New findings challenge assumptions about origins of life

Sep 13, 2013

Before there was life on Earth, there were molecules. A primordial soup. At some point a few specialized molecules began replicating. This self-replication, scientists agree, kick-started a biochemical process that would lead to the first organisms. But exactly how that happened—how those molecules began replicating—has been one of science's enduring mysteries.

Now, research from UNC School of Medicine biochemist Charles Carter, PhD, appearing in the September 13 issue of the Journal of Biological Chemistry, offers an intriguing new view on how life began. Carter's work is based on lab experiments during which his team recreated ancient protein enzymes that likely played a vital role in helping create life on Earth. Carter's finding flies in the face of the widely-held theory that Ribonucleic Acid (RNA) self-replicated without the aid of simple proteins and eventually led to life as we know it.

In the early 1980s, researchers found that ribozymes—RNA enzymes—act as catalysts. It was evidence that RNA can be both the blueprints and the that put those blueprints into action. This finding led to the "RNA World" hypothesis, which posits that RNA alone triggered the rise of life from a sea of molecules.

But for the hypothesis to be correct, ancient RNA catalysts would have had to copy multiple sets of RNA blueprints nearly as accurately as do modern-day enzymes. That's a hard sell; scientists calculate that it would take much longer than the for randomly generated RNA molecules to evolve sufficiently to achieve the modern level of sophistication. Given Earth's age of 4.5 billion years, living systems run entirely by RNA could not have reproduced and evolved either fast or accurately enough to give rise to the vast on Earth today.

"The RNA world hypothesis is extremely unlikely," said Carter. "It would take forever."

Moreover, there's no proof that such ribozymes even existed billions of years ago. To buttress the RNA World hypothesis, scientists use 21st century technology to create ribozymes that serve as catalysts. "But most of those synthetic ribozymes," Carter said, "bear little resemblance to anything anyone has ever isolated from a living system."

Carter, who has been an expert in ancient biochemistry for four decades, took a different approach. His experiments are deeply embedded in consensus biology.

Our genetic code is translated by two super-families of modern-day enzymes. Carter's research team created and superimposed digital three-dimensional versions of the two super-families to see how their structures aligned. Carter found that all the enzymes have virtually identical cores that can be extracted to produce "molecular fossils" he calls Urzymes—Ur meaning earliest or original. The other parts, he said, are variations that were introduced later, as evolution unfolded.

These two Urzymes are as close as scientists have gotten to the actual ancient enzymes that would have populated the Earth billions of years ago.

"Once we identified the core part of the enzyme, we cloned it and expressed it," Carter said. "Then we wanted to see if we could stabilize it and determine if it had any biochemical activity." They could and it did.

Both Urzymes are very good at accelerating the two reactions necessary to translate the genetic code.

"Our results suggest that there were very active very early in the generation of life, before there were organisms," Carter said. "And those enzymes were very much like the Urzymes we've made."

The finding also suggests that Urzymes evolved from even simpler ancestors—tiny proteins called peptides. And over time those peptides co-evolved with RNA to give rise to more complex life forms.

In this "Peptide-RNA World" scenario, RNA would have contained the instructions for life while peptides would have accelerated key chemical reactions to carry out those instructions.

"To think that these two Urzymes might have launched protein synthesis before there was life on Earth is totally electrifying," Carter said. "I can't imagine a much more exciting result to be working on, if one is interested in the origin of life."

The study leaves open the question of exactly how those primitive systems managed to replicate themselves—something neither the RNA World hypothesis nor the Peptide-RNA World theory can yet explain. Carter, though, is extending his research to include polymerases—enzymes that actually assemble the RNA molecule. Finding an Urzyme that serves that purpose would help answer that question.

The study's co-authors include Li Li of UNC and Christopher Francklyn of the University of Vermont, Burlington.

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phymat
3 / 5 (5) Sep 13, 2013
An interesting approach for describing evolution. It also makes the logic more clear.
Anda
3.4 / 5 (5) Sep 13, 2013
Interesting. Another little step to understand the process.
That's how it works, step by step, try and error, refining theories "obama_socks sucks" (you won't understand it anyway).
And phymat, for me evolution and genesis are different things.
one is the evolution of living beings, the other the origin of the first living beings (an evolutionary process, but not the same one)
RealScience
4.5 / 5 (8) Sep 13, 2013
@Anda - agreed - pre-biotic soups and life can both evolve, and they evolve differently.
But the difference is not that great, and there is likely no clear dividing line between pre-biotic and life.

An ecosystem of molecules that mutually catalyzed the formation of similar molecules would not reproduce as a unit because it would only 'seed' (or infect) other regions with relatively random subsets of the molecules in its 'soup', and yet it would start to evolve even without any single molecule serving as a 'genetic' repository for inheritable information, and it would start to spread even with significant variation in every region it spreads to.

Is such an intermediate state life or not (or at what point does one call it life)?
kevin_buckeye_3
2.4 / 5 (14) Sep 13, 2013
@Obama Socks...If you knew anything about science,you would know that RNA enzymes,and proteins,etc...All they need is heat (energy).

Use your brain before you speak next time. Anti-science Nazi.
kevin_buckeye_3
1.5 / 5 (10) Sep 13, 2013
@RealScience....Exactly. I'm considering how there were more than one catalyst. The sun's energy is another catalyst that speeds up chemical reactions.

All it takes is heat and these enzymes all produce life.

weezilla
5 / 5 (5) Sep 13, 2013
*Precisely. In order for those primitive systems to replicate themselves, they would already have had to be alive. Replication in that sense, amounts to procreation. They would have had to be living material in order to replicate or procreate using available molecular material.


Replication doesn't carry the requirement of being alive. The question I'm interested in is, how many different probable initial formulations are there where self-replication and information propagation result.
St_BarthGirl
1.4 / 5 (9) Sep 13, 2013
@ Real Science: I've been thinking recently about the spectrum- about what qualifies as "Alive". I'm a lay person, not a scientist. I believe I've sussed an answer that satisfies me: It's a Life when it can die. It's that Simple. If not being "alive" has an effect on things around it- it's environment, it's confreres, then it has Died~ and thus it had a life.

But even this, tho true, isn't the full truth. Molecules effect everything else they contact- their destruction sets off a chain reaction. So maybe- EVERYTHING is Alive? That old conundrum about fire may not be so far off. If everything is interdependent- and as I grow up, I see more and more that it is, then who's to say there isn't a means of looking at just about anything inanimate and saying it doesn't feed, or reproduce- etc... and a molecule depends on atoms to live, to grow. To die. Self-similar systems from the most quantum levels to the most macro- it's astonishing how analogous natural processes are...
RealScience
3 / 5 (2) Sep 13, 2013
@weezilla - On earth most likely thousands of chemical ecosystems existed as molecules that catalyzed each other's replication drifted from their ecosystem to other places with similar chemical resources. If these places were alkaline hydrothermal vents, then each such ecosystem would have billions of tiny prokaryote-cell-sized pores concentrating the more complex chemicals.

Whichever ecosystems reproduced best spread most widely, and evolution was rapid because exchange between pores in would have been frequent and exchange between ecosystems not uncommon. It appears that two proto-genetic-codes merged to form our current four-letter code, and that the first ecosystem to master this out-competed all other ecosystems.

It also appears that two replicants of this ecosystem independently developed cell membranes that let cell roam free of the pores, allowing pools of such ecosystems to travel together, and thus we have two types of cell membranes on prokaryotes.

It also appea

RealScience
3.7 / 5 (3) Sep 13, 2013
@St BarthGirl:
That transfers the problem of life to the problem of defining dying.
Does a crystal die if I smash it?
Does a fire die if its last ember goes out?
Does a language die if its last speaker dies?

But then scientists don't have a great definition for life either!
(And those that do have definitions don't seem to agree with each other.)

Personally I think of life as 'that which has evolved to evolve'. That encompasses the local lowering of entropy through information accumulation, and distinguishes life from things like fire.

hrfJC
3.5 / 5 (2) Sep 13, 2013
The late Leslie Orgel examined several hypotheses regarding molecular evolution from inorganic species and published his findings in 2008 in PLoS under the title The Implausibility of Molecular Evolution ending with the conclusion that they are based on speculative if pigs could fly chemistries. Indeed simple inspection of the classical chart of metabolic pathways, known to all biochemistry majors, shows that forming a living cell would require instantaneous AND simultaneous formation of hundreds of different substrates and their specific enzymes to generate a functional living cell, a statistically impossible event. Stepwise evolution over billion of years must therefore excluded in molecular evolution but may have occurred at later evolutionary stages.
barakn
3.9 / 5 (7) Sep 13, 2013
This is one of the most interesting threads I've seen in a while. Not because of the quality of the posts, mostly because someone decided to create an account with the username of moderator and discovered a bug that allowed them to sink individual post ratings down to negative 1. Use your powers while you can, moderator, you won't have them long. And HeinousDov has gone past the 1000 char post limit several times.
RealScience
5 / 5 (3) Sep 13, 2013
RealScience

Pre-biotic soups are only the pre-life materials. It contains the ingredients to be distributed, rearranged and ordered into a viable life form that germinates and ultimately evolves. But first, there has to be life that can reproduce
...but it goes nowhere unless the catalyst that can give its existence "life" presents itself.... A compound of CHNOPS cannot suddenly come alive without a powerful catalyst.


No, a soup of molecules that mutually catalyze replication of those molecules has no one key catalyst that separates reproducing from not reproducing.

It can produce more soup, although initially not with the same proportion of ingredients as the existing soup. It doesn't suddenly come alive, it evolves to reproduce more and more accurately (until that limits its evolution and it evolves to mutate at useful rates). At some point we call it life, but there really is no sharp boundary.
RealScience
5 / 5 (5) Sep 14, 2013
@barakn - I think that it is an actual moderator because "moderator's" -1 overrides any other rankings to produce an average of -1, so moderator would have had to hack the averaging code, too, which seems unlike.

But I also was wondering how HDov got past the 1000-char limit. Of course he's posting from the 22nd century, and so has had many decades to figure it out ;-)
Captain Stumpy
2.1 / 5 (11) Sep 14, 2013
But I also was wondering how HDov got past the 1000-char limit. Of course he's posting from the 22nd century, and so has had many decades to figure it out ;-)


I was wondering too... but this is not the first time I've seen this happen... in a few other threads I have seen other posters do this. it is almost like a spam ad, really.
adave
1 / 5 (2) Sep 14, 2013
A pre biotic missing link mineral has not been discovered (some proposed mineral formations have been close). It's effect would be 2D. New life should be found all of the time. The only new life other than the first life might have been eukaryotic two billion years ago. Life is a 3D structure that can arise from a liquid environment. Life also contains a program to cause it to be a state machine. It runs on low entropy energy. Our entire planet is mineral like except for a thin film of life. When life is broken it becomes like a mineral. Remove water from some seeds and spores and they will be lifeless until rehydrated. A computer is a state machine and more like a mineral. The only reason it is different from inert silicon is that it has a program and runs on low entrophy energy. It also does not occur as a mineral. Life as a state machine requires more degrees of freedom than exists in a mineral like universe. Life can only come from pre-existing life.
barakn
5 / 5 (4) Sep 14, 2013
@RealScience - having been a victim of phys.org's actual admins myself, I can assure you they don't bother downrating posts. They simply remove the post and send a PM stating why they've done it. Plus there's the fact that the moderator account was created today at 1 AM, whereas phys.org and its predecessor physorg.com have been allowing comments for 6 years. The site admins generally have to have their arms twisted before they will remove posts or users, whereas 'moderator' seems to have a personal vendetta against obama_socks. This is a classic case of adoption of a reserved word as a username resulting in unintentional privilege escalation.
Gmr
1 / 5 (2) Sep 14, 2013

Replication doesn't carry the requirement of being alive. The question I'm interested in is, how many different probable initial formulations are there where self-replication and information propagation result.


Look for high degrees of freedom (widely variable setups) without one obvious point of stability. So, probably carbon based, but beyond that we can't say...
Gmr
2.3 / 5 (3) Sep 14, 2013
@barakn - I think that it is an actual moderator because "moderator's" -1 overrides any other rankings to produce an average of -1, so moderator would have had to hack the averaging code, too, which seems unlike.

But I also was wondering how HDov got past the 1000-char limit. Of course he's posting from the 22nd century, and so has had many decades to figure it out ;-)


Both questions come down to where your validation lies - if it's server side, it's quite a trick - but I suspect the char limit is client side, so right-click-paste plus click the button, and you're past the limit, or alternately submit directly to the URL specified for the form.

I suspect the same applies to the "-1" and the system doesn't know how to average a -1 in with the rest of the numbers. Neat trick.
A_Paradox
3 / 5 (3) Sep 14, 2013
Replication doesn't carry the requirement of being alive. The question I'm interested in is, how many different probable initial formulations are there where self-replication and information propagation result.


weezilla, I think you are right. What is at issue is the number and kinds of _structures_ that can exist which, while they exist, influence the rest of their world such that one out come of their existence [even if they disappear] is that a similar thing comes together again with a higher probability than would be the case if the first instance had not occurred.
Earth has various cyclical processes which have been occurring ever since the ocean stopped boiling. Some are 'physical' like alternation of night and day, evaporation of water and its falling as rain which falls on land to dissolve elements from the rocks, and another flow - of ocean water into the crust near spreading centres and its convective upwelling with many dissolved elements.
.. to continue
A_Paradox
1 / 5 (2) Sep 14, 2013
continued ...
Those cycles of water through mineral laden rocks and back into the ocean again form the basis of some chemical cycles, for example the CO2 to carbonic acid to calcium carbonate pathway. I'm no chemist so I can't list them but I have read of several in Scientific American articles over the years.

The evolution of processes that produced organic catalysts was obviously a key stage in the changes that resulted in what we now call Life on Earth. The simplest logic says they did evolve, and that was because they could! The ocean is now different from its original chemical composition however as much as anything _because _ certain strange attractor type situational repetitions became ecological niches for certain 'lucky' associations of replicators.

People like Charles Carter PhD are going to keep on finding out ever more details of how the whole process evolved. It is just 413 years since they murdered Giordano Bruno; still early days yet in the great adventure!
alfie_null
5 / 5 (1) Sep 14, 2013
Both questions come down to where your validation lies - if it's server side, it's quite a trick - but I suspect the char limit is client side, so right-click-paste plus click the button, and you're past the limit, or alternately submit directly to the URL specified for the form.

I suspect the same applies to the "-1" and the system doesn't know how to average a -1 in with the rest of the numbers. Neat trick.

The allure of javascript. For web site authors, like making a deal with the devil.

These participants who are have been rated so low - their averages are now permanently under water. A mess to clean up.
Anonym
1.6 / 5 (10) Sep 14, 2013
"This self-replication, scientists agree, kick-started a biochemical process that would lead to the first organisms." --- LOL. The phrase "scientists agree" is the tip-off that there's a whopper coming.

Let's recast this lede:

"Before there was cars on Earth, there were molecules. A primordial soup. At some point a few specialized molecules began replicating....but billions of years would pass before the initial coalescence of those specialized molecules would lead to the crown of creation, the carburetor."

Even knowing the twists and turns of how RNA came to make organic tissue won't solve the
problem of the carburetor. The question for science is why did the carburetor require organic Life at all, and will future carburetors rely on cumbersome and unpredictable organic Life to evolve?

beleg
1.8 / 5 (8) Sep 14, 2013
That encompasses the local lowering of entropy through information accumulation, and distinguishes life from things like fire. - Real

An intriguing attempt.
Matter condenses. And passes your stipulations.
Life is information transfer (not information transmission - a distinction one is forced to make.)
This transfer alters at a point where humans label this point 'death'.
Torbjorn_Larsson_OM
1 / 5 (1) Sep 14, 2013
Vital research. However the beginning is a sensationalist press release that describes tearing down a strawman.

The "soup" and the more constrained "pure RNA world" haven't been popular pathways lately. Astrobiologists have been forced to consider these "dirty RNA world" pathways by reasons chemical (say, need redox potentials as in later cells) and phylogenetic (say, metabolism has evolved from geochemistry).

In fact, the dirty RNA world seems to be the consensus:

"The 1986 paper by Wally Gilbert describes a pure RNA World, where you have RNA running all of metabolism and information transduction. It's all RNA, all the time, and nothing else. I don't think many people accept that as reasonable anymore. In that sense the original RNA World model is dead.

[tbctd]
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
[ctd]

But what has happened is that people have adapted and modified the model. There are now dirty RNA World models in which RNA collaborates with other molecules. Most people now are assuming that amino acids, peptides and a variety of other molecules were involved along with RNA."

[ http://www.scoop....dead.htm ]

Also, one has to wonder about the creationist model Carter uses to 'reject' a pure RNA world. We do know that RNA accuracy is enough to crystallize replicating strands by thermodynamical free energy forcing, and that evolution would proceed from there.

Moreover, it has been recently shown that early RNA was capable of the same electron transfer as proteins are under Hadean and early Archean conditions of no oxygen and dissolved iron(II). In fact, the ribosome preserved RNA core is the best such catalyst found, it kicks in before the others at lower concentrations.

[tbctd]
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
[ctd]

That is of course another win for the dirty RNA world, having the translation machinery core been co-opted from earlier catalyst use.

["RNA with iron(II) as a cofactor catalyses electron transfer", Hsiao, Nature Biochemistry 2013]
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
First the trolling:

Creationist trolling is hilarious. And also counterproductive, it makes deconverts from religion, see Dawkins's Convert's Corner.
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
Then the science:

@Anda: "different things." Good point.

I agree that it used to be different things, chemical evolution well separated from biological evolution. But last year Lane & Martin showed how early cell metabolisms are phylogenetically related with common biochemistry (of alkaline hydrothermal vents). AFAIK no peer criticism has removed that phylogeny.

So today we have the "no clear dividing line" that RealScience describes.

Granted, many of the evolutionary mechanisms that apply to explicit hereditary systems (genes) does not apply. But the essential process of "variation and selection" does.

And what is seen to be the initial state of protocell populations, selective sweeps encompassing cells with rampant sharing of traits (no clear lineages yet), is essentially the same selective sweeps that RealScience describes as what would have happened before protocell chemistry.
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
@hrfJC: "Orgel". Lane and Martin showed that Orgel was wrong.

"biochemistry majors".

No, simple inspection of cells by _biologists_ shows that they must have evolved from simpler systems. Indeed, that it has been the case is what L&M's observation means.

Even if it hadn't been a tested observation, your alternative is creationist and not applicable science.

@kevin_buckeye: "All they need is heat (energy)." Agreed, in the sense that this builds the required redox sources. (The "soup" heat chemistry is seen as less likely today. Orgel had a point there.)

A technical nitpick is that an energy source is not a catalyst. A catalyst is what lowers the energy barrier for the reaction so less energy from the sources is needed. It is a "negative source" in some twisted math sense. =D
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
@St_BartGirl: Well, I can't add much to what RS already have said.

FWIW my preliminary definition of life has long been the process of life itself, biological evolution. Akin to how gravity or EM is defined.

Its vehicles in modern times is selfish genes, but it goes (arguably, of course) back to selfish geochemistries. Today's vents are "dead", the changed environment has made them go extinct as selfish geochemistries. But early on they were likely the first vehicles, the first biochemically active populations that can be considered having been "alive". (Evolving and later replicating metabolism, likely spreading reproduction of chemistries to new vents.)
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
@weezilla: "how many different probable initial formulations". All of them. =D

Really, as far as RNA goes. In chemical models with experimentally measured parameters a random RNA strand "gas" that comes out of activated nucleotides (out of vent chemistry) crystallizes a replicator strand from thermodynamic free energy forcing. ["Thermodynamic Basis for the Emergence of Genomes during Prebiotic Evolution", Woo et al, PLOS Comp Biol 2012]

Life needs only hit on RNA to evolve the selfish genes we see today.

Since its component sugar and nucleotides are those that best stabilize, and what ribose is best stabilized by, protocell membrane lipids, there is a clear evolutionary route to RNA. ["Nucleobases binds to and stabilize aggregates of a prebiotic amphiphile, providing a viable mechanism for the emergence of protocells", Black et al, PNAS 2013]

[tbctd]
Torbjorn_Larsson_OM
2.3 / 5 (3) Sep 14, 2013
[ctd]

The dirty RNA world evolutionary pathway under the observed phylogeny could be: geochemistry = alkaline hydrothermal vent redox chemistry -> most productive FeS and peptide assisted metabolism within inorganic membranes -> more protocells by RNA-stabilized organic membranes -> more productive protocells by co-option of RNA as catalyst -> more cells by co-option of RNA as explicit hereditary mechanism = the universal common ancestry cell community.

This last is the stage Carter research. There are also many simple pathways from RNA catalyst replication to protein translation replication, since RNA can assist itself with strand separation et cetera. The simplest, which checks with phylogenies, made random proteins and a trinary proto-code just to replicate RNA unidirectionally by the smallest possible brownian ratchet.

At all stages vent chemistry could infect new vents by passive drift of inert components.
RealScience
3 / 5 (2) Sep 14, 2013
having been a victim of phys.org's actual admins myself, I can assure you they don't bother downrating posts. They simply remove the post and send a PM stating why they've done it. Plus there's the fact that the moderator account was created today at 1 AM, whereas phys.org and its predecessor physorg.com have been allowing comments for 6 years. The site admins generally have to have their arms twisted before they will remove posts or users, whereas 'moderator' seems to have a personal vendetta against obama_socks. This is a classic case of adoption of a reserved word as a username resulting in unintentional privilege escalation.


@barakn - thanks - after reading your post I believe that your explanation is better than mine.
RealScience
1 / 5 (2) Sep 14, 2013
Matter condenses. And passes your stipulations.

@beleg - matter condensing has not evolved to evolve.
Even fire has not evolved to evolve.
(However the suggested short definition is incomplete - even a dead person evolved to evolve - they are just no longer capable of contributing to the process.)

There are interesting cases at the boundaries: Some languages have evolved to evolve (English in particular has evolved to avidly absorbs words from other languages rather than rejecting them, and hence evolves faster than most languages). Are languages alive?
I think that to a non-negligible extent a language can be considered alive.

And if you extract DNA from a cell, is it the DNA that is alive or the rest of the cell that is alive? At least one must be because you can add the DNA back to such a cell and it starts reproducing and metabolizing again (as Ventner has shown, the cell doesn't even have to be the same species).
Torbjorn_Larsson_OM
1 / 5 (2) Sep 14, 2013
Darwin, my astrobiology interest really spam such threads!

But after loooking for the paper (paywalled) I found a short exposé. [ http://www.jbc.or...full.pdf ] Seems Carter isn't arguing from a creationist viewpoint, but from Koonin's "Many World" scenario of early chemistries.

That in turn derives from a failure to "grok" selection bias in cosmology. Selection bias ("weak anthropic selection") on environments means you see the environments that are most likely to have life. It often comes out as a gaussian distribution centered between non-life excluded environments.

Meaning there is a higher probability of such environments. Or you have to finetune them to have just one.

Koonin misunderstood and it results in the finetuned random event that happens if you have little or no chemical evolution at all. (As they argue must happen for pure ribozymes.) In other words, the "freak accident" of Monod mitigated by many planets.

Else, the abstract seems promising!
Torbjorn_Larsson_OM
1 / 5 (2) Sep 14, 2013
"is it the DNA that is alive or the rest of the cell".

Both are inherited, but the cell machinery is directly inherited (under modification) from the "ur-cell". DNA codes for replacement and repair et cetera, but needs a machinery to work. (Outside of Ventner's manipulations.)

Dawkins threw the machinery away (:-/) on short notice as I understand it. His selfish gene concept shows how today the genes are the vehicles of evolution.
RealScience
3 / 5 (2) Sep 14, 2013
@TL - We have no example of a cell 'booting' since the 'ur-cell', and it is still an RNA-lead world, so I agree - the cell-DNA is alive.

But viruses show that genomes are alive, too.
Although many say that they are not alive, viruses, too, have evolved to evolve, and they metabolize and reproduce. And since we need to use vitamins, minerals, carbohydrates, lipids, and proteins produced by other life forms to survive and reproduce, we should not hold it against viruses that they need to use ribosomes produced by other life forms (Asimov said it well decades ago - is someone who cuts wood as a profession not a wood-cutter when he doesn't have an ax with him?).

Nothing replicates without its relatively special environment - genes need a host of RNA and proteins in a bath of water and ATP, cells need nutrients, languages need speakers, etc. And viruses need cells (although some are more complex than simple cells).

Thus I see life as a matter of degree, rather a binary state.
Torbjorn_Larsson_OM
1 / 5 (1) Sep 15, 2013
Oh, I agree, viruses are alive. They simply rely on a cellular environment when they are in the mature state instead of the usual spore state. Viruses have been described as molecular organisms instead of cellular organisms.

They don't seem to form a monophyletic clade of coat proteins, as much as a many times settled niche.

But these proteins are related to pore complexes which all cells have. So a major pathway to viruses may be parasitic simplification from cells. The Mega- and Panda viral clade of huge dsDNA viruses seems to be such a clade that branched before the 3 other domains according to the Panda virus paper [tree in the supplement, if you need a ref] and protein fold papers. We can then expect some of the RNA viruses branched similarly before the DNA UCA evolved.
Torbjorn_Larsson_OM
1 / 5 (1) Sep 15, 2013
I can relate to the idea of "evolve to evolve" as a) people study evolvability, and b) there is a clear correlation over 7-8 order of magnitudes between mutation rate and genome size. The latter is likely a result of a balance between cost of mutational load and cost of maintaining or loosing fidelity.

However a) is not fruitful yet AFAIK and b) is just an opening for research. I don't know how we would quantify "evolve to evolve". Maybe the rate-size correlation suggests a test. E.g. "evolve to evolve" predicts evolution is under evolution control.

That in turn _is_ measurable as a correlation, and the result spans everything from uncapsulated viroids to eukaryotes. (Though as would be expected, fussily so in the latter case, as they may have many other ways to regulate evolution rates.) This is testable:

http://jvi.asm.or...ion.html (from http://jvi.asm.or...247.full )

So, yeah.
Torbjorn_Larsson_OM
1 / 5 (1) Sep 15, 2013
If I would compare the two ideas now I would say:

- That "evolve to evolve" can perhaps be quantitatively substantiated and it covers what some, but not all, are prepared to define as "life". So it is good and perhaps conservative enough.

Needs some work though.

- That "selfish biochemistries" can be quantitatively substantiated (phylogenies), generalizes on Dawkins's well understood and accepted "selfish gene" concept so has also some conservative grounding, but is way out there.

Needs a lot of work. =D
Moebius
1.7 / 5 (7) Sep 15, 2013
No theory about how life began will ever be complete without using it to create life. That will be difficult without knowing what the first life was.
beleg
1 / 5 (4) Sep 15, 2013
There many beginnings. Infinite ways or paths of interaction information can take - in fact so many interactions that any description or definition you use to label life or death via physics, chemistry or biology will always provide an interaction not considered beforehand. You will always come up an interaction short until you create life to your satisfaction. Use information to create life.
Call life information. That avoids searching for a beginning...or searching for a first. Right now you are simply exploring the interactions of information to fit your present day bill of biology, chemistry , physics, life and death. Rightly so. You have no other choice.
Neinsense99
1.7 / 5 (6) Sep 16, 2013
But I also was wondering how HDov got past the 1000-char limit. Of course he's posting from the 22nd century, and so has had many decades to figure it out ;-)


I was wondering too... but this is not the first time I've seen this happen... in a few other threads I have seen other posters do this. it is almost like a spam ad, really.

I have seen something similar with one of the earlier Vendicar versions, where a mass of low ratings would lower his average score below 1 but not below zero. 0.2 with 40 votes and that sort of thing. Would it be the same method or something different?