture you should also read:

Horizontal gene transfer: A critical view

 

My personal opionion is much more on the side of the last article. However, make up your mind yourself.

Edited November 25, 2012 by Jens

[LogicGates]

Jens, wow thank you for the above replies, which have opened up whole new lines of knowledge for me. Not being a biologist, and having read mostly popular materials on this subject, I did not even know that Carl Woese existed; and now I learn that this famous and acclaimed person gave detailed arguments to support what I only fancied intuitively. This makes me wonder even more than before, why Dawkins stated the theory of a "common ancestor of all life on earth" as if it were a foregone conclusion, and that the probability of life arising spontaneously was assumed to be so incredibly small - and why everyone (at least in the popular works that I've read) agrees with him. All these links you've provided are going to keep me busy for a while. Thanks again!

[Jens]

You are welcome.

 

If you are really interested, you should of course also read about the "mainstream" opinion of abiogenesis:

So I recommend to read some of the articles of RNA worlds.

 

There is also an "outsider" (Wächtershäuser) who is trying to provide real details about why life is inevitable (from his point of view):

Life in a Ligand sphere. and Life as we don't know it.

 

 

I am currently very busy. But before the end of the year I will post my complete thoughts about abiogenesis in this forum.

[Vladimir Mat]

Vladimir Matveev. The great basic question of science: Membrane compartment or non-membrane phase compartment is a physical basis for origin of life?

Oral presentation at The 2nd All-Russian Conference on Astrobiology. Moscow, Pushchino, 5-9 June 2016.

Video in English:

Presentation slides in English as pdf:

http://www.bioparadigma.spb.ru/conf/Matveev-2016-The.great.basic.question.of.science_Eng_Slides.pdf

Comments for slides in English:

http://www.bioparadigma.spb.ru/conf/Matveev-2016-The.great.basic.question.of.science_Comments_Eng.pdf

[seriously disabled]

In "Through the wormhole season 1 episode 5 - how did we get here?" Morgan Freeman says that the origin of life will always be a mystery and that this question might never get an answer.

[Strange]

While that is (trivially) true it is not very helpful. It is true of just about any question.

 

However, there is still a lot of really interesting work being done that might lead to plausible answers. For example, just recently:

http://www.nature.com/articles/nmicrobiol2016116

 

 

The 355 phylogenies identify clostridia and methanogens, whose modern lifestyles resemble that of LUCA, as basal among their respective domains. LUCA inhabited a geochemically active environment rich in H2, CO2 and iron. The data support the theory of an autotrophic origin of life involving the Wood–Ljungdahl pathway in a hydrothermal setting.

[sethoflagos]

I found this paper quite fascinating.

 

http://www.nature.com/articles/srep00263

 

Could competition for very rare and limited sources of biologically available molybdenum have put a serious restriction on multiple contenders for the first life, as this paper seems to infer?

[CharonY]

I am not sure whether there was a lot of competition in the early stages. It really depends what is more limiting, i.e. how many theoretical vial options there were to begin with. Obviously, the study can only address precisely one form.

[seriously disabled]

Scientists often take chemical evolution for granted but it's possible that life just isn't chemical in nature.

 

Personally I don't think that the origin of life will ever be figured out by scientists. I'm just not convinced.

 

There are things that science will just never be able to explain, not even in a million years from now.

Edited August 25, 2016 by seriously disabled

[Ophiolite]

Scientists often take chemical evolution for granted

I thought they took it for an observed fact. i.e. we see chemicals proceeding from reactants to products.

 

 

it's possible that life just isn't chemical in nature.

Then what is it?

 

 

Personally I don't think that the origin of life will ever be figured out by scientists. I'm just not convinced.

Personal incredulity is a weak position from which to argue.

 

 

There are things that science will just never be able to explain, not even in a million years from now.

Foremost among these may be "Why do some people say truly dumb things?"

[Cynic]

Simple minded sort that I am, I always just assumed that if something like that happened, it would be a tasty snack for something else...which would not have been the case way back when.

 

It does raise an interesting question though for me, if there was some sort of biogenesis still happening, it seems there would be a decent chance of it having different handedness, or is there something favoring the handedness of life as it is now?